Efficient oxygen electrocatalysts are the key elements of numerous energy storage and conversion devices, including fuel cells and metal-air batteries. In order to realize their practical applications, highly efficien...Efficient oxygen electrocatalysts are the key elements of numerous energy storage and conversion devices, including fuel cells and metal-air batteries. In order to realize their practical applications, highly efficient and inexpensive non-noble metal-based oxygen electrocatalysts are urgently required. Herein, we report a novel iron-chelated urea-formaldehyde resin hydrogel for the synthesis of Fe-N-C electrocatalysts. This novel hydrogel is prepared using a new instantaneous （20 s） one-step scalable strategy, which theoretically ensures the atomic-level dispersion of Fe ions in the urea-formaldehyde resin, guaranteeing the microstructural homogeneity of the electrocatalyst. Consequentl~ the prepared electrocatalyst exhibits higher catalytic activity and durability in the oxygen reduction （ORR） and evolution （OER） reactions than the commercial Pt/C catalyst. Furthermore, the above catalyst also shows a much better performance in rechargeable Zn-air batteries, including higher power density and better cycling stability. The developed synthetic approach opens up new avenues toward the development of sustainable active electrocatalysts for electrochemical energy devices.展开更多
Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-bas...Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-based nanomaterials,as the most promising substitute of platinum(Pt),exhibit superior activity and stability in ORR electrocatalysis.The delicate regulation of the structure and/or composition shows great potential in improving the electrocatalytic ORR performance of Pd-based nanomaterials.In this review,we retrospect the recent advance of Pdbased ORR electrocatalysts,and analyses the relationship between nanostructure and catalytic performance.We start with the ORR mechanism and indicators of ORR performance in both alkaline and acidic media,followed by the synthetic methods for Pd-based nanoparticles.Then,we emphasize the design strategies of efficient Pd-based ORR catalysts from the perspective of composition,crystal phase,morphology,and support effects.Last but not least,we conclude with possible opportunities and outlook on Pd-based nanomaterials toward ORR.展开更多
Designing highly active and durable electrocatalysts towards oxygen reduction reaction(ORR)plays a paramount importance for proton exchange membrane fuel cells.Pt-based binary alloys Pt-M(M=3d-transition metals)posses...Designing highly active and durable electrocatalysts towards oxygen reduction reaction(ORR)plays a paramount importance for proton exchange membrane fuel cells.Pt-based binary alloys Pt-M(M=3d-transition metals)possessing excellent electronic and geometric properties have received increasing interests as highly active electrocatalysts.Herein,we report a series of Pt_(x)Co/C(x=1,2,3)catalysts by a facile one-pot soft-chemistry method.In the acidic conditions,the mass activities of PtCo/C,Pt_(2)Co/C and Pt_(3)Co/C are 0.526,0.462 and 0.441 A·mgPt^(-1),which are 2.60,2.31 and 2.22 times higher than that of Pt/C(0.200 A·mgPt^(-1)),respectively.The specific activities of PtCo/C,Pt_(2)Co/C and Pt_(3)Co/C are 706.59,679.41 and 801.83μA·cm^(-2),which are accordingly 2.89,2.76 and 3.28 times higher than that of Pt/C(244.75μA·cm^(-2)).Notably,Pt_(3)Co/C shows a remarkable durability.After 5000 cycles of the accelerated durability testing,the mass activity and specific activity of Pt_(3)Co/C catalyst are 2.47 and 3.80 times higher than that of the commercial Pt/C,respectively.The improved ORR activity and durability can be ascribed to the synergistic interaction between Pt and Co.展开更多
For zinc air batteries,a non-noble metal-based electrocatalyst with a high performance and stability in oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)is imperative in application.Herein,a catalyst ba...For zinc air batteries,a non-noble metal-based electrocatalyst with a high performance and stability in oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)is imperative in application.Herein,a catalyst based on FeCo-N encapsuled in nitrogen-doped carbon nanotubes has been prepared,which provides an implementable method to design controlled structures with excellent bifunction al electrocatalytic activities.By adjusting the molar ratio of two metals,the synthesized FeCo-N-C catalyst delivers a competitive ORR and OER performance compared with commercial Pt/C and IrO_(2),performing a low overvoltage gap between ORR(E_(1/2))and OER(E_(j=10))of 0.8 V.Moreover,as a promising cathode in zinc air battery,the FeCo-N-C catalyst possesses an affirmative stability of over 100 h and large power density(129 mW·cm^(-2)).This work demonstrates that FeCo-N-C is one of the most promising catalysts for zinc air batteries and provides a possibility for exploration of batteries with high stability by adjusting the molar ratio of metals in the catalysts.展开更多
The main difficulty in the extensive commercial use of polymer electrolyte membrane fuel cells （PEMFCs） is the use of noble metals such as Pt-based electrocatalyst at the cathode, which is essential to ease the oxyg...The main difficulty in the extensive commercial use of polymer electrolyte membrane fuel cells （PEMFCs） is the use of noble metals such as Pt-based electrocatalyst at the cathode, which is essential to ease the oxygen reduction reaction （ORR） in fuel cells （FCs）. To eliminate the high loading of Pt-based electrocatalysts to minimize the cost, extensive study has been carried out over the previous decades on the non-noble metal catalysts. Development in enhancing the ORR performance of FCs is mainly due to the doped carbon materials, Fe and Co-based electrocatalysts, these materials could be considered as probable substitutes for Pt-based catalysts. But the stability of these non-noble metal electrocatalysts is low and the durability of these metals remains unclear. The three basic reasons of instability are： （i） oxidative occurrence by H2O2, （ii） leakage of the metal site and （iii） protonation by probable anion adsorption of the active site. Whereas leakage of the metal site has been almost solved, more work is required to understand and avoid losses from oxidative attack and protonation. The ORR performance such as stability tests are usually run at low current densities and the lifetime is much shorter than desired need. Therefore, improvement in the ORR activity and stability afe the key issues of the non-noble metal electrocatalyst. Based on the consequences obtained in this area, numerous future research directions are projected and discussed in this paper. Hence, this review is focused on improvement of stability and durability of the non-noble metal electrocatalyst.展开更多
Replacing fossil fuels with fuel cells is a feasible way to reduce global energy shortages and environmental pollution.However,the oxygen reduction reaction(ORR)at the cathode has sluggish kinetics,which limits the de...Replacing fossil fuels with fuel cells is a feasible way to reduce global energy shortages and environmental pollution.However,the oxygen reduction reaction(ORR)at the cathode has sluggish kinetics,which limits the development of fuel cells.It is significant to develop catalysts with high catalytic activity of ORR.The single-atom catalysts(SACs)of Pt supported on heteroatom-doped graphene are potential candidates for ORR.Here we studied the SACs of Pt with different heteroatoms doping and screened out Pt-C_(4) and Pt-C_(3)O_(1) structures with only 0.13 V overpotential for ORR.Meanwhile,it is found that B atoms doping could weaken the adsorption capacity of Pt,while N or O atoms doping could enhance it.This regularity was verified on Fe SACs.Through the electronic interaction analysis between Pt and adsorbate,we explained the mechanism of this regularity and further proposed a new descriptor named corrected d-band center(ε_(d-corr))to describe it.This descriptor is an appropriate reflection of the number of free electrons of the SACs,which could evaluate its adsorption capacity.Our work provides a purposeful regulatory strategy for the design of ORR catalysts.展开更多
Two-dimensional(2D)materials have attracted a great deal of research interest because of their unique electrical,magnetic,optical,mechanical,and catalytic properties for various applications.To date,however,it is stil...Two-dimensional(2D)materials have attracted a great deal of research interest because of their unique electrical,magnetic,optical,mechanical,and catalytic properties for various applications.To date,however,it is still difficult to fabricate most functional oxides as 2D materials unless they have a layered structure.Herein,we report a one-step universal strategy for preparing versatile non-layered oxide nanosheets by directly annealing the mixture of metal nitrate and dimethyl imidazole(2-MI).The 2-MI plays the key role for 2D oxides since 2-MI owns a very low molten point and sublimation temperature,in which its molten liquid can coordinate with metal ions,forming a metal-organic framework,and easily puffing by its gas molecules.A total of 17 materials were prepared by this strategy,including non-layered metal oxide nanosheets as well as metal/metal oxide loaded nitrogen-doped carbon nanosheets.The as-prepared cobalt particle-loaded nitrogen-doped carbon nanosheets(Co@N/C)exhibit remarkable bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalytic activity and durability.Besides,the Zn-air battery utilizing a Co@N/C catalyst exhibits high power density of 174.3 mW·cm^(-2).This facile strategy opens up a new way for large-scale synthesis of 2D oxides that holds great potential to push 2D oxides for practical applications.展开更多
Based on an experimental phenomenon that catalytic activity of Pt and Pd for oxygen reduction reaction (ORR) changes with catalyst supports from C to TiO2, density function theory (DFT) was used to elucidate the cause...Based on an experimental phenomenon that catalytic activity of Pt and Pd for oxygen reduction reaction (ORR) changes with catalyst supports from C to TiO2, density function theory (DFT) was used to elucidate the cause behind the difference in catalysis caused by catalyst supports. First, factors closely associated with the first electron transfer of the ORR were assessed in the light of quantum chemistry. Then intermediate (atomic oxygen, O) adsorption strength on the catalyst surface was calculated. The results show that, in terms of minimum energy difference, the best orbital symmetry match, and the maximum orbital overlap, TiO2 does bring about a very positive effect on catalysts Pd/TiO2 for the first electron transfer of the ORR. Especially, TiO2 remarkably expands the space size of Pd/TiO2 HOMO orbital and improves orbital overlap of Pd/TiO2 HOMO and O2 LUMO. The analysis of deformation density and partial density of state shows that the strong interaction between Pt and Ti leads to a strong adsorption of intermediate O on Pt/TiO2, but the strong interaction between Pd and surface O causes positive net charge of Pd and a weak adsorption of intermediate O on Pd/TiO2. Thus, the ORR can proceed more smoothly on Pd/TiO2 than Pt/TiO2 in every respect of maximum orbital overlap and rate delay by intermediate O. The research also discloses that several factors lead to less activity of TiO2-supported Pt and Pd catalysts than the C-supported ones for the ORR. These factors include the poor dispersion of Pt and Pd particles on TiO2, poor electric conduction of TiO2 carrier itself, and bigger energy difference between HOMO of TiO2-carried metallic catalysts and LUMO of O2 molecule due to electrons deeply embedded in the semiconductor TiO2 carrier.展开更多
The development of highly active and low-cost catalysts for electrochemical reactions is one of the most attractive topics in the renewable energy technology.Herein,the site-specific nitrogen doping of graphdiyne(GDY)...The development of highly active and low-cost catalysts for electrochemical reactions is one of the most attractive topics in the renewable energy technology.Herein,the site-specific nitrogen doping of graphdiyne(GDY)including grap-N,sp-N(Ⅰ)and sp-N(Ⅱ)GDY is systematically investigated as metal-free oxygen reduction electrocatalysts via density functional theory(DFT).Our results indicate that the doped nitrogen atom can significantly improve the oxygen(O2)adsorption activity of GDY through activating its neighboring carbon atoms.The free-energy landscape is employed to describe the electrochemical oxygen reduction reaction(ORR)in both O2 dissociation and association mechanisms.It is revealed that the association mechanism can provide higher ORR onset potential than dissociation mechanism on most of the substrates.Especially,sp-N(Ⅱ)GDY exhibits the highest ORR electrocatalytic activity through increasing the theoretical onset potential to 0.76 V.This work provides an atomic-level insight for the electrochemical ORR mechanism on metal-free N-doped GDY.展开更多
Development of active and durable electro- catalyst for oxygen reduction reaction （ORR） remains one challenge for the polymer electrolyte membrane fuel cell （PEMFC） technology. Pt-based nanomaterials show the grea...Development of active and durable electro- catalyst for oxygen reduction reaction （ORR） remains one challenge for the polymer electrolyte membrane fuel cell （PEMFC） technology. Pt-based nanomaterials show the greatest promise as electrocatalyst for this reaction among all current catalytic structures. This review focuses on Pt- based ORR catalyst material development and covers the past achievements, current research status and perspectives in this research field. In particular, several important categories of Pt-based catalytic structures and the research advances are summarized. Key factors affecting the catalyst activity and durability are discussed. An outlook of future research direction of ORR catalyst research is provided.展开更多
Atomically dispersed catalysts have attracted attention in energy conversion applications because their efficiency and chemoselectivity for special catalysis are superior to those of traditional catalysts. However, th...Atomically dispersed catalysts have attracted attention in energy conversion applications because their efficiency and chemoselectivity for special catalysis are superior to those of traditional catalysts. However, they have limitations owing to the extremely low metal-loading content on supports, difficulty in the precise control of the metal location and amount as well as low stability at high temperatures. We prepared a highly doped single metal atom hybrid via a single-step thermal pyrolysis of glucose, dicyandiamide, and inorganic metal salts. High-angle annular dark field-scanning transmission electron microscopy （HAADF-STEM） and X-ray absorption fine structure spectroscopy （XAFS） revealed that nitrogen atoms doped into the graphene matrix were pivotal for metal atom stabilization by generating a metal-Nx coordination structure. Due to the strong anchoring effect of the graphene matrix, the metal loading content was over 4 wt.% in the isolated atomic hybrid （the Pt content was as high as 9.26 wt.% in the Pt-doped hybrid）. Furthermore, the single iron-doped hybrid （Fe@N-doped graphene） showed a remarkable electrocatalytic performance for the oxygen reduction reaction. The peak power density was - 199 mW·cm-2 at a current density of 310 mA·cm-2 and superior to that of a commercial Pt/C catalyst when it was used as a cathode catalyst in assembled zinc-air batteries. This work offered a feasible approach to design and fabricate highly doped single metal atoms （SMAs） catalysts for potential energy applications.展开更多
The global practical implementation of proton exchange membrane fuel cells(PEMFCs)heavily relies on the advancement of highly effective platinum(Pt)-based electrocatalysts for the oxygen reduction reaction(ORR).To ach...The global practical implementation of proton exchange membrane fuel cells(PEMFCs)heavily relies on the advancement of highly effective platinum(Pt)-based electrocatalysts for the oxygen reduction reaction(ORR).To achieve high ORR performance,electrocatalysts with highly accessible reactive surfaces are needed to promote the uncovering of active positions for easy mass transportation.In this critical review,we introduce different approaches for the emerging development of effective ORR electrocatalysts,which offer high activity and durability.The strategies,including morphological engineering,geometric configuration modification via supporting materials,alloys regulation,core-shell,and confinement engineering of single atom electrocatalysts(SAEs),are discussed in line with the goals and requirements of ORR performance enhancement.We review the ongoing development of Pt electrocatalysts based on the syntheses,nanoarchitecture,electrochemical performances,and stability.We eventually explore the obstacles and research directions on further developing more effective electrocatalysts.展开更多
Single atom catalyst is of great importance for the oxygen reduction reaction(ORR).However,facile preparation of single atom catalyst without using well-designed precursors or labor-intensive acid leaching remains an ...Single atom catalyst is of great importance for the oxygen reduction reaction(ORR).However,facile preparation of single atom catalyst without using well-designed precursors or labor-intensive acid leaching remains an urgent challenge.Herein,a simple pyrolysis of Fe3+-loaded mesoporous phenolic resin(mPF)-melamine precursor is used to prepare the single atom iron-anchored N-doped mesoporous graphitic carbon nanospheres(Fe/N-MGN).Investigation of the synthesis reveals the appropriate Fe-assisted catalysis effect and mPF template effect,which not only spurs the highly graphitic porous framework of Fe/N-MGN with plentiful pyridinic N/graphitic N,but also assures the dispersed single atom Fe anchoring without elaborated procedures.As a result,the as-synthesized Fe/N-MGN demonstrates high catalytic activity,good durability and excellent methanol tolerance for ORR.This work promises a facile method to regulate the graphitic carbon growth and single atom Fe loading for the highly efficient electrocatalysis.展开更多
Rechargeable zinc-air batteries(ZABs)are currently receiving extensive attention because of their extremely high theoretical specific energy density,low manufacturing costs,and environmental friendliness.Exploring bif...Rechargeable zinc-air batteries(ZABs)are currently receiving extensive attention because of their extremely high theoretical specific energy density,low manufacturing costs,and environmental friendliness.Exploring bifunctional catalysts with high activity and stability to overcome sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction is critical for the development of rechargeable ZABs.Atomically dispersed metal-nitrogen-carbon(M-N-C)catalysts possessing prominent advantages of high metal atom utilization and electrocatalytic activity are promising candidates to promote oxygen electrocatalysis.In this work,general principles for designing atomically dispersed M-N-C are reviewed.Then,strategies aiming at enhancing the bifunctional catalytic activity and stability are presented.Finally,the challenges and perspectives of M-N-C bifunctional oxygen catalysts for ZABs are outlined.It is expected that this review will provide insights into the targeted optimization of atomically dispersed M-N-C catalysts in rechargeable ZABs.展开更多
In this study,the Lewis doping approach of polyaniline(PANI)was employed to fabricate cobait-nitrogen-carbon(Co-N-C)oxygen electrocatalysts for Zn-air batteries,aiming to enhance the active spots of Co-N-C.This result...In this study,the Lewis doping approach of polyaniline(PANI)was employed to fabricate cobait-nitrogen-carbon(Co-N-C)oxygen electrocatalysts for Zn-air batteries,aiming to enhance the active spots of Co-N-C.This resulting Co-N-C catalysts exhibited welldefined nanofiber networks,and the Brunauer-EmmettTeller(BET)analysis confirmed their substantial specific surface area.Electrochemical experiments demonstrated that the Co-N-C catalysts achieved the half-wave potential(vs.RHE)of 0.85 V in alkaline medium,overcoming Pt/C and iron-nitrogen-carbon(Fe-N-C)counterparts in extended cycle testing with only a 25 mV change in a half-wave potential after 5000 cycles.Remarkably,the highest power density measured in the zinc(Zn)-air battery reached 227 mW/cm2,a significant improvement over the performance of 101 mW/cm2 of the platinum on activated carbon(Pt/C)catalyst.These findings highlight the advantageous stability enhancement associated with the utilization of Co in the Co-N-C catalysts.展开更多
文摘Efficient oxygen electrocatalysts are the key elements of numerous energy storage and conversion devices, including fuel cells and metal-air batteries. In order to realize their practical applications, highly efficient and inexpensive non-noble metal-based oxygen electrocatalysts are urgently required. Herein, we report a novel iron-chelated urea-formaldehyde resin hydrogel for the synthesis of Fe-N-C electrocatalysts. This novel hydrogel is prepared using a new instantaneous （20 s） one-step scalable strategy, which theoretically ensures the atomic-level dispersion of Fe ions in the urea-formaldehyde resin, guaranteeing the microstructural homogeneity of the electrocatalyst. Consequentl~ the prepared electrocatalyst exhibits higher catalytic activity and durability in the oxygen reduction （ORR） and evolution （OER） reactions than the commercial Pt/C catalyst. Furthermore, the above catalyst also shows a much better performance in rechargeable Zn-air batteries, including higher power density and better cycling stability. The developed synthetic approach opens up new avenues toward the development of sustainable active electrocatalysts for electrochemical energy devices.
基金financially supported by the National Natural Science Foundation of China (No.52172058)。
文摘Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-based nanomaterials,as the most promising substitute of platinum(Pt),exhibit superior activity and stability in ORR electrocatalysis.The delicate regulation of the structure and/or composition shows great potential in improving the electrocatalytic ORR performance of Pd-based nanomaterials.In this review,we retrospect the recent advance of Pdbased ORR electrocatalysts,and analyses the relationship between nanostructure and catalytic performance.We start with the ORR mechanism and indicators of ORR performance in both alkaline and acidic media,followed by the synthetic methods for Pd-based nanoparticles.Then,we emphasize the design strategies of efficient Pd-based ORR catalysts from the perspective of composition,crystal phase,morphology,and support effects.Last but not least,we conclude with possible opportunities and outlook on Pd-based nanomaterials toward ORR.
基金financially supported by the Project of National Natural Science Foundation of China(No.5202780089)。
文摘Designing highly active and durable electrocatalysts towards oxygen reduction reaction(ORR)plays a paramount importance for proton exchange membrane fuel cells.Pt-based binary alloys Pt-M(M=3d-transition metals)possessing excellent electronic and geometric properties have received increasing interests as highly active electrocatalysts.Herein,we report a series of Pt_(x)Co/C(x=1,2,3)catalysts by a facile one-pot soft-chemistry method.In the acidic conditions,the mass activities of PtCo/C,Pt_(2)Co/C and Pt_(3)Co/C are 0.526,0.462 and 0.441 A·mgPt^(-1),which are 2.60,2.31 and 2.22 times higher than that of Pt/C(0.200 A·mgPt^(-1)),respectively.The specific activities of PtCo/C,Pt_(2)Co/C and Pt_(3)Co/C are 706.59,679.41 and 801.83μA·cm^(-2),which are accordingly 2.89,2.76 and 3.28 times higher than that of Pt/C(244.75μA·cm^(-2)).Notably,Pt_(3)Co/C shows a remarkable durability.After 5000 cycles of the accelerated durability testing,the mass activity and specific activity of Pt_(3)Co/C catalyst are 2.47 and 3.80 times higher than that of the commercial Pt/C,respectively.The improved ORR activity and durability can be ascribed to the synergistic interaction between Pt and Co.
基金financially supported by Gansu Provincial Natural Science Foundation of China(Nos.17JR5RA198,2020HZ-2)the Cooperation project of Gansu Academy of Sciences(No.2020HZ-2)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.lzujbky-2018-119,lzujbky-2018-ct08,lzujbky-2019-it23)the Key Areas Scientific and Technological Research Projects in Xinjiang Production and Construction Corps(No.2018AB004)。
文摘For zinc air batteries,a non-noble metal-based electrocatalyst with a high performance and stability in oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)is imperative in application.Herein,a catalyst based on FeCo-N encapsuled in nitrogen-doped carbon nanotubes has been prepared,which provides an implementable method to design controlled structures with excellent bifunction al electrocatalytic activities.By adjusting the molar ratio of two metals,the synthesized FeCo-N-C catalyst delivers a competitive ORR and OER performance compared with commercial Pt/C and IrO_(2),performing a low overvoltage gap between ORR(E_(1/2))and OER(E_(j=10))of 0.8 V.Moreover,as a promising cathode in zinc air battery,the FeCo-N-C catalyst possesses an affirmative stability of over 100 h and large power density(129 mW·cm^(-2)).This work demonstrates that FeCo-N-C is one of the most promising catalysts for zinc air batteries and provides a possibility for exploration of batteries with high stability by adjusting the molar ratio of metals in the catalysts.
基金supported by the National Natural Science Foundation of China(21306119)the Key Research and Development Projects in Sichuan Province(2017GZ0397,2017CC0017)+1 种基金the Science and Technology Project of Chengdu(2015-HM01-00531-SF)the Outstanding Young Scientist Foundation of Sichuan University(2013SCU04A23)
文摘The main difficulty in the extensive commercial use of polymer electrolyte membrane fuel cells （PEMFCs） is the use of noble metals such as Pt-based electrocatalyst at the cathode, which is essential to ease the oxygen reduction reaction （ORR） in fuel cells （FCs）. To eliminate the high loading of Pt-based electrocatalysts to minimize the cost, extensive study has been carried out over the previous decades on the non-noble metal catalysts. Development in enhancing the ORR performance of FCs is mainly due to the doped carbon materials, Fe and Co-based electrocatalysts, these materials could be considered as probable substitutes for Pt-based catalysts. But the stability of these non-noble metal electrocatalysts is low and the durability of these metals remains unclear. The three basic reasons of instability are： （i） oxidative occurrence by H2O2, （ii） leakage of the metal site and （iii） protonation by probable anion adsorption of the active site. Whereas leakage of the metal site has been almost solved, more work is required to understand and avoid losses from oxidative attack and protonation. The ORR performance such as stability tests are usually run at low current densities and the lifetime is much shorter than desired need. Therefore, improvement in the ORR activity and stability afe the key issues of the non-noble metal electrocatalyst. Based on the consequences obtained in this area, numerous future research directions are projected and discussed in this paper. Hence, this review is focused on improvement of stability and durability of the non-noble metal electrocatalyst.
基金supported by the National Key R&D Program of China(Nos.2022YFA1503100 and 2022YFA1503102)the National Natural Science Foundation of China(No.22273050)the Natural Science Foundation of Shandong Province(Nos.YDZX2021001 and ZR2022MB098).
文摘Replacing fossil fuels with fuel cells is a feasible way to reduce global energy shortages and environmental pollution.However,the oxygen reduction reaction(ORR)at the cathode has sluggish kinetics,which limits the development of fuel cells.It is significant to develop catalysts with high catalytic activity of ORR.The single-atom catalysts(SACs)of Pt supported on heteroatom-doped graphene are potential candidates for ORR.Here we studied the SACs of Pt with different heteroatoms doping and screened out Pt-C_(4) and Pt-C_(3)O_(1) structures with only 0.13 V overpotential for ORR.Meanwhile,it is found that B atoms doping could weaken the adsorption capacity of Pt,while N or O atoms doping could enhance it.This regularity was verified on Fe SACs.Through the electronic interaction analysis between Pt and adsorbate,we explained the mechanism of this regularity and further proposed a new descriptor named corrected d-band center(ε_(d-corr))to describe it.This descriptor is an appropriate reflection of the number of free electrons of the SACs,which could evaluate its adsorption capacity.Our work provides a purposeful regulatory strategy for the design of ORR catalysts.
基金supported by the National Key Research and Development Program of China(No.2022YFA1203500)the National Natural Science Foundation of China(Nos.51972124 and 51902115)the Opening Project of Hubei Key Laboratory of Biomass Fibers and Eco-Dyeing&Finishing(No.223009025).
文摘Two-dimensional(2D)materials have attracted a great deal of research interest because of their unique electrical,magnetic,optical,mechanical,and catalytic properties for various applications.To date,however,it is still difficult to fabricate most functional oxides as 2D materials unless they have a layered structure.Herein,we report a one-step universal strategy for preparing versatile non-layered oxide nanosheets by directly annealing the mixture of metal nitrate and dimethyl imidazole(2-MI).The 2-MI plays the key role for 2D oxides since 2-MI owns a very low molten point and sublimation temperature,in which its molten liquid can coordinate with metal ions,forming a metal-organic framework,and easily puffing by its gas molecules.A total of 17 materials were prepared by this strategy,including non-layered metal oxide nanosheets as well as metal/metal oxide loaded nitrogen-doped carbon nanosheets.The as-prepared cobalt particle-loaded nitrogen-doped carbon nanosheets(Co@N/C)exhibit remarkable bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalytic activity and durability.Besides,the Zn-air battery utilizing a Co@N/C catalyst exhibits high power density of 174.3 mW·cm^(-2).This facile strategy opens up a new way for large-scale synthesis of 2D oxides that holds great potential to push 2D oxides for practical applications.
基金Supported by the National Natural Science Foundation of China (Grant No. 20676156)the Chinese Ministry of Education (Grant No. 307021)+1 种基金the National 863 Program (Grant Nos. 2006AA11A141 and 2007AA05Z124)the Chongqing Sci &Tech Key Project (Grant No. CSTC2007AB6012)
文摘Based on an experimental phenomenon that catalytic activity of Pt and Pd for oxygen reduction reaction (ORR) changes with catalyst supports from C to TiO2, density function theory (DFT) was used to elucidate the cause behind the difference in catalysis caused by catalyst supports. First, factors closely associated with the first electron transfer of the ORR were assessed in the light of quantum chemistry. Then intermediate (atomic oxygen, O) adsorption strength on the catalyst surface was calculated. The results show that, in terms of minimum energy difference, the best orbital symmetry match, and the maximum orbital overlap, TiO2 does bring about a very positive effect on catalysts Pd/TiO2 for the first electron transfer of the ORR. Especially, TiO2 remarkably expands the space size of Pd/TiO2 HOMO orbital and improves orbital overlap of Pd/TiO2 HOMO and O2 LUMO. The analysis of deformation density and partial density of state shows that the strong interaction between Pt and Ti leads to a strong adsorption of intermediate O on Pt/TiO2, but the strong interaction between Pd and surface O causes positive net charge of Pd and a weak adsorption of intermediate O on Pd/TiO2. Thus, the ORR can proceed more smoothly on Pd/TiO2 than Pt/TiO2 in every respect of maximum orbital overlap and rate delay by intermediate O. The research also discloses that several factors lead to less activity of TiO2-supported Pt and Pd catalysts than the C-supported ones for the ORR. These factors include the poor dispersion of Pt and Pd particles on TiO2, poor electric conduction of TiO2 carrier itself, and bigger energy difference between HOMO of TiO2-carried metallic catalysts and LUMO of O2 molecule due to electrons deeply embedded in the semiconductor TiO2 carrier.
基金financial supports by the Young Scientists Fund of the National Natural Science Foundation of China (11604249)the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China (161008)+3 种基金the Foundation of the State Key Laboratory of Optical Fiber and Cable Manufacture Technology (SKLD1602)the State Key Laboratory of Refractors and Metallurgy (G201605), the Fundamental Research Funds for the Central Universities (2019-III-034)the Research Board of the State Key Laboratory of Silicate Materials for Architecturesfinancial supports and grants from Xiamen University Malaysia,the Xiamen University Malaysia Research Fund (XMUMRF/2019-C3/ IENG/0013)
文摘The development of highly active and low-cost catalysts for electrochemical reactions is one of the most attractive topics in the renewable energy technology.Herein,the site-specific nitrogen doping of graphdiyne(GDY)including grap-N,sp-N(Ⅰ)and sp-N(Ⅱ)GDY is systematically investigated as metal-free oxygen reduction electrocatalysts via density functional theory(DFT).Our results indicate that the doped nitrogen atom can significantly improve the oxygen(O2)adsorption activity of GDY through activating its neighboring carbon atoms.The free-energy landscape is employed to describe the electrochemical oxygen reduction reaction(ORR)in both O2 dissociation and association mechanisms.It is revealed that the association mechanism can provide higher ORR onset potential than dissociation mechanism on most of the substrates.Especially,sp-N(Ⅱ)GDY exhibits the highest ORR electrocatalytic activity through increasing the theoretical onset potential to 0.76 V.This work provides an atomic-level insight for the electrochemical ORR mechanism on metal-free N-doped GDY.
文摘Development of active and durable electro- catalyst for oxygen reduction reaction （ORR） remains one challenge for the polymer electrolyte membrane fuel cell （PEMFC） technology. Pt-based nanomaterials show the greatest promise as electrocatalyst for this reaction among all current catalytic structures. This review focuses on Pt- based ORR catalyst material development and covers the past achievements, current research status and perspectives in this research field. In particular, several important categories of Pt-based catalytic structures and the research advances are summarized. Key factors affecting the catalyst activity and durability are discussed. An outlook of future research direction of ORR catalyst research is provided.
基金This work is financially supported partly by Ministry of Science and Technology （MOST） （Nos. 2017YFA0303500 and 2014CB848900）, the National Natural Science Foundation of China （NSFC） （Nos. U1532112, 11574280 and 11605201 ）, CAS Interdisciplinary Innovation Team and CAS Key Research Program of Frontier Sciences （No. QYZDB-SSW-SLH018）. L. S. acknowledges the recruitment program of global experts, the CAS Hundred Talent Program and Key Laboratory of Advanced Energy Materials Chemistry （Ministry of Education） Nankai University. We thank the Shanghai Synchrotron Radiation Facility （14W1, SSRF）, the Beijing Synchrotron Radiation Facility （1W1B and soft-X-ray endstation, BSRF）, the Hefei Synchrotron Radiation Facility （Photoemission, MCD and Catalysis/ Surface Science Endstations, NSRL）, and the USTC Center for Micro and Nanoscale Research and Fabrication for helps in characterizations.
文摘Atomically dispersed catalysts have attracted attention in energy conversion applications because their efficiency and chemoselectivity for special catalysis are superior to those of traditional catalysts. However, they have limitations owing to the extremely low metal-loading content on supports, difficulty in the precise control of the metal location and amount as well as low stability at high temperatures. We prepared a highly doped single metal atom hybrid via a single-step thermal pyrolysis of glucose, dicyandiamide, and inorganic metal salts. High-angle annular dark field-scanning transmission electron microscopy （HAADF-STEM） and X-ray absorption fine structure spectroscopy （XAFS） revealed that nitrogen atoms doped into the graphene matrix were pivotal for metal atom stabilization by generating a metal-Nx coordination structure. Due to the strong anchoring effect of the graphene matrix, the metal loading content was over 4 wt.% in the isolated atomic hybrid （the Pt content was as high as 9.26 wt.% in the Pt-doped hybrid）. Furthermore, the single iron-doped hybrid （Fe@N-doped graphene） showed a remarkable electrocatalytic performance for the oxygen reduction reaction. The peak power density was - 199 mW·cm-2 at a current density of 310 mA·cm-2 and superior to that of a commercial Pt/C catalyst when it was used as a cathode catalyst in assembled zinc-air batteries. This work offered a feasible approach to design and fabricate highly doped single metal atoms （SMAs） catalysts for potential energy applications.
基金A.A.,G.H.,S.H.,A.L.,and X.Y.J.thank the financial support from Kempe Foundation(SMK21-0011,SMK21-0020)A.L.acknowledges Swedish Research Council(2019-03865)European Union’s Horizon Europe research and innovation program under grant agreement No.101086667.X.Y.J.thanks the financial support from Horizon-EIC and Pathfinder challenges,Grant Number:101070976.
文摘The global practical implementation of proton exchange membrane fuel cells(PEMFCs)heavily relies on the advancement of highly effective platinum(Pt)-based electrocatalysts for the oxygen reduction reaction(ORR).To achieve high ORR performance,electrocatalysts with highly accessible reactive surfaces are needed to promote the uncovering of active positions for easy mass transportation.In this critical review,we introduce different approaches for the emerging development of effective ORR electrocatalysts,which offer high activity and durability.The strategies,including morphological engineering,geometric configuration modification via supporting materials,alloys regulation,core-shell,and confinement engineering of single atom electrocatalysts(SAEs),are discussed in line with the goals and requirements of ORR performance enhancement.We review the ongoing development of Pt electrocatalysts based on the syntheses,nanoarchitecture,electrochemical performances,and stability.We eventually explore the obstacles and research directions on further developing more effective electrocatalysts.
基金This study was supported by the National Natural Science Foundation of China(Nos.21675032 and 81861138040)the Fundamental Research Funds for the Central Universities and DHU Distinguished Young Professor Program.We appreciate the kind help from Dr.Li Wang in Center of Analysis and Measurement,Fudan University for preparation of complicated samples and elemental analysis.
文摘Single atom catalyst is of great importance for the oxygen reduction reaction(ORR).However,facile preparation of single atom catalyst without using well-designed precursors or labor-intensive acid leaching remains an urgent challenge.Herein,a simple pyrolysis of Fe3+-loaded mesoporous phenolic resin(mPF)-melamine precursor is used to prepare the single atom iron-anchored N-doped mesoporous graphitic carbon nanospheres(Fe/N-MGN).Investigation of the synthesis reveals the appropriate Fe-assisted catalysis effect and mPF template effect,which not only spurs the highly graphitic porous framework of Fe/N-MGN with plentiful pyridinic N/graphitic N,but also assures the dispersed single atom Fe anchoring without elaborated procedures.As a result,the as-synthesized Fe/N-MGN demonstrates high catalytic activity,good durability and excellent methanol tolerance for ORR.This work promises a facile method to regulate the graphitic carbon growth and single atom Fe loading for the highly efficient electrocatalysis.
基金This work is supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)Centre Québéco is sur les Materiaux Fonctionnels(CQMF),Fonds de Recherche du Québec-Nature et Technologies(FRQNT)+2 种基金Institut National de la Recherche Scientifique(INRS)This work is also supported by the National Natural Science Foundation of China(21972017)the“Scientific and Technical Innovation Action Plan”Hong Kong,Macao and Taiwan Science&Technology Cooperation Project of Shanghai Science and Technology Committee(19160760600).F.Dong gratefully acknowledges scholarships from the China Scholarship Council(CSC).
文摘Rechargeable zinc-air batteries(ZABs)are currently receiving extensive attention because of their extremely high theoretical specific energy density,low manufacturing costs,and environmental friendliness.Exploring bifunctional catalysts with high activity and stability to overcome sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction is critical for the development of rechargeable ZABs.Atomically dispersed metal-nitrogen-carbon(M-N-C)catalysts possessing prominent advantages of high metal atom utilization and electrocatalytic activity are promising candidates to promote oxygen electrocatalysis.In this work,general principles for designing atomically dispersed M-N-C are reviewed.Then,strategies aiming at enhancing the bifunctional catalytic activity and stability are presented.Finally,the challenges and perspectives of M-N-C bifunctional oxygen catalysts for ZABs are outlined.It is expected that this review will provide insights into the targeted optimization of atomically dispersed M-N-C catalysts in rechargeable ZABs.
基金supported by the National Natural Science Foundation of China(Grant No.22279054).
文摘In this study,the Lewis doping approach of polyaniline(PANI)was employed to fabricate cobait-nitrogen-carbon(Co-N-C)oxygen electrocatalysts for Zn-air batteries,aiming to enhance the active spots of Co-N-C.This resulting Co-N-C catalysts exhibited welldefined nanofiber networks,and the Brunauer-EmmettTeller(BET)analysis confirmed their substantial specific surface area.Electrochemical experiments demonstrated that the Co-N-C catalysts achieved the half-wave potential(vs.RHE)of 0.85 V in alkaline medium,overcoming Pt/C and iron-nitrogen-carbon(Fe-N-C)counterparts in extended cycle testing with only a 25 mV change in a half-wave potential after 5000 cycles.Remarkably,the highest power density measured in the zinc(Zn)-air battery reached 227 mW/cm2,a significant improvement over the performance of 101 mW/cm2 of the platinum on activated carbon(Pt/C)catalyst.These findings highlight the advantageous stability enhancement associated with the utilization of Co in the Co-N-C catalysts.
