The photothermal conversion capacity of pristine organic phase change materials(PCMs)is inherently insufficient in solar energy utilization.To upgrade their photothermal conversion capacity,we developed bimetallic zeo...The photothermal conversion capacity of pristine organic phase change materials(PCMs)is inherently insufficient in solar energy utilization.To upgrade their photothermal conversion capacity,we developed bimetallic zeolitic imidazolate framework(ZIF)derived Co/N co-doped flower-like carbon(Co/N-FLC)-based composite PCMs toward solar energy harvesting.3D interconnected carbon framework with low interfacial thermal resistance,abundant carbon defects and high content of nitrogen doping,excellent localized surface plasmon resonance(LSPR)effect of Co nanoparticles,and light absorber Co_(3)ZnC in Co/N-FLC synergistically upgrade the photothermal capacity of(polyethylene glycol)PEG@Co/N-FLC composite PCMs with an ultrahigh photothermal conversion efficiency of 94.8%under 0.16 W/cm^(2).Uniformly anchored Co and Co_(3)ZnC nanoparticles in carbon framework guarantee excellent photon capture ability.Bridging carbon nanotubes(CNTs)in 2D carbon nanosheets further accelerate the rapid transport of phonons by constructing cross-connected heat transfer paths.Additionally,PEG@Co/N-FLC exhibits a thermal energy storage density of 100.69 J/g and excellent thermal stability and durable reliability.Therefore,PEG@Co/N-FLC composite PCMs are promising candidates to accelerate the efficient utilization of solar energy.展开更多
Potassium-ion batteries(KIBs)have great potential for applications in large-scale energy storage devices.However,the larger radius of K+leads to sluggish kinetics and inferior cycling performance,severely restricting ...Potassium-ion batteries(KIBs)have great potential for applications in large-scale energy storage devices.However,the larger radius of K+leads to sluggish kinetics and inferior cycling performance,severely restricting its practical applicability.Herein,we propose a rational strategy involving a Prussian blue analogue-derived graphitized carbon anode with fast and durable potassium storage capability,which is constructed by encapsulating cobalt nanoparticles in nitrogen-doped graphitized carbon(Co-NC).Both experimental and theoretical results show that N-doping effectively promotes the uniform dispersion of cobalt nanoparticles in the carbon matrix through Co-N bonds.Moreover,the cobalt nanoparticles and strong Co-N bonds synergistically form a threedimensional conductive network,increase the number of adsorption sites,and reduce the diffusion energy barrier,thereby facilitating the adsorption and the diffusion kinetics.These multiple effects lead to enhanced reversible capacities of 305 and 208.6 mAh g^−1 after 100 and 300 cycles at 0.05 and 0.1 A g^−1,respectively,demonstrating the applicability of the Co-NC anode for KIBs.展开更多
Poly(ionic liquids)(PILs)combined with the macromolecular structure and unique properties of ionic liquids show unlimited potential in catalysis.In this work,a series of metal-based PIL with different ionic ratios wer...Poly(ionic liquids)(PILs)combined with the macromolecular structure and unique properties of ionic liquids show unlimited potential in catalysis.In this work,a series of metal-based PIL with different ionic ratios were prepared for the selective oxidation of cyclohexane.Characterization analysis reveals that different degrees of ionization could adjust the Co-N sites of the catalysts efficiently,leading to significant changes in their electronic structure,which strongly relate to catalytic performance in oxidation.20.07%cyclohexane conversion and 13.06%cyclohexanone and cyclohexanol(KA oil)yield can be achieved by metal-based PILs that are better than other commercial catalysts.Compared with CoCl_(2),metal-based PILs perform well,with superior conversion and KA oil yield.More interestingly,the catalyst created in this study features a malleable Co-N site,which may potentially have an impact on how oxygen species adsorb and desorb from the catalyst.Therefore,the catalyst studied in this work is used as molecular oxygen for the selective oxidation of cyclohexane to produce KA oil,and its application prospect is promising.展开更多
The Fenton-like process shows promising potential to generate reactive oxygen species for the reme-diation of increasingly environmental pollutants.However,the slow development of high-activity cata-lysts with strong ...The Fenton-like process shows promising potential to generate reactive oxygen species for the reme-diation of increasingly environmental pollutants.However,the slow development of high-activity cata-lysts with strong stability and low leaching of metal ions has greatly inhibited scale-up application of this technology.Here,cobalt(Co)/nitrogen(N)atom co-curved carbon nanorod(CoNC)containing highly uniform CoN_(x)active sites is developed as a Fenton-like catalyst for the effective catalytic oxidation of various organics via peroxymonosulfate(PMS)activation with high stability.As confirmed by the exper-imental results,singlet oxygen(^(1)O_(2))is the dominant active species for the degradation of the organ-ics,with a proportion of 100%.Furthermore,density functional theory calculations indicate that CoN_(2)C_(2)is the most effective ligand structure with more negative adsorption energy for PMS and the shortest length Co-O bond,while the most reasonable generation pathway for^(1)O_(2)was CoN_(2)C_(2)-PMS→CoN_(2)C_(2)-OH∗→2O∗→^(1)O_(2).Further studies demonstrate that the electron can be transferred from the highest occupied molecular orbitals of the organics to the lowest unoccupied molecular orbitals of the PMS via CoN_(2)C_(2)action.In addition,the CoNC presents strong resistance to inorganic ions and natural organic matter in the Fenton-like catalysis process.The presence of CoN_(2)C_(2)active centre can significantly shorten the migration distance of the^(1)O_(2)generated from PMS activation,which further enhances the Fenton-like catalytic activity in terms of mineralising various organic contaminants with high efficiency over a wide pH range.展开更多
The high cost,scarcity,and poor stability of precious-metal-based catalysts have hindered their extensive application in energy conversion and storage.This stimulates the search for earth-abundant alternatives to repl...The high cost,scarcity,and poor stability of precious-metal-based catalysts have hindered their extensive application in energy conversion and storage.This stimulates the search for earth-abundant alternatives to replace noble metal electrocatalysts.Hence,in this study,we investigate a novel and low-cost bifunctional electrocatalyst consisting of ZnCoMnO_(4) anchored on nitrogen-doped graphene oxide(ZnCoMnO_(4)/N-rGO).Benefiting from the strong Co-N interaction in ZnCoMnO_(4) and the coupled conductive N-rGO,the catalysts exhibit high electrocatalytic activity.Moreover,density functional theory calculations support the dominant role of the strong Co-N electronic interaction,which leads to ZnCoMnO_(4)/N-rGO having more favorable binding energies with O2 and H_(2) O,resulting in fast reaction kinetics.The obtained ZnCoMnO_(4)/N-rGO electrocatalyst exhibits superb bifunctional activity,with a half-wave potential of 0.83 V for the oxygen reduction reaction and a low onset potential of 1.57 V for the oxygen evolution reaction in 0.1 M KOH solution.Furthermore,a Zn-air battery driven by the ZnCoMnO_(4)/N-rGO catalyst shows remarkable discharge/charge performance,with a power density of 138.52 mW cm^(-2) and longterm cycling stability for 48 h.This work provides a promising multifunctional electrocatalyst based on non-noble metals for the storage and conversion of renewable energy.展开更多
Oxygen reduction reaction （ORR） is key to fuel cells and metal-air batteries which are considered as the al- ternative clean energy. Various carbon materials have been widely researched as ORR electrocatalysts. It h...Oxygen reduction reaction （ORR） is key to fuel cells and metal-air batteries which are considered as the al- ternative clean energy. Various carbon materials have been widely researched as ORR electrocatalysts. It has been ac- cepted that heteroatom doping and exposure of the edge sites can effectively improve the activity of carbon materials. In this work, we used a simple method to prepare a novel N, P-dual doped carbon-based catalyst with many holes on the surface. In addition, trace level Co doping in the carbon material forming Co-N-C active species can further enhance the ORR performance. On one hand, the doping can adjust the elec- tronic structure of carbon atoms, which would induce more active sites for ORR. And on the other hand, the holes formed on the surface of carbon nanosheets would expose more edge sites and can improve the intrinsic activity of carbon. Due to the heteroatom doping and the exposed edge sites, the pre- pared carbon materials showed highly excellent ORR perfor- mance, dose to that of commercial Pt/C.展开更多
Over the past few years, electrocatalysis for the oxygen reduction reaction in alkaline solutions has undergone tremendous advances, and non-precious metal catalysts are of prime interest. In this study, we present a ...Over the past few years, electrocatalysis for the oxygen reduction reaction in alkaline solutions has undergone tremendous advances, and non-precious metal catalysts are of prime interest. In this study, we present a highly promising CoO@Co/N-C （where N-C represents a N-doped carbon material） catalyst, achieving an onset potential of 0.99 V （versus the reversible hydrogen electrode （RHE）） and a limiting current density of 7.07 mA-cm-2 （at 0.3 V versus RHE） at a rotation rate of 2,500 rpm in an O2-saturated 0.1 M KOH solution, comparable to a commercial Pt/C catalyst. The H2--O2 alkaline fuel cell test of CoO@Co/N-C as the cathode reveals a maximum power density of 237 mW.cm 2. Detailed investigation clarifies that a synergistic effect, induced by C-N, Co-N-C, and CoO/Co moieties, is responsible for the bulk of the gain in catalytic activity.展开更多
化石燃料的燃烧导致大气中二氧化碳(CO_(2))的浓度迅速上升,并引发了严重的能源、环境危机。由可再生电力驱动的电催化CO_(2)还原为增值化学品和燃料是解决当前化石燃料枯竭的一种有效方法。采用“一锅法”制备了磷(P)修饰的高分散性“...化石燃料的燃烧导致大气中二氧化碳(CO_(2))的浓度迅速上升,并引发了严重的能源、环境危机。由可再生电力驱动的电催化CO_(2)还原为增值化学品和燃料是解决当前化石燃料枯竭的一种有效方法。采用“一锅法”制备了磷(P)修饰的高分散性“钴-氮-碳”(Co-N-C/P)催化剂,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)等手段对催化剂的形貌、元素分布、缺陷程度、表面元素价态及配位结构进行了表征,并考察了其在H型电解槽中电催化CO_(2)还原为CO的性能。测试结果表明,所制备的Co-N-C/P催化剂在-0.9 V vs.RHE的外加电位下具有97.0%的CO法拉第效率(FE_(CO)),电流密度为4.58 mA/cm^(2),并可以进行26 h的稳定性测试。与Co-N-C催化剂相比,P的掺杂更有利于Co原子在碳黑基底上的良好分散,相应的FE_(CO)提高了约38.9%,说明P的掺杂有效提高了Co-N-C催化剂的电催化CO_(2)还原为CO的性能。展开更多
The rational and effective combination of multicomponent materials and ingenious microstructure design for efficient electromagnetic wave(EMW)absorption are still challenging.In this paper,MXene was used as the aeroge...The rational and effective combination of multicomponent materials and ingenious microstructure design for efficient electromagnetic wave(EMW)absorption are still challenging.In this paper,MXene was used as the aerogel matrix,modified with sea urchin-like magnetic Co/N-doped carbon@polyaniline(Co-NC@PANI),gelatin was introduced as the reinforcement phase of the aerogel backbone,and a microwave absorber with high efficiency and excellent performance was successfully prepared.The sea urchin-like Co-NC@PANI not only adjusted the impedance matching of the MXene but also introduced a magnetic loss mode into the composite.The multicomponent interfacial polarization,heterostructure,three-dimensional(3D)lightweight porous structure,and electromagnetic synergy strategy enabled the MXene-based aerogel modified by Co-NC@PANI(MCoP)to exhibit surprising EMW absorption properties.The maximum reflection loss(RL_(max))of the aerogel composite reached-62.4 dB,and the effective absorption bandwidth(EAB)reached 6.56 GHz when the loading was only 12%.In addition,through electromagnetic simulation experiments,the change in the electromagnetic field before and after EMW passed through the materials and the distribution of the volume loss density of EMW by the coaxial ring were observed.The coordinated electromagnetic balance strategy in the 3D network provides inspiration for the construction of materials and expands the research direction of lightweight and outstanding microwave absorbers.展开更多
Fe-nitrogen-carbon(Fe-N-C)-and Co-nitrogen-carbon(Co-N-C)-based electrocatalysts have been widely concerned because of their high OER/ORR activity,low metal cost,and simple preparation.The exploration of Fe-N-C and Co...Fe-nitrogen-carbon(Fe-N-C)-and Co-nitrogen-carbon(Co-N-C)-based electrocatalysts have been widely concerned because of their high OER/ORR activity,low metal cost,and simple preparation.The exploration of Fe-N-C and Co-N-C single atombased catalysts with high activity and stability to overcome the slow kinetics of oxygen reduction and oxygen evolution reactions is also the key to the development of efficient electrolytic water,fuel cells,and rechargeable metal-air batteries.Fe-N-C and Co-N-C single atom-based electrocatalysts have the advantages of a high utilization rate of metal atoms and high electrocatalytic activity,and are ideal catalysts for promoting electrochemical energy conversion and storage.The general principles of designing Fe-N-C and Co-N-C single atom-based electrocatalysts are reviewed in this paper.Then,the strategies to improve the bifunctional catalytic activity and stability are proposed.Finally,the challenges and prospects of Fe-N-C and Co-N-C single atom-based catalysts are well summarized.This review will provide a reference for the directed optimization of Fe-N-C and Co-N-C single atom-based catalysts.展开更多
Dual-metal catalysts with synergistic effect exhibit enormous potential for sustainable electrocatalytic applications and mechanism research.Compared with mono-metal-site catalysts,dual-metal-site catalysts exhibit hi...Dual-metal catalysts with synergistic effect exhibit enormous potential for sustainable electrocatalytic applications and mechanism research.Compared with mono-metal-site catalysts,dual-metal-site catalysts exhibit higher efficiency for the oxygen evolution reaction(OER)due to reduced energy barrier of the process involving proton-coupled multi-electron transfer.Herein,we construct dual-metal Fe-Co sites coordinated with nitrogen in graphene(FeCo-NG),which exhibits high OER performance with onset overpotential of only 126 mV and Tafel slope of 120 mV·dec^(−1),showing that the rate-determining step is controlled by the single-electron transfer step.Theoretical calculations reveal that the FeN_(4)site exhibits lower OER overpotential than the CoN_(4)site due to appropriate adsorption energy of OOH*on the former,while the O^(*)adsorbed on the adjacent Co site could stabilize the OOH*on the FeN_(4)site through hydrogen bond interaction.展开更多
基金Beijing Natural Science Foundation,Grant/Award Number:2232053National Natural Science Foundation of China,Grant/Award Number:51902025。
文摘The photothermal conversion capacity of pristine organic phase change materials(PCMs)is inherently insufficient in solar energy utilization.To upgrade their photothermal conversion capacity,we developed bimetallic zeolitic imidazolate framework(ZIF)derived Co/N co-doped flower-like carbon(Co/N-FLC)-based composite PCMs toward solar energy harvesting.3D interconnected carbon framework with low interfacial thermal resistance,abundant carbon defects and high content of nitrogen doping,excellent localized surface plasmon resonance(LSPR)effect of Co nanoparticles,and light absorber Co_(3)ZnC in Co/N-FLC synergistically upgrade the photothermal capacity of(polyethylene glycol)PEG@Co/N-FLC composite PCMs with an ultrahigh photothermal conversion efficiency of 94.8%under 0.16 W/cm^(2).Uniformly anchored Co and Co_(3)ZnC nanoparticles in carbon framework guarantee excellent photon capture ability.Bridging carbon nanotubes(CNTs)in 2D carbon nanosheets further accelerate the rapid transport of phonons by constructing cross-connected heat transfer paths.Additionally,PEG@Co/N-FLC exhibits a thermal energy storage density of 100.69 J/g and excellent thermal stability and durable reliability.Therefore,PEG@Co/N-FLC composite PCMs are promising candidates to accelerate the efficient utilization of solar energy.
基金supported by National Natural Science Foundation of China(Grant No.51932011,51802356)Innovation-Driven Project of Central South University(No.2020CX024)+3 种基金the Research Support Fund of the Collaborative Innovation Center of Manganese-Zinc-Vanadium Industrial Technology in Hunan Province(No.201809)the Program of Youth Talent Support for Hunan Province(2018RS3098)Hunan Provincial Innovation Foundation for Postgraduate(Grant No.CX2017B045)the Fundamental Research Funds for the Central Universities of Central South University(Grant No.2020zzts075).
文摘Potassium-ion batteries(KIBs)have great potential for applications in large-scale energy storage devices.However,the larger radius of K+leads to sluggish kinetics and inferior cycling performance,severely restricting its practical applicability.Herein,we propose a rational strategy involving a Prussian blue analogue-derived graphitized carbon anode with fast and durable potassium storage capability,which is constructed by encapsulating cobalt nanoparticles in nitrogen-doped graphitized carbon(Co-NC).Both experimental and theoretical results show that N-doping effectively promotes the uniform dispersion of cobalt nanoparticles in the carbon matrix through Co-N bonds.Moreover,the cobalt nanoparticles and strong Co-N bonds synergistically form a threedimensional conductive network,increase the number of adsorption sites,and reduce the diffusion energy barrier,thereby facilitating the adsorption and the diffusion kinetics.These multiple effects lead to enhanced reversible capacities of 305 and 208.6 mAh g^−1 after 100 and 300 cycles at 0.05 and 0.1 A g^−1,respectively,demonstrating the applicability of the Co-NC anode for KIBs.
基金supported by the National Science Fund for Excellent Young Scholars(22222813)Key Scientific and Technological Projects in Huizhou(2021JBZ5.1)the Joint Fund of Yulin University,and the Dalian National Laboratory for Clean Energy(Grant No.YLU-DNL Fund 2021016)
文摘Poly(ionic liquids)(PILs)combined with the macromolecular structure and unique properties of ionic liquids show unlimited potential in catalysis.In this work,a series of metal-based PIL with different ionic ratios were prepared for the selective oxidation of cyclohexane.Characterization analysis reveals that different degrees of ionization could adjust the Co-N sites of the catalysts efficiently,leading to significant changes in their electronic structure,which strongly relate to catalytic performance in oxidation.20.07%cyclohexane conversion and 13.06%cyclohexanone and cyclohexanol(KA oil)yield can be achieved by metal-based PILs that are better than other commercial catalysts.Compared with CoCl_(2),metal-based PILs perform well,with superior conversion and KA oil yield.More interestingly,the catalyst created in this study features a malleable Co-N site,which may potentially have an impact on how oxygen species adsorb and desorb from the catalyst.Therefore,the catalyst studied in this work is used as molecular oxygen for the selective oxidation of cyclohexane to produce KA oil,and its application prospect is promising.
基金This work was financially supported from the Key Program of National Natural Science Foundation of China(No.42030713)the National Natural Science Foundation of China(No.42007358)+4 种基金the Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515110518 and2021A1515110369)the Hongkong Schol-arship Program(No.XJ2020059)the China Postdoctoral Sci-ence Foundation(No.2019M663382)the Ministry of Science and Technology of China for State Key Research and Development Project(No.2016YFC0400702)the YoungInnovativeTalent Project of Guangdong Provincial Department of Education(No.2019GKQNCX056).The authors would like to thank Shiyanjia Lab(www.shiyanjia.com)for the GC-MS measurements.
文摘The Fenton-like process shows promising potential to generate reactive oxygen species for the reme-diation of increasingly environmental pollutants.However,the slow development of high-activity cata-lysts with strong stability and low leaching of metal ions has greatly inhibited scale-up application of this technology.Here,cobalt(Co)/nitrogen(N)atom co-curved carbon nanorod(CoNC)containing highly uniform CoN_(x)active sites is developed as a Fenton-like catalyst for the effective catalytic oxidation of various organics via peroxymonosulfate(PMS)activation with high stability.As confirmed by the exper-imental results,singlet oxygen(^(1)O_(2))is the dominant active species for the degradation of the organ-ics,with a proportion of 100%.Furthermore,density functional theory calculations indicate that CoN_(2)C_(2)is the most effective ligand structure with more negative adsorption energy for PMS and the shortest length Co-O bond,while the most reasonable generation pathway for^(1)O_(2)was CoN_(2)C_(2)-PMS→CoN_(2)C_(2)-OH∗→2O∗→^(1)O_(2).Further studies demonstrate that the electron can be transferred from the highest occupied molecular orbitals of the organics to the lowest unoccupied molecular orbitals of the PMS via CoN_(2)C_(2)action.In addition,the CoNC presents strong resistance to inorganic ions and natural organic matter in the Fenton-like catalysis process.The presence of CoN_(2)C_(2)active centre can significantly shorten the migration distance of the^(1)O_(2)generated from PMS activation,which further enhances the Fenton-like catalytic activity in terms of mineralising various organic contaminants with high efficiency over a wide pH range.
基金financially supported by the National Natural Science Foundation of China for Youths(No.21601067,21701057)the China Postdoctoral Science Foundation(No.2020 M673037)a project funded by the Priority Academic Program Development of the Jiangsu Higher Education Institutions。
文摘The high cost,scarcity,and poor stability of precious-metal-based catalysts have hindered their extensive application in energy conversion and storage.This stimulates the search for earth-abundant alternatives to replace noble metal electrocatalysts.Hence,in this study,we investigate a novel and low-cost bifunctional electrocatalyst consisting of ZnCoMnO_(4) anchored on nitrogen-doped graphene oxide(ZnCoMnO_(4)/N-rGO).Benefiting from the strong Co-N interaction in ZnCoMnO_(4) and the coupled conductive N-rGO,the catalysts exhibit high electrocatalytic activity.Moreover,density functional theory calculations support the dominant role of the strong Co-N electronic interaction,which leads to ZnCoMnO_(4)/N-rGO having more favorable binding energies with O2 and H_(2) O,resulting in fast reaction kinetics.The obtained ZnCoMnO_(4)/N-rGO electrocatalyst exhibits superb bifunctional activity,with a half-wave potential of 0.83 V for the oxygen reduction reaction and a low onset potential of 1.57 V for the oxygen evolution reaction in 0.1 M KOH solution.Furthermore,a Zn-air battery driven by the ZnCoMnO_(4)/N-rGO catalyst shows remarkable discharge/charge performance,with a power density of 138.52 mW cm^(-2) and longterm cycling stability for 48 h.This work provides a promising multifunctional electrocatalyst based on non-noble metals for the storage and conversion of renewable energy.
基金supported by the National Natural Science Foundation of China (21701043, 21573066, and 51402100)the Provincial Natural Science Foundation of Hunan (2016JJ1006 and 2016TP1009)the Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province and Shenzhen Science and Technology Program (JCYJ20170306141659388)
文摘Oxygen reduction reaction （ORR） is key to fuel cells and metal-air batteries which are considered as the al- ternative clean energy. Various carbon materials have been widely researched as ORR electrocatalysts. It has been ac- cepted that heteroatom doping and exposure of the edge sites can effectively improve the activity of carbon materials. In this work, we used a simple method to prepare a novel N, P-dual doped carbon-based catalyst with many holes on the surface. In addition, trace level Co doping in the carbon material forming Co-N-C active species can further enhance the ORR performance. On one hand, the doping can adjust the elec- tronic structure of carbon atoms, which would induce more active sites for ORR. And on the other hand, the holes formed on the surface of carbon nanosheets would expose more edge sites and can improve the intrinsic activity of carbon. Due to the heteroatom doping and the exposed edge sites, the pre- pared carbon materials showed highly excellent ORR perfor- mance, dose to that of commercial Pt/C.
文摘Over the past few years, electrocatalysis for the oxygen reduction reaction in alkaline solutions has undergone tremendous advances, and non-precious metal catalysts are of prime interest. In this study, we present a highly promising CoO@Co/N-C （where N-C represents a N-doped carbon material） catalyst, achieving an onset potential of 0.99 V （versus the reversible hydrogen electrode （RHE）） and a limiting current density of 7.07 mA-cm-2 （at 0.3 V versus RHE） at a rotation rate of 2,500 rpm in an O2-saturated 0.1 M KOH solution, comparable to a commercial Pt/C catalyst. The H2--O2 alkaline fuel cell test of CoO@Co/N-C as the cathode reveals a maximum power density of 237 mW.cm 2. Detailed investigation clarifies that a synergistic effect, induced by C-N, Co-N-C, and CoO/Co moieties, is responsible for the bulk of the gain in catalytic activity.
文摘化石燃料的燃烧导致大气中二氧化碳(CO_(2))的浓度迅速上升,并引发了严重的能源、环境危机。由可再生电力驱动的电催化CO_(2)还原为增值化学品和燃料是解决当前化石燃料枯竭的一种有效方法。采用“一锅法”制备了磷(P)修饰的高分散性“钴-氮-碳”(Co-N-C/P)催化剂,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)等手段对催化剂的形貌、元素分布、缺陷程度、表面元素价态及配位结构进行了表征,并考察了其在H型电解槽中电催化CO_(2)还原为CO的性能。测试结果表明,所制备的Co-N-C/P催化剂在-0.9 V vs.RHE的外加电位下具有97.0%的CO法拉第效率(FE_(CO)),电流密度为4.58 mA/cm^(2),并可以进行26 h的稳定性测试。与Co-N-C催化剂相比,P的掺杂更有利于Co原子在碳黑基底上的良好分散,相应的FE_(CO)提高了约38.9%,说明P的掺杂有效提高了Co-N-C催化剂的电催化CO_(2)还原为CO的性能。
文摘The rational and effective combination of multicomponent materials and ingenious microstructure design for efficient electromagnetic wave(EMW)absorption are still challenging.In this paper,MXene was used as the aerogel matrix,modified with sea urchin-like magnetic Co/N-doped carbon@polyaniline(Co-NC@PANI),gelatin was introduced as the reinforcement phase of the aerogel backbone,and a microwave absorber with high efficiency and excellent performance was successfully prepared.The sea urchin-like Co-NC@PANI not only adjusted the impedance matching of the MXene but also introduced a magnetic loss mode into the composite.The multicomponent interfacial polarization,heterostructure,three-dimensional(3D)lightweight porous structure,and electromagnetic synergy strategy enabled the MXene-based aerogel modified by Co-NC@PANI(MCoP)to exhibit surprising EMW absorption properties.The maximum reflection loss(RL_(max))of the aerogel composite reached-62.4 dB,and the effective absorption bandwidth(EAB)reached 6.56 GHz when the loading was only 12%.In addition,through electromagnetic simulation experiments,the change in the electromagnetic field before and after EMW passed through the materials and the distribution of the volume loss density of EMW by the coaxial ring were observed.The coordinated electromagnetic balance strategy in the 3D network provides inspiration for the construction of materials and expands the research direction of lightweight and outstanding microwave absorbers.
基金supported by NSFC(52373215)Sichuan Science and Technology Program(2023NSFSC0086)Fundamental Research Funds for the Central Universities(YJ2021156)。
文摘Fe-nitrogen-carbon(Fe-N-C)-and Co-nitrogen-carbon(Co-N-C)-based electrocatalysts have been widely concerned because of their high OER/ORR activity,low metal cost,and simple preparation.The exploration of Fe-N-C and Co-N-C single atombased catalysts with high activity and stability to overcome the slow kinetics of oxygen reduction and oxygen evolution reactions is also the key to the development of efficient electrolytic water,fuel cells,and rechargeable metal-air batteries.Fe-N-C and Co-N-C single atom-based electrocatalysts have the advantages of a high utilization rate of metal atoms and high electrocatalytic activity,and are ideal catalysts for promoting electrochemical energy conversion and storage.The general principles of designing Fe-N-C and Co-N-C single atom-based electrocatalysts are reviewed in this paper.Then,the strategies to improve the bifunctional catalytic activity and stability are proposed.Finally,the challenges and prospects of Fe-N-C and Co-N-C single atom-based catalysts are well summarized.This review will provide a reference for the directed optimization of Fe-N-C and Co-N-C single atom-based catalysts.
基金supported by the National Natural Science Foundation of China(Nos.22075099 and 31971322)the Education Department of Jilin Province(Nos.JJKH20220967KJ and JJKH20220968CY)+3 种基金the Natural Science Foundation of Jilin Province(No.20220101051JC)the Natural Science Foundation of Shaanxi Province(No.D5110220052)the Fundamental Research Funds for the Central Universities(No.D5000210743)Beijing Municipal Health Commission(No.2021-1G-1191).
文摘Dual-metal catalysts with synergistic effect exhibit enormous potential for sustainable electrocatalytic applications and mechanism research.Compared with mono-metal-site catalysts,dual-metal-site catalysts exhibit higher efficiency for the oxygen evolution reaction(OER)due to reduced energy barrier of the process involving proton-coupled multi-electron transfer.Herein,we construct dual-metal Fe-Co sites coordinated with nitrogen in graphene(FeCo-NG),which exhibits high OER performance with onset overpotential of only 126 mV and Tafel slope of 120 mV·dec^(−1),showing that the rate-determining step is controlled by the single-electron transfer step.Theoretical calculations reveal that the FeN_(4)site exhibits lower OER overpotential than the CoN_(4)site due to appropriate adsorption energy of OOH*on the former,while the O^(*)adsorbed on the adjacent Co site could stabilize the OOH*on the FeN_(4)site through hydrogen bond interaction.
