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
Heteroatom doping, precise composition control and rational morphology design are efficient strategies for producing novel nanocatalysts for the oxygen reduction reaction （ORR） in fuel cells. Herein, a cost-effectiv...Heteroatom doping, precise composition control and rational morphology design are efficient strategies for producing novel nanocatalysts for the oxygen reduction reaction （ORR） in fuel cells. Herein, a cost-effective approach to synthesize nitrogen- and sulfur-codoped carbon nanowire aerogels using a hard templating method is proposed. The aerogels prepared using a combination of hydrothermal treatment and carbonization exhibit good catalytic activity for the ORR in alkaline solution. At the optimal annealing temperature and mass ratio between the nitrogen and sulfur precursors, the resultant aerogels show comparable electrocatalytic activity to that of a commercial Pt/C catalyst for the ORR. Importantly, the optimized catalyst shows much better long-term stability and satisfactory tolerance for the methanol crossover effect. These codoped aerogels are expected to have potential applications in fuel cells.展开更多
Tirazine based microporous polymeric (TMP) network was found to be an efficient metal-free catalyst for the epoxidation of styrene. The reactions were performed in water as an environmentally benign medium using H2O2 ...Tirazine based microporous polymeric (TMP) network was found to be an efficient metal-free catalyst for the epoxidation of styrene. The reactions were performed in water as an environmentally benign medium using H2O2 as a green oxidant at ambient temperature. The reaction afforded higher yield with 90% conversion of styrene and 98% selectivity to styrene oxide in 6 h. The triazine based microporous polymeric network can be readily recovered and reused up to 4 cycles without significant loss in catalytic activity and selectivity.展开更多
On the basis of the FLP (frustrated Lewis pair) principle, a new strategy has been proposed to construct the "frustration" in de- signing metal-free hydrogen activation compounds, by using FMO (frontier mole...On the basis of the FLP (frustrated Lewis pair) principle, a new strategy has been proposed to construct the "frustration" in de- signing metal-free hydrogen activation compounds, by using FMO (frontier molecular orbital) analyses and quantum mechanics calculations. Unlike the known FLPs which use bulky substituents to prevent them from forming stable Lewis acid/base com- plexes, the new approach encumbers the intramolecular π donation from the electron donor to the acceptor (e.g. in BH2NH2) by using a CH2 bridge (giving BH2CH2NH2). The strategy is simple and effective. Its effectiveness is demonstrated by the small hy- drogen activation energy (12.0 kcal/mol) of the model molecule (BH2CH2NH2), which is significantly less than the 42.7 kcal/mol of BH2NH2 and also less than the 18.5 kcal/mol of BH2PH2 whose derivative, R2PB(C6F5)2, has been experimentally shown to be able to activate hydrogen. We also exemplified how to use the strategy to design experimentally more realizable molecules. The example shows promises as a hydrogen activation agent. The strategy can be used to design metal-free catalysts for direct hydro-genation.展开更多
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Heteroatom doping, precise composition control and rational morphology design are efficient strategies for producing novel nanocatalysts for the oxygen reduction reaction （ORR） in fuel cells. Herein, a cost-effective approach to synthesize nitrogen- and sulfur-codoped carbon nanowire aerogels using a hard templating method is proposed. The aerogels prepared using a combination of hydrothermal treatment and carbonization exhibit good catalytic activity for the ORR in alkaline solution. At the optimal annealing temperature and mass ratio between the nitrogen and sulfur precursors, the resultant aerogels show comparable electrocatalytic activity to that of a commercial Pt/C catalyst for the ORR. Importantly, the optimized catalyst shows much better long-term stability and satisfactory tolerance for the methanol crossover effect. These codoped aerogels are expected to have potential applications in fuel cells.
文摘Tirazine based microporous polymeric (TMP) network was found to be an efficient metal-free catalyst for the epoxidation of styrene. The reactions were performed in water as an environmentally benign medium using H2O2 as a green oxidant at ambient temperature. The reaction afforded higher yield with 90% conversion of styrene and 98% selectivity to styrene oxide in 6 h. The triazine based microporous polymeric network can be readily recovered and reused up to 4 cycles without significant loss in catalytic activity and selectivity.
基金supported by the Hundred Talents Program of the Chinese Academy of Sciences and Nationd Nataral Science Foundation of China (Grant No.20773160)
文摘On the basis of the FLP (frustrated Lewis pair) principle, a new strategy has been proposed to construct the "frustration" in de- signing metal-free hydrogen activation compounds, by using FMO (frontier molecular orbital) analyses and quantum mechanics calculations. Unlike the known FLPs which use bulky substituents to prevent them from forming stable Lewis acid/base com- plexes, the new approach encumbers the intramolecular π donation from the electron donor to the acceptor (e.g. in BH2NH2) by using a CH2 bridge (giving BH2CH2NH2). The strategy is simple and effective. Its effectiveness is demonstrated by the small hy- drogen activation energy (12.0 kcal/mol) of the model molecule (BH2CH2NH2), which is significantly less than the 42.7 kcal/mol of BH2NH2 and also less than the 18.5 kcal/mol of BH2PH2 whose derivative, R2PB(C6F5)2, has been experimentally shown to be able to activate hydrogen. We also exemplified how to use the strategy to design experimentally more realizable molecules. The example shows promises as a hydrogen activation agent. The strategy can be used to design metal-free catalysts for direct hydro-genation.
