Nanocarbon materials have been used as important metal-free catalysts for various reactions including alkane dehydrogenation.However,clarifying the active sites and tuning the nanocarbon structure for direct dehydroge...Nanocarbon materials have been used as important metal-free catalysts for various reactions including alkane dehydrogenation.However,clarifying the active sites and tuning the nanocarbon structure for direct dehydrogenation have always been significantly challenging owing to the lack of fundamental understanding of the structure and surface properties of carbon materials.Herein,mesoporous carbon materials with different pore ordering and surface properties were synthesized through a soft-templating method with different formaldehyde/resorcinol ratios and carbonization temperatures and used for catalytic dehydrogenation of propane to propylene.The highly ordered mesoporous carbons were found to have higher catalytic activities than disordered and ordered mesoporous carbons,mainly because the highly ordered mesopores favor mass transportation and provide more accessible active sites.Furthermore,mesoporous carbons can provide a large amount of surface active sites owing to their high surface areas,which is favorable for propane dehydrogenation reaction.To control the surface oxygenated functional groups,highly ordered mesoporous carbons were carbonized at different temperatures(600,700,and 800℃).The propylene formation rates exhibit an excellent linear relationship with the number of ketonic C=O groups,suggesting that C=O groups are the most possible active sites.展开更多
The exploration of cost-effective non-noble-metal electrocatalysts is highly imperative to replace the state-of-the-art platinum-based catalysts for oxygen reduction reaction(ORR). Here, we prepared cobalt phosphonate...The exploration of cost-effective non-noble-metal electrocatalysts is highly imperative to replace the state-of-the-art platinum-based catalysts for oxygen reduction reaction(ORR). Here, we prepared cobalt phosphonate-derived N-doped cobalt phosphate/carbon nanotube hybrids(Co Pi C-N/CNTs) by hydrothermal treatment of N-containing cobalt phosphonate and oxidized carbon nanotubes(o-CNT) followed by high-temperature calcination under nitrogen atmosphere. The resultant Co Pi C-N/CNT exhibits a superior electrocatalytic performance for the ORR in alkaline media, which is equal to the commercial Pt/C catalyst in the aspect of half-wave potential, onset potential and diffuse limiting current density. Furthermore, the excellent tolerance to methanol and strong durability outperform those of commercial Pt/C. It is found that cobalt phosphonate-derived N-doped cobalt phosphate and the in-situ formed graphitic carbons play key roles on the activity enhancement. Besides, introducing a suitable amount of CNTs enhances the electronic conductivity and further contributes to the improved ORR performance.展开更多
Exploring cobalt phosphide catalysts with abundant active sites and outstanding intrinsic activity for active and robust hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is highly desirable.Herein,by ...Exploring cobalt phosphide catalysts with abundant active sites and outstanding intrinsic activity for active and robust hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is highly desirable.Herein,by the fine-tuning thermal-reduction treatment of cobalt phosphonates with spherical shape,the novel carbon-wrapped CoP-Co_(2)P polymorphs are rationally constructed.The unique hierarchical porous architecture and heterointerface of CoP-Co_(2)P not only increase active sites but also ensure intrinsic activity.The resultant catalyst exhibits significantly boosted HER activity in a wide pH range,for instance,a current density of 10 mA cm^(-2) at the overpotential of 81 mV in 0.5 mol L^(-1) H_(2)SO_(4),109 mV in 1.0 mol L^(-1) KOH,and 227 mV in 1.0 mol L^(-1) phosphate buffer saline,and remarkable OER activity(1.53 V@10 mA cm^(-2) in 1.0 mol L^(-1) KOH),associated with the impressive stability for each reaction.Moreover,serving as the bifunctional electrocatalysts in a two-electrode electrolyzer for overall water splitting,a low cell voltage of 1.60 V can deliver a current density of 10 mA cm^(-2) in 1.0 mol L^(-1) KOH.The structural evolution process of the CoP-Co_(2)P catalyst during electrolysis is thoroughly investigated.This work presents a new approach for designing and fabricating efficient and affordable metal phosphides for various electrochemical technologies.展开更多
基金supported by the National Natural Science Foundation of China(21421001,21573115)the Fundamental Research Funds for the Central Universities(63185015)the Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2017-K13)~~
文摘Nanocarbon materials have been used as important metal-free catalysts for various reactions including alkane dehydrogenation.However,clarifying the active sites and tuning the nanocarbon structure for direct dehydrogenation have always been significantly challenging owing to the lack of fundamental understanding of the structure and surface properties of carbon materials.Herein,mesoporous carbon materials with different pore ordering and surface properties were synthesized through a soft-templating method with different formaldehyde/resorcinol ratios and carbonization temperatures and used for catalytic dehydrogenation of propane to propylene.The highly ordered mesoporous carbons were found to have higher catalytic activities than disordered and ordered mesoporous carbons,mainly because the highly ordered mesopores favor mass transportation and provide more accessible active sites.Furthermore,mesoporous carbons can provide a large amount of surface active sites owing to their high surface areas,which is favorable for propane dehydrogenation reaction.To control the surface oxygenated functional groups,highly ordered mesoporous carbons were carbonized at different temperatures(600,700,and 800℃).The propylene formation rates exhibit an excellent linear relationship with the number of ketonic C=O groups,suggesting that C=O groups are the most possible active sites.
基金supported by the National Natural Science Foundation of China(21421001,21573115)~~
文摘The exploration of cost-effective non-noble-metal electrocatalysts is highly imperative to replace the state-of-the-art platinum-based catalysts for oxygen reduction reaction(ORR). Here, we prepared cobalt phosphonate-derived N-doped cobalt phosphate/carbon nanotube hybrids(Co Pi C-N/CNTs) by hydrothermal treatment of N-containing cobalt phosphonate and oxidized carbon nanotubes(o-CNT) followed by high-temperature calcination under nitrogen atmosphere. The resultant Co Pi C-N/CNT exhibits a superior electrocatalytic performance for the ORR in alkaline media, which is equal to the commercial Pt/C catalyst in the aspect of half-wave potential, onset potential and diffuse limiting current density. Furthermore, the excellent tolerance to methanol and strong durability outperform those of commercial Pt/C. It is found that cobalt phosphonate-derived N-doped cobalt phosphate and the in-situ formed graphitic carbons play key roles on the activity enhancement. Besides, introducing a suitable amount of CNTs enhances the electronic conductivity and further contributes to the improved ORR performance.
基金supported by the National Natural Science Foundation of China(21875118,22179065 and 22111530112)。
文摘Exploring cobalt phosphide catalysts with abundant active sites and outstanding intrinsic activity for active and robust hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is highly desirable.Herein,by the fine-tuning thermal-reduction treatment of cobalt phosphonates with spherical shape,the novel carbon-wrapped CoP-Co_(2)P polymorphs are rationally constructed.The unique hierarchical porous architecture and heterointerface of CoP-Co_(2)P not only increase active sites but also ensure intrinsic activity.The resultant catalyst exhibits significantly boosted HER activity in a wide pH range,for instance,a current density of 10 mA cm^(-2) at the overpotential of 81 mV in 0.5 mol L^(-1) H_(2)SO_(4),109 mV in 1.0 mol L^(-1) KOH,and 227 mV in 1.0 mol L^(-1) phosphate buffer saline,and remarkable OER activity(1.53 V@10 mA cm^(-2) in 1.0 mol L^(-1) KOH),associated with the impressive stability for each reaction.Moreover,serving as the bifunctional electrocatalysts in a two-electrode electrolyzer for overall water splitting,a low cell voltage of 1.60 V can deliver a current density of 10 mA cm^(-2) in 1.0 mol L^(-1) KOH.The structural evolution process of the CoP-Co_(2)P catalyst during electrolysis is thoroughly investigated.This work presents a new approach for designing and fabricating efficient and affordable metal phosphides for various electrochemical technologies.
