锌-空气电池(ZAB)因其能量密度高、环境友好、成本低以及安全性高而备受关注.然而,空气电极上的氧还原反应(ORR)动力学缓慢,严重限制了ZAB的输出功率.尽管铂基催化剂展现出优异的ORR催化活性,但高昂的成本制约其大规模商业化应用.因此,...锌-空气电池(ZAB)因其能量密度高、环境友好、成本低以及安全性高而备受关注.然而,空气电极上的氧还原反应(ORR)动力学缓慢,严重限制了ZAB的输出功率.尽管铂基催化剂展现出优异的ORR催化活性,但高昂的成本制约其大规模商业化应用.因此,迫切需要开发高效、低成本的ORR电催化剂.研究表明,具有原子分散Co-N4活性位点的Co-N-C单原子催化剂是理想的ORR非贵金属催化剂,但其仍然存在与反应关键中间体结合能较高的难题.目前的研究主要通过调控单原子配位环境与增大活性位点密度来提高Co-N-C催化剂的活性,但如何精确控制中心金属电子结构以及避免高温下金属原子的团聚仍面临巨大挑战.除了单原子活性位点外,催化剂载体的键合结构、电荷分布状态亦会影响载体本身和单原子位点的催化活性.然而,现有的研究主要聚焦于单原子位点或无金属催化剂单方面活性的提升,关于它们之间的相互作用对于催化性能影响的研究相对很少.为了进一步提高Co单原子催化剂的催化活性,本文通过简单的模板法与NH3二次处理策略制备了氮掺杂缺陷碳负载的Co-N_(5)位点单原子催化剂.电感耦合等离子体发射光谱结果表明,单原子Co的金属负载量高达2.57 wt%.此外,相比于未经过NH3二次处理的Co-Nx/HC样品,Co-N_(5)/DHC样品在电子顺磁共振谱中g=2.003处呈现出更明显的共振信号,在C 1s高分辨谱中具有更低的C-C(sp2杂化)/C-N(sp3杂化)比例以及明显增加的吡啶氮信号,证实了Co-N_(5)/DHC显著提升的氮掺杂碳缺陷浓度并具有丰富的边界/缺陷位点.同时,X射线吸收谱与球差矫正透射电子显微镜结果表明所制备的样品为原子分散的Co-N_(5)结构,从而证明成功制备了缺陷氮掺杂碳耦合Co-N_(5)位点单原子催化剂.电化学测试结果表明,缺陷氮掺杂碳耦合Co-N_(5)位点后表现较好的ORR性能,半波电位达到0.877 V,明显高于Co-Nx/HC对比样品和商业化Pt/C催化剂.Koutecky-Levich曲线和旋转盘环电极测试结果表明,Co-N_(5)/DHC催化剂的高效4e-反应路径.且在10000次的加速老化测试中,Co-N_(5)/DHC半波电位仅降低了7 m V,稳定性优于Pt/C.以Co-N_(5)/DHC为阴极催化剂组装的ZAB开路电压为1.45 V,峰值输出功率密度能够达到160.7 m W cm^(-2),并能提供766.2 m A h gZn-1的比容量,展现出较高的应用前景.密度泛函理论计算表明,Co-N_(5)位点与缺陷氮掺杂碳的相互作用诱导Co中心位点电子的重新分布,降低了ORR反应能垒.综上,本文为设计与合成高性能的Co单原子催化剂,用于先进的可再生能源转换系统提供了一种新思路.展开更多
Engineering non-precious metals into nitrogen-doped carbon is employed to improve electrocatalyst activity towards oxygen reduction reaction(ORR). A nickel-doped Co-N/C mesoporous nanopolyhedron is successfully evolut...Engineering non-precious metals into nitrogen-doped carbon is employed to improve electrocatalyst activity towards oxygen reduction reaction(ORR). A nickel-doped Co-N/C mesoporous nanopolyhedron is successfully evoluted from a Ni-doped ZIF-67 precursor. The Ni & Co synergistic N/C catalyst exhibits a half-wave potential of 0.895 V(vs. reversible hydrogen electrode(RHE)) with a diffusion-limiting current density of 6.1 m A cm^(-2)for alkaline ORR at 1600 r min^(-1), which is competitive to commercial Pt/C in terms of cost, methanol tolerance, and long-term stability. In situ surface-enhanced Raman scattering(SERS) study reveals the formation and fast conversion of superoxide ion(O_(2)^(-)) intermediate on the catalyst surface. Density functional theory(DFT) calculations demonstrate the decrease of energy barrier for potential-determining step(O* protonation) by Co-Ni synergy as well as the reduction of adsorption energy on catalyst surface upon nickel doping. The joint results of in situ SERS study and DFT calculations suggest a favourable ORR process on nickel-doped Co-N/C.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
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
A new ab initio potential energy surface of the Ne-CO complex is developed using single and double excitation coupled-cluster theory with noniterative treatment of triple excitations [CCSD（T）]. The potential has a m...A new ab initio potential energy surface of the Ne-CO complex is developed using single and double excitation coupled-cluster theory with noniterative treatment of triple excitations [CCSD（T）]. The potential has a minimum value of -49.396 cm-1 at Re = 6.40α0 with approximately T-shaped geometry （θe=82.5°）. Bound state energies are calculated up to J = 12. The theoretically predicted transition frequencies and spectroscopic constants are in good agreement with the available experimental results.展开更多
文摘锌-空气电池(ZAB)因其能量密度高、环境友好、成本低以及安全性高而备受关注.然而,空气电极上的氧还原反应(ORR)动力学缓慢,严重限制了ZAB的输出功率.尽管铂基催化剂展现出优异的ORR催化活性,但高昂的成本制约其大规模商业化应用.因此,迫切需要开发高效、低成本的ORR电催化剂.研究表明,具有原子分散Co-N4活性位点的Co-N-C单原子催化剂是理想的ORR非贵金属催化剂,但其仍然存在与反应关键中间体结合能较高的难题.目前的研究主要通过调控单原子配位环境与增大活性位点密度来提高Co-N-C催化剂的活性,但如何精确控制中心金属电子结构以及避免高温下金属原子的团聚仍面临巨大挑战.除了单原子活性位点外,催化剂载体的键合结构、电荷分布状态亦会影响载体本身和单原子位点的催化活性.然而,现有的研究主要聚焦于单原子位点或无金属催化剂单方面活性的提升,关于它们之间的相互作用对于催化性能影响的研究相对很少.为了进一步提高Co单原子催化剂的催化活性,本文通过简单的模板法与NH3二次处理策略制备了氮掺杂缺陷碳负载的Co-N_(5)位点单原子催化剂.电感耦合等离子体发射光谱结果表明,单原子Co的金属负载量高达2.57 wt%.此外,相比于未经过NH3二次处理的Co-Nx/HC样品,Co-N_(5)/DHC样品在电子顺磁共振谱中g=2.003处呈现出更明显的共振信号,在C 1s高分辨谱中具有更低的C-C(sp2杂化)/C-N(sp3杂化)比例以及明显增加的吡啶氮信号,证实了Co-N_(5)/DHC显著提升的氮掺杂碳缺陷浓度并具有丰富的边界/缺陷位点.同时,X射线吸收谱与球差矫正透射电子显微镜结果表明所制备的样品为原子分散的Co-N_(5)结构,从而证明成功制备了缺陷氮掺杂碳耦合Co-N_(5)位点单原子催化剂.电化学测试结果表明,缺陷氮掺杂碳耦合Co-N_(5)位点后表现较好的ORR性能,半波电位达到0.877 V,明显高于Co-Nx/HC对比样品和商业化Pt/C催化剂.Koutecky-Levich曲线和旋转盘环电极测试结果表明,Co-N_(5)/DHC催化剂的高效4e-反应路径.且在10000次的加速老化测试中,Co-N_(5)/DHC半波电位仅降低了7 m V,稳定性优于Pt/C.以Co-N_(5)/DHC为阴极催化剂组装的ZAB开路电压为1.45 V,峰值输出功率密度能够达到160.7 m W cm^(-2),并能提供766.2 m A h gZn-1的比容量,展现出较高的应用前景.密度泛函理论计算表明,Co-N_(5)位点与缺陷氮掺杂碳的相互作用诱导Co中心位点电子的重新分布,降低了ORR反应能垒.综上,本文为设计与合成高性能的Co单原子催化剂,用于先进的可再生能源转换系统提供了一种新思路.
基金supported by the National Natural Science Foundation of China (No. 21874053)the Science and Technology Development Project of Jilin Province, China (No. 20180414022GH)funding from the Advanced Low Carbon Technology Research and Development Program (ALCA), specially promoted research for innovative nextgeneration batteries (SPRING)。
文摘Engineering non-precious metals into nitrogen-doped carbon is employed to improve electrocatalyst activity towards oxygen reduction reaction(ORR). A nickel-doped Co-N/C mesoporous nanopolyhedron is successfully evoluted from a Ni-doped ZIF-67 precursor. The Ni & Co synergistic N/C catalyst exhibits a half-wave potential of 0.895 V(vs. reversible hydrogen electrode(RHE)) with a diffusion-limiting current density of 6.1 m A cm^(-2)for alkaline ORR at 1600 r min^(-1), which is competitive to commercial Pt/C in terms of cost, methanol tolerance, and long-term stability. In situ surface-enhanced Raman scattering(SERS) study reveals the formation and fast conversion of superoxide ion(O_(2)^(-)) intermediate on the catalyst surface. Density functional theory(DFT) calculations demonstrate the decrease of energy barrier for potential-determining step(O* protonation) by Co-Ni synergy as well as the reduction of adsorption energy on catalyst surface upon nickel doping. The joint results of in situ SERS study and DFT calculations suggest a favourable ORR process on nickel-doped Co-N/C.
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.
文摘A new ab initio potential energy surface of the Ne-CO complex is developed using single and double excitation coupled-cluster theory with noniterative treatment of triple excitations [CCSD（T）]. The potential has a minimum value of -49.396 cm-1 at Re = 6.40α0 with approximately T-shaped geometry （θe=82.5°）. Bound state energies are calculated up to J = 12. The theoretically predicted transition frequencies and spectroscopic constants are in good agreement with the available experimental results.
