Understanding the intrinsic activity of oxygen evolution reaction(OER) is crucial for catalyst design.To date,different metal-doping strategies have been developed to achieve this,but the involving mechanisms remain u...Understanding the intrinsic activity of oxygen evolution reaction(OER) is crucial for catalyst design.To date,different metal-doping strategies have been developed to achieve this,but the involving mechanisms remain unclear.Here,the electronic structure of the transition metal-doped NiFe_(2)O_(4)(001) surface is scrutinized for OER intrinsic activity using density functional theory calculations.Five 3d-orbital filling metals(Ti,V,Cr,Mn,and Co) are introduced as dopants onto A-and B-layers of the NiFe_(2)O_(4)(001) surface,and variation of oxidation states over Fe sites is observed on B-layer.Analyzing the magnetic moment and charge transfer of surface cation sites reveals that the variation of Fe oxidation states originates from the super-exchange effect and is influenced by the t2g-electron configuration of 3d metal dopants.This trend governs the generation of highly-active Fe3+sites on the B-layer,the adsorption strength of OER intermediates,i.e.,*O and*OH,and therefore the intrinsic activity.The finding of super-exchange mechanism induced by 3d early metal doping offers insights into electronic structure tailoring strategies for improving the intrinsic activity of OER electrocatalysts.展开更多
Rational design of catalytic sites to activate the inert N≡N bond is of paramount importance to advance N2 electroreduction. Here, guided by the theoretical predictions, we construct a NiFe layered double hydroxide (...Rational design of catalytic sites to activate the inert N≡N bond is of paramount importance to advance N2 electroreduction. Here, guided by the theoretical predictions, we construct a NiFe layered double hydroxide (NiFe-LDH) nanosheet catalyst with a high density of electron-deficient sites, which were achieved by introducing oxygen vacancies in NiFe-LDH. Density functional theory calculations indicate that the electron-deficient sites show a much lower energy barrier (0.76 eV) for the potential determining step compared with that of the pristine NiFe-LDH (2.02 eV). Benefiting from this, the NiFe-LDH with oxygen vacancies exhibits the greatly improved electrocatalytic activity, presenting a high NH3 yield rate of 19.44 µg·h−1·mgcat−1, Faradaic efficiency of 19.41% at −0.20 V vs. reversible hydrogen electrode (RHE) in 0.1 M KOH electrolyte, as well as the outstanding stability. The present work not only provides an active electrocatalyst toward N2 reduction but also offers a facile strategy to boost the N2 reduction.展开更多
基金supported by the Australian Research Council(FT170100224,DP210103892,IC200100023)support from Tsinghua National Laboratory for Information Science and Technology for theoretical simulations。
文摘Understanding the intrinsic activity of oxygen evolution reaction(OER) is crucial for catalyst design.To date,different metal-doping strategies have been developed to achieve this,but the involving mechanisms remain unclear.Here,the electronic structure of the transition metal-doped NiFe_(2)O_(4)(001) surface is scrutinized for OER intrinsic activity using density functional theory calculations.Five 3d-orbital filling metals(Ti,V,Cr,Mn,and Co) are introduced as dopants onto A-and B-layers of the NiFe_(2)O_(4)(001) surface,and variation of oxidation states over Fe sites is observed on B-layer.Analyzing the magnetic moment and charge transfer of surface cation sites reveals that the variation of Fe oxidation states originates from the super-exchange effect and is influenced by the t2g-electron configuration of 3d metal dopants.This trend governs the generation of highly-active Fe3+sites on the B-layer,the adsorption strength of OER intermediates,i.e.,*O and*OH,and therefore the intrinsic activity.The finding of super-exchange mechanism induced by 3d early metal doping offers insights into electronic structure tailoring strategies for improving the intrinsic activity of OER electrocatalysts.
基金This work was supported by the National Natural Science Foundation of China (No. 21603208)Shenzhen Science and Technology Project (Nos. JCYJ20170412105400428 and JCYJ20180507182246321)+3 种基金Shenzhen Peacock Technological Innovation Project (No. KQJSCX20170727101208249)Fundamental Research Funds for the Central Universities, the Open Project Program of the State Key Laboratory of Silicon Materials, Zhejiang University, and China Postdoctoral Science Foundation (No. 2019M663058)This research was undertaken with the assistance of resources provided by the National Computational Infrastructure (NCI) facility at the Australian National Universityallocated through both the National Computational Merit Allocation Scheme supported by the Australian Government and the Australian Research Council grant LE190100021 (Sustaining and strengthening merit-based access at NCI, 2019–2021).
文摘Rational design of catalytic sites to activate the inert N≡N bond is of paramount importance to advance N2 electroreduction. Here, guided by the theoretical predictions, we construct a NiFe layered double hydroxide (NiFe-LDH) nanosheet catalyst with a high density of electron-deficient sites, which were achieved by introducing oxygen vacancies in NiFe-LDH. Density functional theory calculations indicate that the electron-deficient sites show a much lower energy barrier (0.76 eV) for the potential determining step compared with that of the pristine NiFe-LDH (2.02 eV). Benefiting from this, the NiFe-LDH with oxygen vacancies exhibits the greatly improved electrocatalytic activity, presenting a high NH3 yield rate of 19.44 µg·h−1·mgcat−1, Faradaic efficiency of 19.41% at −0.20 V vs. reversible hydrogen electrode (RHE) in 0.1 M KOH electrolyte, as well as the outstanding stability. The present work not only provides an active electrocatalyst toward N2 reduction but also offers a facile strategy to boost the N2 reduction.
