Co(OH)_(2)/CoN的界面空位协同作用促进碱性水分解

Interface-vacancy synergy of Co(OH)_(2)/CoN to boost alkaline water splitting

开发高性能、稳定的双功能电催化剂是一个具有挑战性的课题.本工作基于界面工程和空位工程,通过电沉积成功构建了一种富含氧空位的异质结催化剂.所制备的催化剂V_(O)-Co(OH)_(2)/CoN在碱性电解质中具有良好的双功能催化活性和稳定性,在10 mA cm^(-2)条件下,析氢反应的过电位为52 mV,析氧反应的过电位为206 mV,且其全水分解电压仅为1.518 V.更重要的是,实验和密度泛函理论计算都证实了V_(O)-Co(OH)_(2)/CoN优异的双功能活性归因于异质界面和氧空位的协同催化.在异质界面附近,一个Co原子和一个氧空位共同形成一个活性Co空位对,通过改变反应路径协同促进水分解.氧空位不仅作为活性位点直接参与催化过程,还能有效调节电子密度,提高催化剂的导电性.本工作对于指导高性能催化剂的设计和深入了解催化机理具有重要意义.

Developing bifunctional electrocatalysts with high performance that are easily available,low-cost,and longterm stable is challenging.Interface engineering and vacancy engineering are two effective methods for constructing excellent catalysts.Based on the integration of these two strategies,a heterostructured catalyst with abundant oxygen vacancies was built via electrodeposition.The as-prepared catalyst,V_O-Co(OH)_(2)/CoN,had long-term stability in alkaline electrolyte and demonstrated excellent bifunctional activity with low overpotentials of 52 mV for the hydrogen evolution reaction and 206 mV for the oxygen evolution reaction at 10 mA cm^(-2).The electrolytic cell constructed by V_O-Co(OH)_(2)/CoN only required a cell potential of 1.518 V at 10 mA cm^(-2).According to both the results of experiments and density functional theory computations,the outstanding bifunctional activity of V_O-Co(OH)_(2)/CoN is attributed to the synergistic effect of heterointerface and oxygen vacancies.A Co atom and an oxygen vacancy formed an active Co-vacancy pair near the heterointerface,which synergistically boosted water splitting by changing the reaction path.Oxygen vacancy not only participated in catalysis as an active site,but also effectively adjusted the electron densities to improve the catalyst conductivity.Our work is vital to guide the design of highperformance catalysts and understand the catalytic mechanism.