Size engineering of porous CuWO4-CuO heterojunction for enhanced hydrogen evolution in alkaline media

Constructing electrocatalysts with heterogeneous interfaces is of great significance for improving the performance of electrocatalytic hydrogen production. In this work, CuWO4 center dot 2H(2)O-CuO (P-CWOC) was synthesized by hydrothermal method, and spherical porous CuWO4-CuO (CWOC) was obtained through annealing treatment. The size of CuWO4-CuO can be controlled from 72 to 221 nm by regulating the supersaturation of the solution. Among them, CuWO4-CuO with a particle size of 72 nm (CWOC-72) possesses the most oxygen vacancies and the largest specific surface area. The W atom in the heterostructure of CuWO4 and CuO can affect the electronic structure of Cu atoms, and the presence of oxygen vacancies is beneficial for increasing the surface oxygen affinity of the composite material. Benefitting from the largest number of oxygen vacancies and the largest specific surface area, the CWOC-72 own the best catalytic performance compared to the other four catalysts. The overpotential at a current density of 10 mA cm(-2) is 121 mV, and the Tafel slope is 70 mV.dec(-1). Its excellent stability was confirmed by chronoamperometry, in-situ XRD, and in-situ Raman spectroscopy, and its alkaline HER performance is superior to most CuO-based catalysts.