Hydrogen Evolution Enhancement over a Cobalt-Based Schottky Interface

A proof-of-concept strategy for significant enhancement of hydrogen evolution reaction (HER) performance of transition metals via construction of a metal/semiconductor Schottky junction is presented. The decoration of low-cost commercial TiO2 nanoparticles on the surface of microscale Co dendrites causes a significant charge transfer across the Co/TiO2 Schottky interface and enhances the local electron density at the Co surface, confirmed by X-ray photoelectron spectroscopy results and density functional theory calculations. The Co/TiO2 Schottky catalyst displays superior HER activity with a turnover frequency of 0.052 s–1 and an exchange current density of 79 μA cm–2, which are about 4.3 and 4.0 times greater than that of pristine Co, respectively. Moreover, the Co/TiO2 Schottky catalyst displays excellent electrochemical durability for long-term operation in both alkaline solution and high saline solution. Theoretical calculations suggest that the Schottky junction plays an important role to optimize hydrogen adsorption free energy (ΔGH*) by tuning the electronic structure, which enhances the performance for HER of the Co/TiO2 Schottky catalyst. This study of modulating the electronic structure of the catalysts via the Schottky junction could provide valuable insights for designing and synthesizing low-cost, high-performance electrocatalysts.