Improved atomic hydrogen desorption by Cu3N with suitable electronic structure to enhance photocatalytic H2 evolution

Abstract

Photocatalytic hydrogen evolution reaction (HER) using solar energy as a driving force is considered to be one of the most promising approaches to alleviate energy and environmental problems. However, the problem of low solar conversion efficiency resulted from the easy recombination of photogenerated electron-hole pairs in semiconductor catalysts needs to be solved urgently. Theoretical calculations were firstly taken to prove that copper nitride (Cu3N) exhibits a matched D-band center position and hydrogen adsorption Gibbs free energy (ΔGH∗), which can improve the H2 adsorption/desorption balance and then achieve an effective promotion of photogenerated charge kinetics. Cu3N was herein chosen as a co-catalyst to enhance photocatalytic HER performance. Two-dimensional carbon nitride (2D CN) was chosen as the catalyst due to the layer structure which could shorten electronic transmission distance. The results showed that the HER activity of Cu3N/2D CN is 117 times higher than that of 2D CN (2721.55 vs. 23.18 μmol/g/h) and an apparent quantum yield of 3.78% at 420 nm. Compared with other Cu(I)-based composite catalysts, Cu3N/2D CN also exhibits the highest HER activity. This work investigates the transfer process of photogenerated carriers and reveals the photocatalytic mechanism through a combination of theoretical calculations and experimental characterization.