Fig. 4: DFT calculation.

a Differential charge density at the interface between NiCu and CdS, and the corresponding planar averaged charge density difference. Yellow and blue colours represent an increase and decrease in electron density, respectively. b Possible active sites for the independent adsorption of H atoms. c Free-energy diagrams for hydrogen evolution pathways. Dark blue, pink, light brown, yellow and white balls represent Ni, Cu, Cd, S and H atoms, respectively. Source data are provided as a Source Data file.