Two-dimensional ZnO/BlueP van der Waals heterostructure used for visible-light driven water splitting: A first-principles study

Abstract

Solar driven water splitting for hydrogen generation has been considered as an important method for collecting clean energy. Herein, based on first-principles calculations, we propose that ZnO/BlueP van der Waals heterostructure can realize overall water splitting reaction for hydrogen generation. Strikingly, the band-gap of 1.83 eV is appropriate, and band alignments straddle the water redox potentials, ensuring the occurrence of hydrogenevolutionreaction and oxygen evolution reaction. Charge density distribution and carrier mobility exhibit significant charge separation and transfer. Visible-light response is improved compared with those of the isolated monolayers. Moreover, hydrogenevolutionreaction is actually realized on the ZnO layer, while oxygen evolution reaction is implemented on the BlueP layer. Through the investigation of the adsorption and dissociation reactions of H2O, we observe that two neighboring H*s prefer to combine to form H2 by overcoming a lowered energy barrier of 0.75 eV. Strain effect indicates that the lateral compressive strain of −4% to 0% and the vertical tensile strain of 0% to +6% can effectively tune band-gap and band alignments. The results indicate that ZnO/BlueP vdW heterostructure is probable highly efficient photoelectric material used for visible-light driven water splitting for hydrogen generation.