Orbital-Selective Modulation of Spatial pz-s Hybridization for Enhanced Photocatalytic H2 Evolution: Insights From NiSe@ReS2+ x Cocatalyst

Abstract

Regulating the p orbital structure of nonmetal active sites is a potential strategy to optimize hydrogen adsorption. However, existing modification ideas primarily focus on the total energy of the p orbitals, while overlooking the crucial spatial information of the multiple projected p_x, p_y, and p_z orbitals, causing a random and nondirectional orbital modification. Herein, we propose a spatial orbital-selective modulation engineering to realize precise and efficient optimization of H adsorption on a core-shell NiSe@ReS_{2+ x} cocatalyst. Theoretical calculations find that the H adsorption intrinsically originates from the selective hybridization between individual S p_z and H 1s orbitals (p_z-s), which unlocks a most direct approach to optimize H adsorption. Based on this, we demonstrate that H adsorption on S sites is directionally weakened by selectively charging spatial S p_z from NiSe to produce electron-rich p_z ^δ- orbitals. This process increases the projected antibonding-orbital occupancy, weakens the spatial p_z-s hybridization, and lowers the H₂-formation energy barrier of ReS_{2+ x}, ultimately achieving an improved H₂-evolution activity. This work offers spatial orbital-level insights into precisely designing effective catalysts for artificial photosynthesis.

Keywords: cocatalyst; photocatalytic H2 evolution; selective hybridization; spatial orbital modulation.