Accelerating water dissociation kinetics on Ni3S2 nanosheets by P-induced electronic modulation

Abstract Developing efficient and low-cost electrocatalysts for hydrogen evolution reaction (HER) is important in clean energy systems. Non-noble transition metals are the most promising candidates for the replacement of conventional Pt group catalysts of HER. However, most non-noble metals show poor HER activity due to the intrinsic electronic structures. Herein, P atoms doped Ni3S2 (P-doped Ni3S2) nanosheets array grown on Ni foam has been successfully synthesized and further applied as the efficient electrocatalysts for HER in alkaline media. P-doped Ni3S2 shows higher catalytic activity for HER compared with pristine Ni3S2, which affords the current densities of 10 mA cm−2 at an overpotential of 139 mV and long-term stability over 110 h. Density functional theory (DFT) calculations reveal that the introduction of P atoms modify the electronic structure of Ni3S2, enhance the electrical conductivity, optimize the HER Gibbs free-energy (ΔGH*) and the change of water adsorption energy (ΔGH2O*), and reduce the barrier of water dissociation optimize the HER Gibbs free-energy (ΔGH*), change water adsorption energy (ΔGH2O*) and reduce the barrier of water dissociation. Remarkably, energy integral of a crystal orbital Hamilton population (ICOHP) gives access to the contribution of an atom or a chemical bond to the distribution of one-particle bonding within the transistion state of water dissociation and reveals the reduced essence of water dissociation barrier.