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

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 Ni 3 S 2 (P-doped Ni 3 S 2 ) nanosheets array grown on Ni foam has been successfully synthesized and further applied as the efficient electrocatalysts for HER in alkaline media. P-doped Ni 3 S 2 shows higher catalytic activity for HER compared with pristine Ni 3 S 2 , 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 Ni 3 S 2 , enhance the electrical conductivity, optimize the HER Gibbs free-energy (Δ G H* ) and the change of water adsorption energy (Δ G H2O* ), and reduce the barrier of water dissociation optimize the HER Gibbs free-energy (Δ G H* ), change water adsorption energy (Δ G H2O * ) 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.