Facilitated water adsorption and dissociation on Ni/Ni3S2 nanoparticles embedded in porous S-doped carbon nanosheet arrays for enhanced hydrogen evolution

Abstract

Three-dimensional carbon-based catalysts grown on a conductive substrate offer superior electrocatalytic activities toward hydrogen evolution reaction (HER). Herein, a novel method is described for in situ fabrication of hybrid Ni/Ni3S2 nanoparticles embedded in S-doped carbon nanosheet arrays (Ni/Ni3S2/SC NSAs) on carbon cloth. With the morphological merits of large surface area and high conductivity, Ni/Ni3S2/SC NSAs are demonstrated as an efficient and durable HER catalyst that requires merely 90 mV at a current density of 10 mA cm−2 with a small Tafel slope of 81 mV dec−1. This excellent performance is ascribed to the excellent H2O adsorption property of S-doped C layer and formation of Niδ+ and Sδ− species that promote the cleavage of H–OH bonds. First-principles calculations further reveal that the Ni surface near the Ni/Ni3S2 interface has a larger water adsorption energy (Ead) and lower activation energy for water dissociation (Ea) than pure Ni and Ni3S2, which contribute to enhanced HER performance. This work offers valuable insights into the designing of interface between transition metal-based catalysts and heteroatom-doped carbon materials.