Deciphering The Activity of Co-, Fe- Co-Doped NiS supported on Carbon Cloth prepared via a Novel Strategy for Promoted Water Splitting

Water electrolysis via affordable and efficient electrocatalysts under industrial conditions plays a key role in large-scale green hydrogen production. Since the electrocatalysts may undergo undesired in-situ transformations under high current density, the fabrication of single-phase multi-element sulfides with desired composition is crucial and challenging for the development of sulfide catalysts. In this context, we developed a facile and scalable method to construct Fe and Co co-doped NiS supported on carbon cloth (Fe, Co-NiS-CC). A specific compound of metal sulfide was prepared that can be sprayed on the carbon cloth before being pyrolyzed, resulting in a specific phase of NiS directly attached to the substrate. The presence of dopants and the pyrolysis conditions could control the as-formed phase of NiS. The optimized electrode of Fe, Co-NiS-CC exhibits remarkable performance for industrial water splitting (6 M KOH, 70 °C), achieving a current density of 1000 mA cm^–2at a potential of about 1.698 V. The in-situ XAS and Raman measurements and the characterization of the post-electrocatalysts along with the theoretical calculations revealed that the high performance and long-term stability were attributed to the regulation of electronic configuration and the sustained single-phase of doped sulfides, directly grown on carbon cloth. Therefore, high-performance sulfide electrocatalysts can be stabilized by multi-element doping with the formation of polysulfide species that prevent the leaching of the elements and the destruction of the real active catalysts.