Department of Chemistry2024-11-0920202155-543510.1021/acscatal.0c030942-s2.0-85097733251http://dx.doi.org/10.1021/acscatal.0c03094https://hdl.handle.net/20.500.14288/9210Developing active, durable, and inexpensive electrocatalysts is critical for hydrogen production to meet ever-growing sustainable energy needs. Nickel sulfides offer significant potential as electrocatalysts for a hydrogen evolution reaction (HER); however, the active phase governing the electrochemical conversion is still under debate. We show that mesoporous thin-film NiS2 synthesized by a novel soft-templating method without post-sulfurization exhibits superior HER activity in alkaline media after a preconditioning step that results in sulfur leaching, amorphization of the surface, and collapse of the mesoporous structure. A comparative analysis with crystalline NiS2 reveals that partial hydroxylation of the under-coordinated Ni sites is responsible for the superior HER activity.Chemistry, physical and theoreticalJournal Article6088505000647835