Abstract

Hydrogen evolution reaction (HER) has been severely suppressed by the first proton adsorption step, due to the “shackles” of the surrounding water in the form of hydronium ions (H13O6+). Here, it has been found anionic vacancies in NiCo2A4 (A = O, S, Se) can weaken the shackles of surrounding water in H13O6+, resulting into efficient capture of H+ to form a H+-enriched field. Taking selenium vacancy-rich NiCo2Se4 nanowires on nitrogen-doped carbon nanofibers as an example, it displays higher electrocatalytic activities with low overpotential of 168 mV at 10 mA cm−2 and a Tafel slope of 49.8 mV dec−1. The HER performance is strongly related to the anionic vacancy size, the larger the anionic vacancy size is (VSe > VS > VO), the higher the HER activity does. Guided by density functional theory calculations, it is found that the point defect structures can not only strengthen its interfacial linkage force with H+ by weakening the hydration force of contiguous hydronium ion, but also increase its charge density for efficient electron transfer to adsorbed H+. Therefore, this work creates a useful strategy to optimize the HER performance of traditional bimetallic compounds by engineering the solid-liquid-gas three-phase interfacial interaction.