Sulfur-modified nickel selenide as an efficient electrocatalyst for the oxygen evolution reaction

Abstract

The sluggish four-electron transfer of the oxygen evolution reaction (OER) limits the performance of water electrolyzers. Hence, OER electrocatalysts based on earth-abundant elements are urgently needed. Heteroatom doping has been an efficient approach to boost the intrinsic OER activity of the active sites by modifying the electronic structure. Here, a simple anion substitution strategy is reported that increases the OER activity of nickel selenides via a one-step hydrothermal treatment of a metal–organic framework precursor. The resulting S-substituted Ni3Se4 nanoparticles display distortion of their crystal lattice. As expected, the sulfur substitution modifies the electronic structure of Ni3Se4 and leads to outstanding electrocatalytic activity. All the S-substituted Ni3Se4 catalysts exhibit higher OER activities than the original Ni3Se4. The optimized catalyst achieves a current density of 10 mA cm−2 at an overpotential of 275 mV with a Tafel slope of 64 mV dec−1 in 1.0 M KOH. In addition to its electrochemical activity, the S-Ni3Se4-2 catalyst also exhibits good stability with only a 7.5% increase in overpotential at 50 mA cm−2 after 100 hours. This work demonstrates one strategy to modify the electronic structure of transition metal compounds by anion regulation.