Boosting Electrocatalytic HER Activity of 3D Interconnected CoSP via Metal Doping: Active and Stable Electrocatalysts for pH-Universal Hydrogen Generation

Recently, many research studies have been focused on anion or cation substitution into the lattice of pyrite-type cobalt disulfide (CoS2) for enhancing the hydrogen evolution reaction (HER) performance. Nonetheless, finding the correct pair of anion–cation dual substitution with added synergistic effect for boosting pH-universal HER activity remains an ongoing challenge. Additionally, a generalized activity descriptor and the HER mechanism in alkaline media remain elusive. Herein, to elucidate the HER mechanism and obtain the suitable anion–cation pair, we investigated the codoping of metal cations (Ti/V/Cr/Mn/Fe) and phosphorus anions into the CoS2 moiety. Our theoretical prediction revealed that Ti and P codoping into CoS2 exhibits superior HER performance at both pH 0 and 14, which is ascribed to the weak hydrogen binding energy in acid and fast water dissociation kinetics in alkaline media, thereby promoting HER. Remarkably, a follow-up experiment confirmed that Ti-CoSP showed astonishing HER activity inducing low overpotentials of 44 and 132 mV at −10 mA cm–2 in acidic and alkaline media, respectively, with superior stability for 40 h.