Alkaline water electrolysis performance of mixed cation metal phosphorous trichalcogenides

Journal article, 2024

A variety of mixed-cation metal phosphorus trichalcogenides (MnNiP2S6, FeCoP2S6, FeNiP2S6, CoNiP2S6, FeCoNiP2S6, and the high-entropy CrMnFeNiCoZnP2S6) are synthesized using chemical vapor transport and tested for water splitting under alkaline conditions. Among the materials synthesized, FeCoP2S6 demonstrates the most promising performance, acting as a catalyst with an overpotential of 409 mV and 325 mV for the hydrogen evolution reaction and oxygen evolution reaction (OER), respectively. To further enhance its catalytic activity, a combination of liquid-phase exfoliation techniques assisted by microwave and sonication is employed to FeCoP2S6 (exf-FeCoP2S6), thereby increasing the surface area and exposing more active sites. Promising results are obtained for the OER, with exf-FeCoP2S6 displaying an overpotential of 271 mV, a value very closely matching the best performances reported in the literature under alkaline conditions. Long-term stability tests show a stable profile over time, corroborated by the XPS analysis and computer modeling, which confirms minimal degradation of the catalyst.