Electrocatalytic hydrogen peroxide production in acidic media enabled by NiS2 nanosheets

The selective two-electron O2 reduction reaction (2e− ORR) represents a green, mild, and on-site means of synthesizing H2O2. However, its practical feasibility depends on the development of advanced electrocatalysts, and limited experimental work has been done on non-precious-metal-based materials for the H2O2 electrogeneration in acids. Our study here introduces NiS2 nanosheets for the first time as an efficient electrocatalyst for the 2e− ORR under acidic conditions. In 0.05 M H2SO4, the NiS2 catalyst shows an onset overpotential of ∼130 mV and offers high selectivity (H2O2 percentage up to 99%). Moreover, the NiS2 catalyst attains the largest faradaic efficiency of 98% and the highest H2O2 yield rate of 109 ppm h−1 at 0.456 V and 0.156 V in the H-cell testing, respectively. The catalytic mechanism is revealed by theoretical calculations.