Electrocatalytic hydrogen peroxide production in acidic media enabled by NiS2 nanosheets

Abstract

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.