Morphology engineering of atomic layer defect-rich CoSe2 nanosheets for highly selective electrosynthesis of hydrogen peroxide

Abstract

Hydrogen peroxide (H₂O₂) is widely used as a green oxidant for varying applications. Electrosynthesis is an economical and environmentally-friendly strategy to directly produce H₂O₂. Its practical production is hindered, however, by the lack of highly efficient and selective as well as low-cost electrocatalysts. Transition metal chalcogenide materials have been proved to be good catalysts for the oxygen evolution reaction, but their selectivity towards conversion of O₂ to H₂O₂ remains unsatisfactory. In this work, 3 atomic-layer defect-rich CoSe₂ nanosheets have been successfully grown on carbon cloth as a high performance electrocatalyst. The morphology of CoSe₂ can be tuned by regulating the wettability of the growth substrate. The atomic-layer CoSe₂ nanosheets showed unprecedented 92% selectivity towards H₂O₂ production in alkaline solutions, and the yields of H₂O₂ in alkaline and acidic solutions were 1227.7 mg L⁻¹ h⁻¹ and 894 mg L⁻¹ h⁻¹, respectively. The high efficiency and selectivity originate from the rich defects in the atomic-layer CoSe₂ nanosheets, which can accelerate the adsorption of OOH by the exposed Co defect sites.