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

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.