Ni clusters immobilized on oxygen-rich siloxene nanosheets for efficient electrocatalytic oxygen reduction toward H 2 O 2 synthesis.

Hydrogen peroxide (H 2 O 2 ) electrosynthesis via the two-electron oxygen reduction reaction (2e - ORR) represents a green alternative to the energy-intensive anthraquinone process. However, the practical application of this method is limited by the lack of cost-effective and high-performance electrocatalysts. Reported here is a hybrid catalyst composed of nickel (Ni) clusters immobilized onto the surface of two-dimensional siloxene nanosheets (Ni/siloxene), which exhibits excellent efficiency and selectivity in electrocatalytic oxygen reduction to H 2 O 2 in an alkaline medium, demonstrating a standard 2e - pathway with >95% H 2 O 2 selectivity across a wide potential range. Experimental results disclose that the high performance of Ni/siloxene can be traced to a synergy of the Ni clusters and the oxygen-rich surface of siloxene. Density functional theory (DFT) calculations further reveal a weakened interaction between Ni/siloxene and *OOH and the consequently reduced energy barrier for the *OOH protonation toward H 2 O 2 desorption, thus leading to a high 2e - ORR reactivity and selectivity. This work provides a valuable and practical guidance for designing high-performance 2e - ORR electrocatalysts based on the rational engineering of the metal-support interaction.