Hierarchical N-Doped Co/Carbon Heterostructures with Tunable Selectivity for H₂O₂ Production from Air

As a green oxidant, H2O2 can be produced via the electrochemical reduction of oxygen. However, current techniques usually require high-pressure air or oxygen gas to accelerate the oxygen diffusion via bubbling in the electrolyte. Here, we design a multifunctional gas capture catalyst (GCC) of hierarchical N-doped Co/carbon heterostructures with a Schottky contact at the interface for the highly efficient capture and selective transformation of oxygen from air to H2O2. Tuning the Schottky contact at the Co/NxC interface boosts H2O2 production in acid media. Remarkably, as the catalyst in the H-cell without an ion-exchange membrane and a polytetrafluoroethylene (PTFE) assistant, the Co/N2.1C GCC could provide an accumulated H2O2 yield of 2413 mg L-1 h(-1) (730 mmol g(-1) h(-1)) at 20 mA cm(-2) in 0.1 M HClO4 solution under natural air diffusion. More importantly, consistent Faradaic efficiencies (75%) at a wide scope of working potentials ranging from -0.54 to 0.46 V vs RHE were attained. The connected hierarchical structure of Co/N2.1C GCC remains stable without an obvious flooding effect confronted by conventional gas flow electrodes. This work affords valuable information for fabricating highly efficient 2e(-) ORR catalysts and expands heterojunction catalysts for H2O2 production.