In Situ Crystallization of Active NiOOH/CoOOH Heterostructures with Hydroxide Ion-Adsorption Sites on Velutipes-like CoSe/NiSe-nanorods as Catalysts for Oxygen Evolution and Co-catalysts for Methanol Oxidation

Hydroxide ion (OH–) adsorption process is critical for accelerating the half-reactions of both metal–air batteries and direct methanol fuel cells in alkaline media. This study designs a rational catalyst/cocatalyst by constructing the readily available OH–adsorption sites to boost oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). Cobalt selenide-coated nickel selenide nanorods are in situ grown on nickel foam to obtain CoSe/NiSe-nrs/NF via a one-pot solvothermal synthesis route. CoSe-0.2/NiSe-nrs/NF (Co/Ni molar ratio of 0.26) exhibits an excellent OER activity(an overpotential of 310 mV at 100 mA cm–2 and a Tafel slope of 58.3 mV dec–1). The differently oriented CoSe/NiSe-nrs with a velutipes-like structure and metallic property provide a promising electrical conductivity for charge transfer. In situ X-ray diffraction tests verify the crystallization of active β-NiOOH during OER, and the crystallized NiOOH/CoOOH contributes to the excellent OER cycling stability in alkaline media. Sy...