Cobalt-based electrocatalysts have been well exploited in oxygen reduction reactions (ORR) for potential applications in alkaline-based fuel cells. In this study, we report a one-pot protocol to prepare facile Co/CoN_x–C electrocatalysts, which are comprised of metallic Co⁰ clusters simultaneously integrated with Co^IIN_x species on N-doped carbon matrixes. The optimized Co/CoN_x–C exhibits high ORR activity in terms of E_onset (0.926 V vs. RHE) and E_1/2 (0.853 V) and shows good stability and methanol tolerance compared with the benchmark Pt/C in an alkaline electrolyte. The enhanced ORR performance arises from the unique integration and synergetic effect of Co clusters with adjacent single-atomic CoN_x sites in the resultant Co/CoN_x–C electrocatalysts, which is further substantiated by density functional theory simulations. This scalable synthesis strategy provides a perspective for design of highly efficient non-noble metal electrocatalysts, encouraging extensive utilization for electrochemical energy conversion.

ZnO-Fe₂O₃ mixed oxides and supported gold nanocatalysts were prepared by using coprecipitation and deposition–precipitation methods, respectively. Cinnamaldehyde hydrogenation over various ZnO-Fe₂O₃ mixed oxides supported gold nanocatalysts have been investigated at 140 °C and a hydrogen pressure of 1.0 MPa. The molar ratio of Fe to Zn was found to greatly affect the selective hydrogenation catalytic activity of ZnO-Fe₂O₃ mixed oxide supported gold nanocatalysts. Among these supported gold nanocatalysts in this work, Au/Zn_0.7Fe_0.3O_x (Au loading of 1.74 wt %) exhibited the highest conversion of cinnamaldehyde and high selectivity to cinnamal alcohol. The excellent catalytic activity of Au/Zn_0.7Fe_0.3O_x was tightly associated with a large surface area, small gold nanoparticles, and good H₂ dissociation ability at low temperature.

The Hm/Cy@C-900 catalyst exhibits a ORR performance (E_1/2 0.845 V vs. RHE), and its equipped zinc–air battery reaches a power density of 192 mW cm⁻²@260.7 mA cm⁻², which is attributed to the promotional effect of FeS_x and Fe₃C clusters with FeN_x sites.