Ultrathin porous Co3O4 nanoplates as highly efficient oxygen evolution catalysts

Abstract

Oxygen evolution reaction (OER) catalysts are of central importance for electrocatalytic/photocatalytic water oxidation and fuel generation. Here we report a new type of ultrathin porous Co₃O₄ nanoplate as a highly efficient OER catalyst. The porous Co₃O₄ nanoplates annealed at 250 °C can be readily synthesized in large quantities with a large surface area of 160.9 m² g⁻¹, a very small crystalline size of ∼3.0 nm, and a thin thickness of ∼10 nm. The large surface area provides more surface active sites for the OER. The structural features of the porous nanoplates significantly enrich the amount of surface abundant catalytic sites, provide more active edge and corner cobalt species with low coordination numbers, and subsequently enhance their OER activity. Meanwhile, the thin thickness facilitates efficient diffusion of chemicals and the escape of the generated O₂ within the electrode. Taken all together, the porous Co₃O₄ nanoplates annealed at 250 °C deliver a high OER activity with an overpotential as low as 258 mV at 1 mA cm⁻², a turnover frequency of 0.0042 s⁻¹ (low bound), a Tafel slope of 71 mV dec⁻¹ in 1.0 M KOH solution and an excellent electrochemical stability.