N and Mn dual-doped cactus-like cobalt oxide nanoarchitecture derived from cobalt carbonate hydroxide as efficient...

Collaborative design in both nanoarchitecture and electronic structure is of great significance for cost-effective electrocatalysts towards oxygen evolution reaction (OER). Herein, cactus-like porous cobalt oxide (Co₃O₄) nanoarchitecture doped with manganese cation and nitrogen anion (N-Mn-Co₃O₄) was fabricated on the nickel foam by hydrothermal and subsequent N₂ plasma treatment. Unique hierarchical structure and surface atomic engineering endow the N-Mn-Co₃O₄ with rich active sites, abundant oxygen vacancies, enhanced electrical conductivity and rapid ion diffusion. Hence, as electrocatalysts for OER, the N-Mn-Co₃O₄ exhibits low overpotentials of 302 and 320 mV to drive the current density of 50 and 100 mA cm^-2, respectively, and superior stability over 40 h under alkaline environments. More strikingly, when assembling the N-Mn-Co₃O₄ with Pt/C anode into an alkaline electrolyzer, the system delivers a small voltage of 1.55 V at the current density of 10 mA cm^-2 with excellent durability. This work may shed light on design and fabrication of efficient OER electrocatalysts by synergistically tailoring electronic and geometric structures.