N and Mn dual-doped cactus-like cobalt oxide nanoarchitecture derived from cobalt carbonate hydroxide as efficient electrocatalysts for oxygen evolution reactions.

ABSTRACT

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.