Special atmosphere annealed Co3O4 porous nanoclusters with oxygen defects and high proportion of Co2+ for oxygen evolution reaction

Co3O4 has been widely investigated as a promising electrocatalyst in the oxygen evolution reaction (OER) due to its mixed valence states of tetrahedral gap (Co2+) and octahedral gap (Co3+). The reasonable control of the Co2+/Co3+ ratio is the principal pathway to improve the electrocatalytic activity of Co3O4. Therefore, we designed a Co3O4 electrocatalyst supported on Ni foam by a two-step method of prehydrothermal method and post-heat treatment in special atmosphere, which not only formed porous nanoclusters, but also acquired oxygen vacancies on the surface of samples with more Co2+. As a result, the electrocatalyst with oxygen vacancies can achieve a current density of 10 mA/cm(2) with a low overpotential of 343 mV and a modest Tafel slope of 79.5 mV/dec for OER in 0.1 M KOH solution. That is because the generation of oxygen vacancies increased the conductivity of the catalyst and created more active sites for OER. This work provide further insight about inducing oxygen vacancies method into the cost-effective and better performance transition metal oxide-based catalysts for electrochemical applications. (C) 2019 Elsevier B.V. All rights reserved.