A grinding approach for the formation of mesoporous metal oxide with superior electrocatalytic performance

Developing electrocatalysts with superior activity, high stability, and low cost is in high demand for oxygen evolution reactions. Many approaches have been established to prepare metal oxide structures with high electrocatalytic performance. However, there is still a massive room for improving the efficiency and lowering the cost of the process, especially considering the necessity to scale-up to industrial scales. For example, most of the common methods suffer from: 1) low quantity of the catalyst, 2) the synthetic process is complicated to scale-up, 3) most of the catalysts undergo an activation (conversion) process at a high temperature before the catalytic reaction. This step increases the probability of sintering between particles, resulting in loss of specific surface area. Moreover, the heating damages the conductivity of the supported electrode.

In this work, we use a templating method to increase the production quantity and to activate a cobalt-based metal oxide catalyst before preparing the electrode. After deposition, the template is removed via an acid treatment followed by a grinding process to increase the specific surface area. Finally, the electrode is prepared by mixing the metal oxide with carbon black and a binder material. The as-synthesized Co₃O₄ mesoporous material shows a superior electrocatalytic performance toward oxygen evolution reaction in a basic environment, and a maximal current density of 75 mA cm^–2 at 0.8 V vs. Ag/AgCl and an onset potential of 0.5 V vs. Ag/AgCl. This method was expanded to include other electrocatalysts such as NiO and MnO₂.