Octahedral Co3O4 particles with high electrochemical surface area as electrocatalyst for water splitting

The preparation of hydrogen by electrochemical water splitting consists of two processes, i.e., hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). It takes scientists a great deal of effort to design and synthesize electrocatalytic materials with high catalytic properties, low fabrication cost and simple synthesis method. In this paper we report the synthesis of the octahedral Co 3 O 4 particles by a simple hydrothermal method , with the double-layer capacitance (C dl ) 154.85 mF cm −2 , and a lot of {111} high-index facets exposed. The Co 3 O 4 of this structure not only contains oxygen vacancies and hydroxyl groups on the surface, but has a high electrochemical surface area. The synergistic effect of these features makes it a high efficiency catalyst for HER and OER. The bright performance is manifested in that the HER in an alkaline medium requires only 77.9 mV overpotential for a current density of 10 mA cm −2 , and the OER needs 301.2 mV overpotential for a current density of 10 mA cm −2 , while during the electrolytic overall water splitting, it just needs 1.60 V for a current density of 10 mA cm −2 . The durability test also shows good performance of the material both for the HER and OER processes with the tolerating time of Chronoamperometry (j-t) curve test for 20 h. This work not only proves the efficient catalytic performance of this material, but also has the guiding significance for the large volume synthesis of electric catalysts used in industry.