Snowflake Co3O4-CuO heteroanode arrays supported on three-dimensional framework for enhanced oxygen evolution

Electrochemical oxygen evolution reaction plays a pivotal role in various clean energy conversion and storage systems for producing alternative energy sources. In this work, we have successfully synthesized a novel heterostructure material of snowflake-like Co3O4 nanomaterials attaching on the tip of CuO nanorod arrays supported on three-dimensional copper foam via facile and effective approach. The obtained Co3O4-CuO NRs/CF has been used as efficient electrocatalyst for accelerating the oxygen evolution reaction in alkaline condition, in which a very low overpotential of 340 mV, which was even lower than that of the benchmark RuO2 catalyst, was required to achieve a current density of 20 mA cm(-2), together with a small Tafel slope value of 73.3 mV dec-1. The unique heterostructure and excellent mesoporous characteristic of the Co3O4-CuO NRs/CF materials were the main reasons for its large electrochemical active surface area. Furthermore, the Co3O4-CuO NRs/CF exhibited a much higher electrocatalytic activity than those of the CuO NRs/CF (384 mV at 20 mA cm(-2), 139.6 mV dec(-1)) and Co3O4/CF (360 mVat 20 mA cm(-2), 95.3 mV dec(-1)), as its courterparts. This deomstrated that formation of hetorostructure between snowflake Co3O4 and CuO NRs resulting in enhancing OER performance. In addition to excellent catalytic activity, this catalyst also showed remarkable stability toward the oxygen evolution reaction for at least 30 h under constant potential of 1.6 V in the alkaline condition. The highly catalytic performance for the OER reaction was ascribed to the merits of a unique heterostructure, 3D nanoarrays feature and the synergistic effect between Co3O4 and CuO.