Efficient and stable electrocatalytic performances of nanostructured composite of CuO and Co2P in the full pH range towards hydrogen and oxygen evolution

Abstract

It is highly desirable to explore non-noble metal catalysts with outstanding intrinsic activity and abundant active sites to ensure efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in the full pH range. In this article, we have prepared a nanoflower-shaped composite material of CuO and Co2P (CuO@Co2P) by extending nanowires on foam copper, which effectively increased the contact area while ensuring stability and conductivity. The synergistic effect between CuO and Co2P promotes the reactivity of HER and OER in the full pH range. For example, the CuO@Co2P/NF electrode requires only the overpotentials of 150 and 374 mV for HER to achieve 10 and 100 mA·cm−2 respectively, and 260 and 391 mV for OER current densities of 10 and 100 mA·cm−2, in 1 M KOH medium. And in a neutral electrolyte of 0.5 M Na2SO4, achieve the same current density values as 10 and 100 mA·cm−2, requires the overpotentials of 82 and 213 mV for HER, and 301 and 472 mV for OER, respectively. Furthermore, the HER overpotential of 206.3 mV is needed up to 100 mA·cm−2 in 0.5 M H2SO4 medium for CuO@Co2P/NF electrode. The composite CuO@Co2P has an excellent electrochemical stability, which shows only 7.12%, 4.02% and 5.3% of current density attenuation during HER tested in 0.5 M H2SO4, 0.5 M Na2SO4 and 1 M KOH, respectively, and the rates of change in the OER process in 0.5 M Na2SO4 and 1 M KOH media are 4.79% and 3.46%. This work expands the efficient application of electrocatalysts in the full pH range and avoids the release of toxic gases during phosphating, which is of great significance for the development of transition metal phosphating composite electrocatalysts.