UCoO4/Co3O4 Heterojunction as a Low-Cost and Efficient Electrocatalyst for Oxygen Evolution.

The development of actinide materials has provided new strategies for the utilization of nuclear waste, such as depleted uranium, a mildly radioactive waste in the nuclear power industry, which could be a precious resource for many fields, especially water splitting. The catalytic performance of water splitting is limited by the slow kinetics of the oxygen evolution reaction (OER), and it is extremely challenging to design efficient OER catalysts that are highly stable and inexpensive. Here, we design and describe a series of U5-35%-Co3O4 electrocatalysts, which were synthesized using uranyl nitrate as a precursor via a simple and scalable method. Interestingly, when the U/Co molar ratio was 20%, a UCoO4/Co3O4 heterojunction formed with high catalytic efficiency and excellent long-term electrolytic stability. The UCoO4/Co3O4 heterojunction catalyst shows a lower overpotential (280 mV) at a current density of 10 mA cm-2, and the slope of Tafel is 43.8 mV decade-1 in a 0.1 M KOH alkaline solution. Soft X-ray absorption spectroscopy shows that the cooperative effect of UCoO4 and Co3O4 can improve the electrochemical activity of the material. This study produced an active U/Co-based catalyst for OER, which provides a simple, scalable, low-cost, and highly efficient catalyst for overall water splitting.