Mn(OH)₂-Decorated 3D Architectures Built from Nickel Carbonate Hydroxide Nanostructured Spheres as Oxygen Evolution Reaction Catalysts

The primary challenge in utilizing Ru/Ir-based materials as oxygen evolution reaction (OER) catalysts is their high cost and insufficient durability. Finding cheap and robust materials to replace them has become a current research trend. Herein, a one-step hydrothermal method was applied to synthesize 3D structured nanospheres of Mn(OH) 2 -modified nickel–hydrogen carbonate oxides (N x M 10–x CH) by using a nickel foam (NF) conductive substrate. Microstructure and surface state measurements showed that the presence of polyvalent Mn increased the oxygen vacancy and lamella of NMCH, which played an important role in activity site and durability enhancement. The electrochemical results show that OER activity and durability of NMCH are heavily dependent on the Mn content, which not only optimizes the initial electronic structure, obtaining an OER overpotential of 282 mV to drive 10 mA cm –2, but also stabilizes the microstructure, obtaining a long-term OER operation of 40 000 s with just 6.63% activity loss. More importantly, the graded potential measurements show that the presence of Mn is beneficial to enhance the durability of NMCH on a high loading potential, which is 1.5 times higher than that of NiMn-LDH. According to the results of our research and testing, NMCH would be a potential option for the OER.