Enhancing Full Water-Splitting Performance of Transition Metal Bifunctional Electrocatalysts in Alkaline Solutions by Tailoring CeO₂–Transition Metal Oxides–Ni Nanointerfaces

Rational design of highly efficient bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is critical for sustainable energy conversion. Herein, motivated by the high activity of OER catalyst on water dissociation that is the rate-determining step of alkaline HER, a bifunctional catalyst of metallic nickel-decorated transition metal oxide nanosheets vertically grown on ceria film (ceria/Ni-TMO) is synthesized by composition controlling and surface engineering. Because of the idealized electronic structure of the active centers and the abundance of such sites, as well as a synergistic effect between the carbon cloth/ceria film and the in situ formed TMO/Ni nanoparticles, the as-synthesized ceria/Ni-TMO exhibited long-time stability and a low cell voltage of 1.58 V at 10 mA/cm 2 when applied as both the cathode and anode in alkaline solutions. Moreover, it is the first time that pH-independent four-proton-coupled-electron-transfer processes and multiple adsorption–desorption processes were found to occur at the interfaces of ceria/TMO and Ni/TMO in a single catalyst for catalyzing OER and HER, respectively.