Electron regulation of CeO₂ on CoP multi-shell hetero-junction micro-sphere towards highly efficient water oxidation

CeO₂ has been identified as a significant cocatalyst to enhance the electrocatalytic activity of transition metal phosphides (TMPs). However, the electrocatalytic mechanism by which CeO₂ enhances the catalytic activity of TMP remains unclear. In this study, we have successfully developed a unique CeO₂-CoP-1-4 multishell microsphere heterostructure catalyst through a simple hydrothermal and calcination process. CeO₂-CoP-1-4 exhibits great potential for electrocatalytic oxygen evolution reaction (OER), requiring only an overpotential of 254 mV to achieve a current density of 10 mA cm^-2. Moreover, CeO₂-CoP-1-4 demonstrates excellent operating durability lasting for 55 h. The presence of CeO₂ as a cocatalyst can regulate the microsphere structure of CoP, the resulting multishell microsphere structure can shorten the mass transfer distance, and improve the utilization rate of the active site. Furthermore, in situ Raman and ex situ characterizations, and DFT theoretical calculation results reveal that CeO₂ can effectively regulates the electronic structure of Co species, reduces the reaction free energy of rate-limiting step, thus increase the reaction kinetic. Overall, this study provides experimental and theoretical evidence to better comprehend the mechanism and structure evolution of CeO₂ in enhancing the OER performance of CoP, offering a unique design inspiration for the development of efficient hollow heterojunction electrocatalysts.