Morphology and Composition Regulation of FeCoNi Prussian Blue Analogues to Advance in the Catalytic Performances of the Derivative Ternary Transition-Metal Phosphides for OER

Prussian blue analogues (PBAs) are mostly binary metallic compounds with a cubic structure, which greatly limits the structure and component of derived transition-metal phosphides (TMPs) and affects their catalytic activities. This work focuses on regulating the morphology and composition of the PBA at the front-end to optimize the OER performance of the derived TMP. By temperature control surfactant desorption ability, we obtain a series of ternary FeCoNi (FCN-PBAs). With the increase of temperature, their morphologies change from truncated octahedrons to cubic octahedrons and truncated cubes, in which the Fe content basically remains unchanged and the Co/Ni ratio gradually decreased. Due to the synergistic effect among ternary TMPs, all phosphidation products (FCN-P) exhibit better OER activities than RuO2, among which FCN-40-P shows the best performance. As confirmed by XPS analyses, the appropriate chemical composition enhances the oxidizabilityof TM species, promotes the chemical adsorption of OH-, and accelerates OER kinetics.