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

TLDR: In this article, a series of ternary FeCoNi (FCN•PBAs) were obtained by temperature control surfactant desorption ability and their morphologies changed from truncated octahedrons to cubic octahedral and truncated cubes.

Abstract: 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.