Nature‐Inspired Synthesis of Nanostructured Electrocatalysts through Mineralization of Calcium Carbonate

Abstract Biomineralization is a biogenic process that produces elaborate inorganic and organic hybrid materials in nature. Inspired by the natural process, this study explored a new mineralization approach to create nanostructured CaCO 3 films composed of amorphous CaCO 3 hemispheres by using catechol‐rich polydopamine (PDA) as a biomimetic mediator. The thus synthesized biomimetic CaCO 3 was successfully transformed to nanostructured films of metal‐oxide minerals, such as FeOOH, CoCO 3 , NiCO 3 , and MnOOH, through a simple procedure. The CaCO 3 ‐templated metal‐oxide minerals functioned as efficient electrocatalysts; a CaCO 3 ‐templated cobalt phosphate (nanoCoPi) film exhibited high stability as a water‐oxidation electrocatalyst with a current density of 1.5 mA cm −2 . The nanostructure of nanoCoPi, consisting of individual nanoparticles (≈70 nm) and numerous internal pores (BET surface area: 3.17 m 2 g −1 ), facilitated an additional charge‐transfer pathway from the electrode to individual active sites of the catalyst. This work demonstrates a plausible strategy for facile and green synthesis of nanostructured electrocatalysts through biomimetic CaCO 3 mineralization.