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 CaCO3 films composed of amorphous CaCO3 hemispheres by using catechol-rich polydopamine (PDA) as a biomimetic mediator. The thus synthesized biomimetic CaCO3 was successfully transformed to nanostructured films of metal-oxide minerals, such as FeOOH, CoCO3, NiCO3, and MnOOH, through a simple procedure. The CaCO3-templated metal-oxide minerals functioned as efficient electrocatalysts; a CaCO3-templated cobalt phosphate (nano-CoPi) film exhibited high stability as a water-oxidation electro-catalyst with a current density of 1.5 mA cm(-2). The nanostructure of nanoCoPi, consisting of individual nanoparticles (approximate to 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 CaCO3 mineralization.