Multi-functional O2–H2 electrochemistry by an abundant mineral: a novel and sustainable alternative for noble metals in electrolyzers and metal–air batteries

Abstract

Developing sustainable and efficient electrocatalysts for clean energy-based technologies would hasten the commercialization of high-power devices such as metal–air batteries, electrolyzers, and fuel cells. With immense potential to root out the increasingly startling carbon emission, a disruptive invention with an alternate catalyst of abundance and comparable performance as that of the existing benchmarked noble metal catalysts is awaited. Herein, we report the identification of such a novel biomineral-based catalytic composite with exceptionally durable hydrogen and oxygen electrochemistry. Hydroxyapatite on reduced graphene oxide (HAG), though metal-free, surpasses the best-known noble metal catalysts in the OER–HER and OER–ORR bifunctional performances. Its high abundance and elevated methanol tolerance compared to the benchmark catalysts make HAG an industry favorite as well.