Engineering Non-precious Trifunctional Cobalt-Based Electrocatalysts for Industrial Water Splitting and Ultra-High-Temperature Flexible Zinc-Air Battery

Abstract

Developing efficient, robust, and cost-effective trifunctional catalysts for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) at high current density and high temperature is crucial for water splitting at industry-level conditions and ultra-high-temperature Zinc-air battery (ZAB). Herein, cobalt nanoparticles well-integrated with nitrogen-doped porous carbon leaves (Co@NPCL) by direct annealing of core-shell bimetallic zeolite imidazolate frameworks is synthesized. Benefiting from the homogeneous distribution of metallic Co nanoparticles, the conductive porous carbon, and the doped N species, the as-fabricated Co@NPCL catalysts exhibit outstanding trifunctional performances with low overpotentials at 10 mA cm⁻² for HER (87 mV) and OER (276 mV), long-lasting lifetime of over 2000 h, and a high half-wave potential of 0.86 V versus RHE for ORR. Meanwhile, the Co@NPCL catalyst can serve as both cathode and anode for water splitting at industrial conduction, and exhibit a stable cell voltage of 1.87 V to deliver a constant catalytic current of 500 mA cm⁻² over 60 h. Moreover, the excellent trifunctional activity of Co@NPCL enables the flexible ZAB to operate efficiently at ultra-high temperature of 70 °C, delivering 162 mW cm⁻² peaks power density and an impressive stability for 4500 min at 2 mA cm⁻².