Amorphous Iron(III)-Borate Nanolattices as Multifunctional Electrodes for Self-Driven Overall Water Splitting and Rechargeable Zinc–Air Battery

Highly stable and low-cost electrocatalysts with multi-electrocatalytic activities are in high demand for developing advanced energy conversion devices. Herein, a unique trifunctional amorphous iron-borate electrode is developed, which is capable of boosting hydrogen evolution, oxygen evolution, and oxygen reduction reactions simultaneously. The amorphous iron borate can self-assemble into well-defined nanolattices on electrode surface through a facile hydrothermal process, which possess more active sites and charge transfer pathways. As a result, the asymmetry overall water-splitting cell that adopts the amorphous electrodes as anode and cathode can be driven at 1.56 V with the current density of 10 mA cm⁻², which is lowest in state-of-the-art catalysts. Moreover, the water-splitting devices can be powered by a two-series-connected amorphous electrode–based zinc–air battery with high stability and Faradic efficiency (96.3%). The result can offer a potential and promising alternative way to develop metal-borate electrode for multifunctional applications.