Abstract
Developing Earth-abundant, highly efficient, and anti-corrosion electrocatalysts to boost the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER) for the Zn-air battery (ZAB) and for overall water splitting is imperative. In this study, a novel process starting with Cu(2)O cubes was developed to fabricate hollow Ni(x)Co(1-x)Se nanocages as trifunctional electrocatalysts for the OER, ORR, and HER and a reasonable formation mechanism was proposed. The Ni(0.2)Co(0.8)Se nanocages exhibited higher OER activity than its counterparts with the low overpotential of 280 mV at 10 mA cm(-2). It also outperformed the other samples in the HER test with a low overpotential of 73 mV at 10 mA cm(-2). As an air-cathode of a self-assembled rechargeable ZAB, it exhibited good performance, such as an ultralong cycling lifetime of > 50 h, a high round-trip efficiency of 60.86%, and a high power density of 223.5 mW cm(-2). For the application in self-made all-solid-state ZAB, it also demonstrated excellent performance with a power density of 41.03 mW cm(-2) and an open-circuit voltage of 1.428 V. In addition, Ni(0.2)Co(0.8)Se nanocages had superior performance in a practical overall water splitting, in which only 1.592 V was needed to achieve a current density of 10 mA cm(-2). These results show that hollow Ni(x)Co(1-x)Se nanocages with an optimized Ni-to-Co ratio are a promising cost-effective and high-efficiency electrocatalyst for ZABs and overall water splitting in alkaline solutions.