Synergistically coupled nickel oxide nanoparticles with single-atom nickel catalysts for high-performance wide-temperature adaptable quasi-solid-state zinc–air batteries

Abstract

Single-atom catalysts (SACs) are known for their superior catalytic activity and selectivity. However, most of the reported works are either confined to metal single-atom or SAC/metal nanoparticle composite sites. Considering well-known metal oxide-supported SAC chemistry, supporting metal oxide nanoparticles on a SAC support can regulate the electronic properties of the active sites and boost the catalytic properties. Herein, we report a silica-MOF-templated approach for designing a concave-shaped mesoporous catalyst, decorated with single-atom Ni sites and ultrasmall NiO nanoparticles. This catalyst shows excellent electrochemical water oxidation performance, much superior to that of commercial IrO₂. DFT calculations suggest a synergy between single-atom Ni sites and NiO nanoparticles via augmentation of Ni d-orbitals near the Fermi level, promoting favorable H₂O adsorption at the active sites. Benefitting from the catalyst's bifunctional OER/ORR nature, when it is applied as a cathode for quasi-solid-state Zn–air batteries (ZABs), a high-power density and ultra-long cycle life is achieved, surpassing greatly the state-of-the-art IrO₂ + Pt/C. In addition, a ZAB hydrogel electrolyte is modified using strong polar and H-bond acceptors DMSO and Zn(BF₄)₂, which improve the interfacial stability and thus wide-temperature tolerance (−70 to 70 °C) of the ZABs via favorable H-bond networking. This work provides a strategy for developing new SAC-based catalysts for the advancement of sustainable water electrolysis and quasi-solid-state ZAB technologies.