As a clean and renewable energy carrier, hydrogen (H₂) has become an attractive alternative to dwindling fossil fuels.

Zinc–air batteries (ZABs) have several advantages, including high energy density, cheap price and stable performances with good application prospects in the field of power batteries. The charging and discharging reactions for the air cathode of ZABs are the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively, which play an important role in the whole performance of ZAB. Due to the cost and limited reserves of highly active precious metal catalysts, it is crucial to design alternative efficient and stable dual-functional non-precious metal catalysts. In the present review, we present a systematic summary of the recent progress in the use of transition metal-based electrocatalysts as alternatives to precious metals for the positive poles of ZAB air. Combined with state-of-the-art in situ characterization technologies, a deep understanding of the catalytic mechanism of OER/ORR provided unique insights into the precise design of excellent synthetic non-precious metal catalysts from the perspective of atomic structure. This review further shows that the hybrid electric battery is a new strategy to improve the efficiency of the hybrid electric battery, which could be available to alleviate the problem of resource shortage. Finally, the challenges and research trends for the future development of ZABs were clearly proposed.

Electrocatalytic water splitting is one of the most efficient ways of producing green hydrogen energy. The design of stable, active, and efficient electrocatalysts plays a crucial role in water splitting for achieving efficient energy conversion from electrical to hydrogen energy, aimed at solving the lingering energy crisis. In this work, CNT composites modified with CoP-V₄P₃ composites (CoVO-10-CNT-450P) were formed by carbonising a pencil-like precursor (Co₃V₂O₈-H₂O) and growing carbon nanotubes in situ, followed by in situ phosphorylation on the carbon nanotubes. In the HER electrocatalytic process, an overpotential of only 124 mV was exhibited at a current density of 10 mA cm⁻². In addition, as an OER catalyst, a low overpotential of 280 mV was attained at a current density of 10 mA cm⁻². Moreover, there was no noticeable change in the performance of the catalyst over a 90 h test in a continuous total water splitting experiment. The unique electronic structure and hollow carbon nanotube structure of CoVO-10-CNT-450P effectively increased the catalytic active sites, while also significantly improving the electrocatalytic activity. This work provides theoretical guidance for the design and synthetic route of high-performance non-precious metal electrocatalysts, and actively promotes the commercial application of electrochemical water splitting.