Tailored Self-Supported Co,Ni/MnO2 Nanorods@Hierarchical Carbon Spheres Chains as Advanced Electrocatalysts for Rechargeable Zn-Air battery and Self-Driven Water Splitting

Designing multifunctional electrocatalysts that combine high efficiency, durability, and affordability for energy storage represents a significant challenge. Here, we introduce a novel trifunctional electrocatalyst synthesized by doping self-supported surface electrochemically functionalized carbon sphere chains/MnO2 nanorods with Co or Ni (Func CSCs-2M/Co0.25 (or Ni0.25) MnOx). These electrocatalysts demonstrate exceptional electroactivity for the oxygen evolution reaction, oxygen reduction reaction, and hydrogen evolution reaction, along with durability comparable to that of commercial Pt/C and IrO2 catalysts. Two Zn-air batteries (ZABs) equipped with Func CSCs-2M/Co0.25MnOx cathodes, connected in series, have the capability to power 39 red light-emitting diodes continuously for an impressive duration of 200 h. Moreover, a self-sustaining water splitting system, powered by ZABs, is showcased, utilizing Func CSCs-2M/Co0.25MnOx as the exclusive catalyst. This system sustains a consistent voltage for up to 20 h under an applied current density reaching as high as 30 mA cm–2. This performance rivals that of noble catalyst systems, showcasing its competitive edge. The study emphasizes the cost-effectiveness of materials and the utilization of low-carbon, renewable rechargeable ZAB energy storage systems, combined with water electrolysis. Such integration has the potential to make a substantial impact in addressing long-term energy and environmental challenges, easing the pressure on these critical fronts.