Ru-exsolved RCO-NVG heterojunction via plasma synthesis: An integrated bifunctional cathode for high-performance flexible zinc-air batteries

Abstract

Zinc-air batteries (ZABs) are promising candidates for flexible electronics due to their high energy density and low cost. However, their development is hindered by the sluggish kinetics of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Herein, we present a novel heterostructured electrocatalyst composed of vertically aligned N-doped graphene (NVG) arrays anchored on Ru-doped ceria (RCO) nanofibers, synthesized via a one-step plasma-enhanced chemical vapor deposition process. Notably, during the plasma-enhanced driven NVG growth, Ru nanoparticles are spontaneously in-situ exsolved from the RCO lattice, forming a unique Ru@RCO-NVG heterostructure. Density functional theory calculations reveal that the Ru@RCO-NVG heterojunction induces interfacial electronic redistribution, thereby significantly lowering the energy barriers for both OER and ORR. Benefiting from the synergistic effects, the Ru@RCO-NVG catalyst exhibits exceptional intrinsic activity towards OER/ORR (an overpotential of 370 mV for OER at 10 mA cm⁻² and a half-wave potential of 0.86 V for ORR), and higher all-solid-state flexible ZAB performance (peak power density of 286.1 mW cm⁻²), surpassing commercial Pt/C-IrO₂ catalysts. This work not only advances the integration of synergistic graphene/ceria composites but also offers a promising strategy for designing efficient electrocatalysts for next-generation energy conversion technologies.