Boosting zinc-air battery performance through interface-engineered N-C/g-C3N4 photoelectric synergy

The direct integration of solar energy into zinc-air batteries (ZABs) provides a promising strategy for developing sustainable and high-performance energy storage systems. However, designing light-enhanced ZABs with efficient solar-energy utilization remains a significant scientific challenge. To address this challenge, a nitrogen-doped carbon/graphitic carbon nitride (N-C/g-C 3 N 4 ) composite photoelectrocatalyst was fabricated through mechanical ball-milling. Mechanical ball-milling enabled intimate interfacial coupling between N C and g-C 3 N 4 , thereby inducing interfacial electronic redistribution and facilitating charge transfer. Photoelectrochemical characterization, together with VB-XPS analysis, suggests that the N-C/g-C 3 N 4 interface promotes photogenerated electron transfer from g-C 3 N 4 to the conductive N C network while improving the utilization of photogenerated carriers. When used as the air cathode for ZABs, the composite exhibited strong bifunctional catalytic activity under illumination. Specifically, it exhibited an oxygen reduction reaction (ORR) half-wave potential (E 1/2 ) of 0.90 V and an oxygen evolution reaction (OER) overpotential of 501 mV. As a result, the assembled zinc-air battery (ZAB) achieved an open-circuit voltage (OCV) of 1.50 V, a peak power density of 572.9 mW cm −2 , a specific capacity of 720 mAh g −1 , and stable cycling for over 700 h. These results demonstrate the potential of interface-engineered dual‑carbon-based photoelectrocatalysts for high-efficiency solar-assisted metal-air batteries. Compared with N-C-based zinc-air battery (ZAB) and commercial Pt/C-IrO 2 -based ZAB, the light-enhanced N-C/g-C 3 N 4 -based ZAB exhibit improved photogenerated carrier utilization and facilitated interfacial charge transfer under illumination. These advantages lead to a significant performance enhancement, including an open-circuit voltage of 1.50 V, a peak power density of 572.9 mW cm −2 and ultra-stable charge-discharge cycling for over 700 h. Download: Download high-res image (97KB) Download: Download full-size image