In-situ Synthesis of Binder-Free MoS 2 /FeOOH@CC Heterostructure as Photoelectrode for High-Performance Photo-Rechargeable Zinc-Ion Batteries

Abstract

Photorechargeable zinc-ion batteries (PRZIBs) have garnered considerable research interest as a promising alternative to conventional solar charging technologies due to their intrinsic safety, environmental compatibility, and cost-effectiveness. However, the development of photoelectrode materials that simultaneously enable efficient light harvesting and electrochemical energy storage remains a significant challenge. Herein, we report a rationally designed nanostructured electrode fabricated via a two-step hydrothermal method, wherein rod-like FeOOH and petal-like MoS2 are sequentially grown on a flexible carbon cloth substrate. The resulting MoS2/FeOOH@CC heterostructure exhibits dual functionality in photoelectric conversion and energy storage. The heterojunction facilitates the separation of photogenerated electron–hole pairs and provides an efficient pathway for Zn2+ diffusion. When employed as the cathode in a photorechargeable zinc-ion battery, the MoS2/FeOOH@CC photoelectrode delivers a specific capacity of 323.9 mAh g-1 under illumination (100 mW cm-2), compared to 231.6 mAh g-1 in the dark at a current density of 100 mA g-1, corresponding to a 39.8% enhancement. The battery retains approximately 60% of its initial capacity after 300 cycles. Electrochemical analyses reveal that the improved charge–discharge performance under illumination originates primarily from accelerated internal charge transfer induced by light irradiation at the heterojunction, rather than from photothermal effects. Furthermore, the working mechanism of the MoS2/FeOOH@CC photoelectrode is systematically elucidated through ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). This study provides a viable strategy for the design of advanced photoelectrode materials toward high-performance PRZIBs.