Microwave-Hydrothermal Synthesis of FeCo-LDH for Photo-Assisted Asymmetric Supercapacitors with Enhanced Energy Storage

Photo-assisted supercapacitors constitute an emerging field focused on harnessing solar energy to augment electrochemical charge storage, with electrode material design playing a pivotal role in driving progress in this area. In this work, FeCo layered double hydroxide was directly grown on nickel foam (FeCo-LDH/NF) via both microwave-assisted and conventional hydrothermal methods for a systematic comparison of their synthesis efficiency, morphology, and photo-assisted capacitive performance. Experimental results demonstrate that the microwave-assisted route is significantly more efficient, requiring only 40 min to achieve a mass loading of ∼1 mg cm -2 , whereas the conventional method necessitates 2 h under otherwise identical conditions. The FeCo-LDH/NF electrode prepared by microwave-assisted synthesis exhibits a uniform hierarchical structure with abundant electroactive sites and delivers a specific capacitance of 1335 F g -1 at 1 A g -1 under illumination, corresponding to a 28.6 % enhancement compared to its performance in the dark (1038 F g -1 ). This improvement is primarily attributed to the promotion of surface redox reactions by photogenerated electron-hole pairs. Notably, the microwave-synthesized FeCo-LDH/NF outperforms its conventionally synthesized counterpart in terms of specific capacitance, rate capability, and photo-induced capacitance enhancement. An asymmetric supercapacitor assembled with the microwave-synthesized FeCo-LDH/NF as the positive electrode and activated carbon (AC) as the negative electrode delivers an energy density of 72.06 Wh kg -1 under illumination at a power density of 2.88 kW kg -1 , significantly higher than that achieved in the dark (60.1 Wh kg -1 ). This study not only offers a rapid and efficient synthesis strategy for high-performance FeCo-LDH electrodes but also provides new insights into the design of photo-assisted energy storage devices.