Co–Zn Codoped β-Ni(OH)₂@g-C₃N₄ Electrode with Exceptional Photothermal-Driven Pseudo-Capacitance Improvement

Design of the photosensitive electrode material provides an effective strategy to improve the capacity and stability of supercapacitors. In this study, the photothermal-driven cobalt–zinc-doped Ni(OH)2/g-C3N4@NF nanoflower electrode materials were prepared base on the in situ chemical etching strategy. The electrochemical performance indicated that the optimized CZNC2.18 (cobalt–zinc codoped β-Ni(OH)2@g-C3N4) electrode material with exceptional stability (103.74% capacitance retention after 5000 cycles at 20 mA/cm2) exhibited an ultrahigh capacitance of 19.10 F/cm2 at a current density of 10 mA/cm2 under illumination, compared to 12.8 F/cm2 under dark conditions, achieving a light gain of 149%. The assembled asymmetric photothermal-assisted supercapacitor device delivers energy densities of 3.55 mWh/cm2 (1.23 mWh/cm2) at corresponding power densities of 8.39 mW/cm2 (37.03 mW/cm2) under illumination, surpassing performance metrics observed under dark conditions. The synergistic effects of photogenerated carriers (holes oxidizing Ni(OH)2 to NiOOH and electrons enhancing conductivity), Zn/Co codoping-induced conductivity improvement, and photothermal-assisted ion transport collectively enable CZNC2.18 exceptional photoelectrochemical performance, establishing a paradigm for light-responsive energy storage material design.