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-C 3 N 4 @NF nanoflower electrode materials were prepared base on the in situ chemical etching strategy. The electrochemical performance indicated that the optimized CZNC 2.18 (cobalt–zinc codoped β-Ni(OH) 2 @g-C 3 N 4 ) electrode material with exceptional stability (103.74% capacitance retention after 5000 cycles at 20 mA/cm 2 ) exhibited an ultrahigh capacitance of 19.10 F/cm 2 at a current density of 10 mA/cm 2 under illumination, compared to 12.8 F/cm 2 under dark conditions, achieving a light gain of 149%. The assembled asymmetric photothermal-assisted supercapacitor device delivers energy densities of 3.55 mWh/cm 2 (1.23 mWh/cm 2 ) at corresponding power densities of 8.39 mW/cm 2 (37.03 mW/cm 2 ) 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 CZNC 2.18 exceptional photoelectrochemical performance, establishing a paradigm for light-responsive energy storage material design.