Abstract:

CuO/g-C₃N₄ composites were prepared by solid-state thermal decomposition method.The CuO/g-C₃N₄ composites were characterized by X-ray diffraction（XRD），N₂ adsorption-desorption（BET），ultraviolet-visible diffuse reflectance spectroscopy（UV-vis DRS），X-ray photoelectron spectroscopy（XPS），steady-state fluorescence spectroscopy（PL），transient photocurrent（TPC），electrochemical impedance spectroscopy（EIS），capacitance voltage characteristics（CV） and grain boundary capacitance characteristics（GCD）.It was applied to the degradation of organic dye methylene blue（MB） and supercapacitor electrode materials.After the combination of CuO and g-C₃N₄，the spectral range was significantly broadened，the efficient separation of photogenerated carriers was realized，the interface/surface resistance was reduced，and the charge transfer was more efficient，which was due to the successful construction of heterojunction.When the dosage of CuO/g-C₃N₄ was 25 mg，the initial concentration of MB dye solution was 50 mg/L，the degradation rate of MB was 90.97% after dark adsorption for 60 min and visible light（λ>420 nm） irradiation for 60 min.The degradation rate of MB was still 90.28% after 5 cycles，showing excellent photocatalytic activity and stability.CuO/g-C₃N₄ composite was used as the anode material of supercapacitor.The maximum specific capacitance of CuO/g-C₃N₄ composite was 379.79 F/g at the current intensity of 2 A/g.The capacitance retention rate and Coulomb efficiency of the electrode material were 98.06% and 99.54%，respectively，when the current intensity was 10 A/g and the electrode material was recycled 5 000 times.It was an ideal electrode material for supercapacitors.

Key words: CuO/g-C₃N₄, heterojunction, supercapacitor, photocatalytic degradation, composite materials, methylene blue