Novel g-C3N4/Cu-doped ZrO2 hybrid heterostructures for efficient photocatalytic Cr(VI) photoreduction and electrochemical energy storage applications

Pure ZrO2, graphitic carbon nitride, Cu-doped ZrO2 nanoparticles (Cu-Zr), and doped Cu-Zr nanoparticles decorated on the g-C3N4 surface (g-CuZr nanohybrids) were successfully prepared by a hydrothermal technique. Synthesized catalysts were examined by XRD, FE-SEM, TEM, UV-Vis spectroscopy, photoluminescence (PL), and BET surface measurements, respectively. The photocatalytic reduction of Cr(VI) photoreduction as well as energy storage supercapacitor applications were thoroughly investigated. The g-CuZr hybrid photocatalyst out-performed other pristine photocatalysts in terms of light absorption and catalytic Cr(VI) reduction performance under stimulated solar light irradiation. Furthermore, methylene blue (MB) was used as a photosensitizer to further improve the Cr(VI) photoreduction performance. In precise, the heterostructured hybrid catalyst exhibited improved photocatalytic Cr(VI) photoreduction activity (similar to 88.1%) in 5 mg/L MB solution over other catalysts. Moreover, the decoration of Cu-Zr on the surface of g-C3N4 enhanced the absorption ability of light and catalytic Cr(VI) photoreduction performance. The PL, EIS, and transient photocurrent analysis demonstrated that the efficiency of the charge carrier's separation in the nanohybrid catalyst was superior over other catalysts. Furthermore, heterostructured g-CuZr nanohybrid electrode exhibited superior specific capacitance (297.2 F/g) over other electrodes, which are 5.5 folds (54.01 F/g), similar to 2 folds (144.01 F/g) better than pure ZrO2 and g-C3N4 electrodes. Likewise, the nanohybrid electrode retained about 90% of the capacitive value after 2500 cycles over its initial capacitance.

Automated summary

The study successfully prepared a g-CuZr hybrid photocatalyst with superior light absorption and catalytic performance in reducing Cr(VI) compared to other pristine photocatalysts. In a 5 mg/L MB solution, the hybrid catalyst exhibited improved photocatalytic activity in reducing Cr(VI) (approximately 88.1%) compared to other catalysts.