Potassium-doped-C3N4/Cd0.5Zn0.5S photocatalysts toward the enhancement of photocatalytic activity under visible-light

Abstract

The construction of new semiconductor photocatalysts toward the enhancement of photocatalytic activity under visible-light is crucial for a sustainable and clean future. In this paper, cation doping and heterojunction construction were synergistically used to synthesize g-C3N4 matrix composite with a narrow band gap and low recombination rate of photogenerated electron-hole pairs. Potassium-doped-C3N4 (KCN) was used as the matrix to construct semiconductor heterojunction with Cd0.5Zn0.5S (CZS) by hydrothermal method. The resulting composites were characterized through X-ray diffraction, infrared radiation, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and ultraviolet–visible diffuse reflectance spectroscopy techniques to examine its phase structure, morphological, valance state and optical properties respectively. The photocatalytic performance of the samples evaluated by H2 evolution and degrading the Rhodamine B (RhB) aqueous solution. After 12 h hydrothermal reaction at 140 °C, CZS particles uniformly distributed on the KCN matrix. The photocatalytic hydrogen production rate (HPR) of the sample loaded 24 wt% CZS (KCN/CZS 24 wt%) reaches 1.83 mmol/g·h which is 5.6 times of pristine g-C3N4. The degradation rate constant on RhB of KCN/CZS 24 wt% is (k = 0.041 min−1) 7.9 times higher than g-C3N4. The enhanced photocatalytic activity can be attributed to the well-matched energy level of KCN and CZS as well as the extended light absorption of the composites.