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

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 H-2 evolution and degrading the Rhodamine B (RhB) aqueous solution. After 12 h hydrothermal reaction at 140 degrees 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. (C) 2019 Elsevier B.V. All rights reserved.