van der Waals g-C3N4/BiLuWO6 Heterojunctions from Theoretical Predictions to Photocatalytic Applications

Heterojunction plays an important role in enhancing the photocatalysis performance of materials. In this paper, van der Waals g-C3N4/BiLuWO6 heterojunction forms a Z-scheme energy band configuration through interlayer binding energy, energy band, work function, and charge density difference calculations. Photogenerated electrons transfer from the conduction band (CB) of g-C3N4 to the valence band (VB) of BiLuWO6. Based on theoretical predictions, 13 heterojunctions were synthesized and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Photocurrent response, impedance, Mott–Schottky curve, and free radical tests further confirm the rapid separation of the photogenerated carriers in the n-type g-C3N4/BiLuWO6 heterojunction. Degradation efficiencies of rhodamine B (RhB) and methylene blue (MB) are 93 and 85% under mercury lamp irradiation, respectively. The values are higher than 50 and 64% for g-C3N4 as well as 14 and 8% for BiLuWO6. Except for pollutant degradation, the H2 evolution rate of the heterojunction is 289.08 μmol/g/h using xenon lamp irradiation, which is higher than 161.08 μmol/g/h of g-C3N4 and 13.13 μmol/g/h of BiLuWO6. The decomposition path of RhB and the improved mechanism of H2 production activity are revealed by high-performance liquid chromatography–mass spectrometry (HPLC–MS) and Gibbs free energy analysis.