Photocatalytic dye degradation by synergistically Cu LSPR and Schottky barrier enhanced Cu/g C3N4

The issue of water pollution has emerged as a formidable challenge, prompting a pressing need for solutions. The utilization of metal nanoparticles with surface plasmon resonance and semiconductor composite photocatalysts is regarded as a highly effective approach to solve this problem. gC3N4 is an effective catalyst for the degradation of organic pollutants. Its photocatalytic performance could be enhanced by the use of the metal such as Au, Ag, and Cu. However, the Schottky barrier is generally believed to be the reason that Cu can enhances the photocatalytic performance of gC3N4. In fact, the plasmonic of Cu will also have an effect on the photocatalytic effect of gC3N4, like Au and Ag. In this study, it is first proposed that the photocatalytic performance of gC3N4 can be enhanced by combining the plasmonic of Cu and the Schottky barrier. Cug/C3N4 nanocomposites with stable crystal structure, with Cu as the core and gC3N4 as surface coating, were synthesized and characterized by transmission electron microscopy (TEM), Xray diffractometer (XRD) and ultravioletvisible spectroscopy (UVVis) and Xray photoelectron spectroscopy (XPS). Then, it is optimized that the Cu/gC3N4 composite material which were prepared with 200 nm Cu particles, GSH as the ligand bridge, and a Cu: gC3N4 ratio of 5:1, have the best photocatalytic property, which is 16.7 times of the photocatalytic property of gC3N4. Besides, the transfer efficiency of hot electrons of 33% (from Cu to gC3N4) under the influence of the Schottky barrier (0.58 eV) is calculated theoretically. On this basis, the mechanism of Cu nanoparticles enhancing the photocatalytic performance of gC3N4 was also been proved through the calculation result and transient photocurrent spectroscopy (TPC), electrochemical impedance spectroscopy (EIS), and steadystate transient fluorescence spectroscopy (PL) characterization. The excellent photocatalytic performance of the Cu/gC3N4 composites is due to the simultaneous influence of Schottky barrier and LSPR of Cu.