In Situ Photodeposition of Au Nanoparticle Plasma: Enhanced Defect-State g-C3N4 Photocatalytic Hydrogen Evolution

To further enhance the hydrogen evolution activity of g-C3N4, Au nanoparticle (NP)-modified defective-state g-C3N4 nanosheet photocatalysts (Au/HCN) were successfully prepared through in situ photodeposition in this study. The prepared Au/HCN exhibited an excellent photocatalytic hydrogen evolution activity. Under full spectrum, the hydrogen production rate of Au/HCN (7289 μmol·g–1·h–1) was 1.6 times higher than that of Au NPs-modified pure g-C3N4 nanosheets (Au/CN) (4437 μmol·g–1·h–1) and 4.3 times higher than that of Au NPs-modified bulk g-C3N4 (Au/BCN) (1664 μmol·g–1·h–1). The photoluminescence and steady-state photovoltage spectra indicate that Au/HCN has the highest ability for photogenerated charge separation and photogenerated electron transfer efficiency. The ultraviolet–visible spectrophotometer (DRS) spectra revealed an additional light absorption peak at 520 nm for Au/HCN. The above results indicate that the defects can effectively inhibit the recombination of photogenerated charges from HCN. In addition, the synergistic interaction between Au NPs and HCN, as well as the surface plasmon resonance effect of Au NPs, promoted photocatalytic hydrogen evolution.