The g-C₃N₄ porous nanosheets with different loading amount of Ag nanoparticles (NPs) are successfully prepared by a simple liquid-phase reduction method. These Ag/g-C₃N₄ composites have an improved photocatalytic performance for decomposing organic pollutants compared with that of pure g-C₃N₄ nanosheets. Many measurements have been used for characterizing the samples, such as XRD, FTIR, UV-Vis DRS, PL, XPS, EDS, SEM, and TEM. In Ag/g-C₃N₄, the Ag NPs are uniformly coated on the g-C₃N₄ surface, the diameter is mainly in the range of 8~18 nanometers. Loading of Ag NPs expand the response to the visible light for g-C₃N₄ and increasing the producing rate of photogenerated e⁻-h⁺ pairs. The loading of silver NPs obviously enhances the photocatalytic activity of C₃N₄ nanosheets toward the Rhodamine B (RhB) decomposition under the simulated sunlight irradiation. With different loading amounts of Ag NPs, Ag/g-C₃N₄ (3 wt% of Ag) showed the highest photocatalytic activity for RhB decomposition among these as-prepared samples, which is 10 times of the rate of pure C₃N₄. Based on the experimental results, a possible photocatalytic mechanism for Ag/g-C₃N₄ is proposed.

Energy crises and environmental pollution are two serious threats to modern society. To overcome these problems, graphitic carbon nitride (g-C₃N₄) nanosheets were fabricated and functionalized with SnO₂ nanoparticles to produce H₂ from water splitting and degrade 2-chlorophenol under visible light irradiation. The fabricated samples showed enhanced photocatalytic activities for both H₂ evolution and pollutant degradation as compared to bare g-C₃N₄ and SnO₂. These enhanced photoactivities are attributed to the fast charge separation as the excited electrons transfer from g-C₃N₄ to the conduction band of SnO₂. This enhanced charge separation has been confirmed by the photoluminescence spectra, steady state surface photovoltage spectroscopic measurement, and formed hydroxyl radicals. It is believed that this work will provide a feasible route to synthesize photocatalysts for improved energy production and environmental purification.

This work incorporates a variety of conjugated donor-acceptor (DA) co-monomers such as 2,6-diaminopurine (DP) into the structure of a polymeric carbon nitride (PCN) backbone using a unique nanostructure co-polymerization strategy and examines its photocatalytic activity performance in the field of photocatalytic CO₂ reduction to CO and H₂ under visible light irradiation. The as-synthesized samples were successfully analyzed using different characterization methods to explain their electronic and optical properties, crystal phase, microstructure, and their morphology that influenced the performance due to the interactions between the PCN and the DPco-monomer. Based on the density functional theory (DFT) calculation result, pure PCN and CNU-DP_15.0 trimers (interpreted as incorporation of the co-monomer at two different positions) were extensively evaluated and exhibited remarkable structural optimization without the inclusion of any symmetry constraints (the non-modified sample derived from urea, named as CNU), and their optical and electronic properties were also manipulated to control occupation of their respective highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Also, co-polymerization of the donor–acceptor 2,6-diamino-purine co-monomer with PCN influenced the chemical affinities, polarities, and acid–base functions of the PCN, remarkably enhancing the photocatalytic activity for the production of CO and H₂ from CO₂ by 15.02-fold compared than that of the parental CNU, while also improving the selectivity.

Graphite carbon nitride (g-C₃N₄), as a polymer semiconductor photocatalyst, is widely used in the treatment of photocatalytic environmental pollution. In this work, a Z-scheme g-C₃N₄/Ag/AgBr heterojunction photocatalyst was prepared based on the preparation of a g-C₃N₄-based heterojunction via in-situ loading through photoreduction method. The g-C₃N₄/Ag/AgBr composite showed an excellent photocatalytic performance in the degradation of tetracycline hydrochloride pollutants. Among the prepared samples, g-C₃N₄/Ag/AgBr-8% showed the best photocatalytic ability for the degradation of tetracycline hydrochloride, whose photocatalytic degradation kinetic constant was 0.02764 min⁻¹, which was 9.8 times that of g-C₃N₄, 2.4 times that of AgBr, and 1.9 times that of Ag/AgBr. In the photocatalytic process, ^•O^2– and ^•OH are main active oxygen species involved in the degradation of organic pollutants. The photocatalytic mechanism of g-C₃N₄/Ag/AgBr is mainly through the formation of Z-scheme heterojunctions, which not only effectively improves the separation efficiency of photogenerated electron-hole pairs, but also maintains the oxidation and reduction capability of AgBr and g-C₃N₄, respectively.

Ag@ZnO/BiOCl composites were successfully prepared by in situ precipitation and hydrothermal synthesis and used for the photocatalytic degradation of tetracycline hydrochloride antibiotics. An enhanced photodegradation efficiency was detected after loading Ag nanoparticles, which is attributed to the surface plasmon resonance effect. The optimized sample containing 4% Ag showed 80.4% degradation efficiency in 80 min, which is 2.1 and 1.9 times higher than those of ZnO and ZnO/BiOCl, respectively. The major degrading species involved in the photocatalytic process were detected to be super oxide anions and holes. Based on the obtained results, a possible charge transfer and degradation mechanism has been proposed. This study shows that Ag@ZnO/BiOCl catalyst has a good potential for photodegradation of organic pollutants in water.