CdS is widely used in photocatalytic research due to its unique photoelectrochemical properties. CdS recombination with narrow bandgap semiconductors and organic compounds plays an important role in photocatalyst exploration. In this study, a cucurbit[6]uril (Q[6]) composite and Ag₂S-doped cadmium sulfide photocatalyst (Q[6]/CdS-Ag₂S) were prepared by chemical precipitation method and their composite was characterized by different methods. The experiment is designed to use visible light as the light source and Rhodamine B as the simulated pollutant. Meanwhile, the effects of Q[6] on the photocatalytic performance of CdSAg₂S were investigated. The results showed that the morphology of Q[6]/CdS-Ag₂S composite after cucurbit[6]uril recombination was similar to cauliflower, while the particle size become smaller. Catalytic performance of the composite catalyst Q[6]/CdS-Ag₂S was significantly higher than that of CdS-Ag₂S, the photocatalytic reaction lasts 110 min, showing the catalytic degradation effciency of 92.4% using 15 mg composite catalyst on 100 mL, 6 mg/L Rhodamine B solution.

Ethylene is the main factor of postharvest spoilage of fruits and vegetables. Therefore, how to reduce or remove the ethylene released during the storage of fruits and vegetables is a problem to be solved. In this study, a series of nickel foam supported TiO₂/WO₃ were prepared by Sol-Gel method. The samples were characterized by different methods. The photocatalytic degradation activity of ethylene under ultraviolet light irradiation was investigated. The results show that TiO₂/WO₃ film is successfully supported on the nickel foam, and there formed heterojunction between TiO₂ and WO₃, which efficiently enhanced the separation and transfer rates of photogenerated electron and hole. The narrowed band-gap also leads to a red shift of optical absorbance and high photoactivity. The photocatalytic activity and stability of TiO₂/WO₃ were excellent under UV light irradiation. When the mass percentage of WO₃ is 6% of TiO₂, the photocatalytic ethylene degradation of the TiO₂/WO₃ composite film reaches maximum, and the degradation rate constant is almost 9.8 times as that of TiO₂. The mechanism of photocatalytic degradation of ethylene by TiO₂/WO₃ supported on nickel foam under ultraviolet light irradiation was also discussed.

Photocatalysis technology possesses great potential in the field of oxidation of nitrogen oxides due to the low energy costs and little secondary pollution. Bismuth carbonate (Bi₂O₂CO₃, BOC)/polypyrrole (PPy) was prepared at room temperature to remove NO under visible light irradiation. After being decorated with PPy, the NO removal efficiency of BOC is enhanced from 9.4% to 20.4% while the generation of NO₂ is reduced from 2% to approximately zero, which are attributed to the oxygen vacancy formed at the interface between BOC and PPy via interfacial hydrogen bonding. Photocurrent and electrochemical impedance spectra indicate that oxygen vacancies promote the separation and migration of photo-induced electrons and holes over BOC, hence improve its photocatalytic activity. Furthermore, the presence of oxygen vacancy promotes the formation of more •O₂ ^-, and then improve the NO oxidation activity and safety of BOC together with •OH.

To overcome the limitation of narrow photo-absorption range and high electron-hole recombination rate of pure BiOCl, a nanocomposite of carbon quantum dots (CQDs) and BiOCl with highly efficient photocatalytic activity was fabricated. The photocatalytic decomposition of rhodamine B (RhB) showed that the CQDs/BiOCl nanocomposite displayed superior photocatalytic performance to pure BiOCl, which was about 3.4 times higher than that of the latter. The optimal loading amount of CQDs was 7.1wt%, which could completely decolorize RhB within a short period of only 2 min, while the degradation rate of RhB was only 29.5% by pure BiOCl in the same period. UV-Vis diffuse reflectance spectra (UV-Vis DRS), photoelectrochemical measurement, and radicals trapping experiments were performed to elucidate the possible mechanism for the enhanced photocatalytic activity of the CQDs/BiOCl composite. The results show that CQD can expand the visible light absorption range of BiOCl, which is beneficial for light harvesting and generation of electron-hole pairs. Moreover, CQDs has unique up-converted photoluminescence behavior, as well as photo-induced electron transfer ability, which leads to enhanced photocatalytic performance of the CQDs/BiOCl composite.

Development of high efficiency catalyst is the key factor to catalytic combustion of volatile organic compounds (VOCs). Herein, amorphous mesoporous phosphated TiO₂ (ATO-P) with high specific surface area supported platinum catalyst was successfully fabricated. P-dopant can increase the surface area (up to 278.9 m²·g^-1) of ATO-P, which is 21 times higher than that of pristine TiO₂, and make the amorphous titanium oxide structure. The supported Pt catalyst with amorphous mesoporous feature shows impressive performance and excellent thermostability for VOCs oxidation. The Pt/ATO-P catalyst exhibits outstanding catalytic efficiency, the T₅₀ and T₉₀ (temperatures required for achieving conversions of 50% and 90%) are respectively 130 ℃ and 140 ℃, for toluene oxidation under high gas hourly space velocity (GHSV) of 36000 mL·h^-1·g^-1 and toluene concentration of 10000 mL·m^-3. The performance is superior to the reference Pt/TiO₂ and comparable with the state-of-the-art catalysts. These findings can make a significant contribution on the new applications of amorphous mesoporous phosphated materials in VOCs removal.

Persistent organic pollutants can be effectively removed by photocatalytic oxidation, which reveals potential application prospects in the field of wastewater purification. Binary reduced graphene oxide and graphitic carbon nitride (RGO/g-C₃N₄) visible-light photocatalyst was successfully fabricated by the freeze drying assisted thermal polymerization method with urea and dicyandiamide as raw materials, respectively. The morphologies, structures and optical properties were characterized by various techniques. It was found that g-C₃N₄ and RGO nanostructures formed an intimate contact across the heterojunction interface. The photodegradation performances of catalysts were evaluated by removing bisphenol A (BPA) with the activation of persulfate (PS). The results indicated that the photocatalytic activities of photocatalysts were enhanced with the addition of PS as an oxidant and electron acceptor under visible light irradiation (λ>420 nm). Moreover, BPA was almost completely removed by RGO/g-C₃N₄ prepared with urea as raw material in 40 min. After five recovery tests, the removal efficiency of BPA for the catalyst was up to 80% within 40 min under visible light irradiation, which exhibited superior stability.

As a narrow band gap semiconductor, Bi₂WO₆ has great application potential in photo-degradation of organic pollutants, such as tetracycline. In present work, Bi₂WO₆ nanosheets were successfully synthesized by a hydrothermal method and the photo-degradation of tetracycline under visible light irradiation were investigated. XRD, FESEM, TEM and absorption spectra were used to characterize the structure and morphology of the material. It was found that when adding 50 mg Bi₂WO₆ nanosheets into 50 mL of tetracycline solution at pH=8, 85% tetracycline (50 mL, 50 mg/L) was photodegraded within 130 min. The photoelectron-chemical experiments and free radical capture experiments were performed to explore the photo-degradation mechanism. The results show that good photocatalytic performance of Bi₂WO₆ nanosheets are ascribed to the high electron density and photoelectron-hole separation efficiency.

A low-cost oyster shell was carried to prepare biogenic calcium carbonate (bio-CaCO₃) to remediate Pb(II) and methyl orange (MO) from contaminated water. The morphology, composition and structure of the material were analyzed mainly by scanning electron microscope (SEM), thermogravimetric analysis (TGA), X-ray fluorescence (XRF). The adsorption of Pb(II) and MO by bio-CaCO₃ was studied by combining batch experiments and microstructure characterization. Batch sorption experiments showed that 45% MO was removed by bio-CaCO₃ (m_sorbent/V_solvent=0.2 g/L, [MO]_initial=60 mg/L). An obviously morphology change took place after MO adsorbed onto bio-CaCO₃. The maximum sorption capacity of bio-CaCO₃ for Pb(II) is 1775 mg/g (pH=5.0, T=298 K), which is higher than that of the traditional nanomaterials such as bentonite and activated carbon. The Pb(II) removal mechanism is expected to be CaCO₃+ Pb(II)→PbCO₃, where the ΔH ^θ, ΔS ^θ and ΔG ^θ of Pb(II) sorption by bio-CaCO₃ (pH=5.0, T=298K) are -7.64 kJ/mol, -17.92 J/(mol·K) and -2.30 kJ/mol, respectively. More regular products with quadrangular structure are formed after Pb(II) adsorption. The results highlight that the bio-CaCO₃ has a high Pb(II) and MO sorption efficiency, demonstrating that it is a promising adsorbent material in environmental pollution management.

In this work, molecular dynamics (MD) simulations were applied to address the major concerns about the independent and competitive adsorption processes of phenolic organic pollutants (POPs) on the graphene oxide (GO) in aqueous solution. Phenol, α-naphthol and 4-octyl-phenol were adopted as representatives of POPs and their adsorption energies were calculated, which followed an order of 4-octyl-phenol (41.34 kJ/mol)>α-naphthol (33.23 kJ/mol)> phenol (19.31 kJ/mol). The simulation results showed that hydrophobic properties of POPs were recognized as the driving force for their adsorption behaviors. Moreover, van der Waals interaction, electrostatic interaction, as well as hydrogen bonds, may also improve the adsorption capacity of GO towards POPs. The competitive adsorption process revealed that in addition to the direct adsorption onto the GO surface, the molecular aggregation may be another indirect adsorption way existed in the mixed system. Understanding the interaction between GO and POPs in aqueous solution is critical to the design and application of graphene-based materials and our findings are believed to contribute further theoretical basis to the engineering treatment of POPs-containing waste water.