Combined the Photocatalysis and Fenton-like Reaction to Efficiently Remove Sulfadiazine in Water Using g-C3N4/Ag/γ-FeOOH: Insights Into the Degradation Pathway From Density Functional Theory

Advances in Computational Methods for Modeling Photocatalytic Reactions: A Review of Recent Developments

Photocatalysis is a fascinating process in which a photocatalyst plays a pivotal role in driving a chemical reaction when exposed to light. Its capacity to harness light energy triggers a cascade of reactions that lead to the formation of intermediate compounds, culminating in the desired final product(s). The essence of this process is the interaction between the photocatalyst's excited state and its specific interactions with reactants, resulting in the creation of intermediates. The process's appeal is further enhanced by its cyclic nature-the photocatalyst is rejuvenated after each cycle, ensuring ongoing and sustainable catalytic action. Nevertheless, comprehending the photocatalytic process through the modeling of photoactive materials and molecular devices demands advanced computational techniques founded on effective quantum chemistry methods, multiscale modeling, and machine learning. This review analyzes contemporary theoretical methods, spanning a range of lengths and accuracy scales, and assesses the strengths and limitations of these methods. It also explores the future challenges in modeling complex nano-photocatalysts, underscoring the necessity of integrating various methods hierarchically to optimize resource distribution across different scales. Additionally, the discussion includes the role of excited state chemistry, a crucial element in understanding photocatalysis.

Experimental Study on Kinetics and Mechanism of Ciprofloxacin Degradation in Aqueous Phase Using Ag-TiO2/rGO/Halloysite Photocatalyst

In this study, Ag-TiO2/rGO/halloysite nanotubes were synthesised from natural sources using a simple method. The material was characterised by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Raman spectroscopy, BET, scanning electron microscopy (SEM) and UV-vis DRS techniques. The as-synthesised material has a sandwich-like shape, with the active phase distributed evenly over the rGO/HNT support. Compared to pure TiO2, the material has a lower band gap energy (~2.7 eV) and a suitable specific surface area (~80 m2/g), making it able to participate effectively in the photochemical degradation of pollutants. The catalyst showed exceptional activity in the degradation of CIP antibiotics in water, achieving a conversion of about 90% after 5 h of irradiation at an initial CIP concentration of 20 ppm. This efficiency was significantly higher than that of pure TiO2 and Ag-TiO2, which could prove the important effect of the support and silver doping. The results of the experiments show that the process follows a pseudo-first-order kinetic model in the case of (1%)Ag wt. and pseudo-second-order in the case of (3%)Ag wt., which could be explained by the aggregation of silver and the increasing role of chemisorption. Tests with radical scavengers showed that the •OH radical had the greatest effect on CIP decomposition, while •O2− had the least. The neutral pH value and the high degree of mineralisation (approx. 80%) confirm the potential of the material for use in wastewater treatment.

Degradation of Tetracycline Hydrochloride by a Novel CDs/g-C3N4/BiPO4 under Visible-Light Irradiation: Reactivity and Mechanism

In recent years, with the large-scale use of antibiotics, the pollution of antibiotics in the environment has become increasingly serious and has attracted widespread attention. In this study, a novel CDs/g-C3N4/BiPO4 (CDBPC) composite was successfully synthesized by a hydrothermal method for the removal of the antibiotic tetracycline hydrochloride (TC) in water. The experimental results showed that the synthesized photocatalyst was crystalline rods and cotton balls, accompanied by overlapping layered nanosheet structures, and the specific surface area was as high as 518.50 m2/g. This photocatalyst contains g-C3N4 and bismuth phosphate (BiPO4) phases, as well as abundant surface functional groups such as C=N, C-O, and P-O. When the optimal conditions were pH 4, CDBPC dosage of 1 g/L, and TC concentration of 10 mg/L, the degradation rate of TC reached 75.50%. Active species capture experiments showed that the main active species in this photocatalytic system were holes (h+), hydroxyl radicals, and superoxide anion radicals. The reaction mechanism for the removal of TC by CDBPC was also proposed. The removal of TC was mainly achieved by the synergy between the adsorption of CDBPC and the oxidation of both holes and hydroxyl radicals. In this system, TC was adsorbed on the surface of CDBPC, and then the adsorbed TC was degraded into small molecular products by an attack with holes and hydroxyl radicals and finally mineralized into carbon dioxide and water. This study indicated that this novel photocatalyst CDBPC has a huge potential for antibiotic removal, which provides a new strategy for antibiotic treatment of wastewater.

Photocatalytic Removal of Antibiotics on g-C3N4 Using Amorphous CuO as Cocatalysts

Amorphous CuO is considered as an excellent cocatalyst, owing to its large surface area and superior conductivity compared with its crystalline counterpart. The current work demonstrates a facile method to prepare amorphous CuO, which is grown on the surface of graphitic carbon nitride (g-C3N4) and is then applied for the photocatalytic degradation of tetracycline hydrochloride. The prepared CuO/g-C3N4 composite shows higher photocatalytic activities compared with bare g-C3N4. Efficient charge transfer between g-C3N4 and CuO is confirmed by the photocurrent response spectra and photoluminescence spectra. This work provides a facile approach to prepare low-cost composites for the photocatalytic degradation of antibiotics to safeguard the environment.