Search Results (2,376)

A novel composite material comprising titanium dioxide and layered double hydroxides (TiO₂/LDHs) was innovatively proposed and prepared using the co-precipitation method to overcome the shortcomings of titanium dioxide, such as low efficiency in separating electron–hole pairs induced by light and a low utilization rate of visible light. This material was used to study the visible-light-driven photocatalytic degradation of methylene blue. The experimental results show that by constructing efficient heterojunction structures through the alignment of interface band energies and regulating the interface charge transfer pathways, the recombination rate of photogenerated electron–hole pairs is significantly reduced, and the photocatalytic activity is greatly enhanced. Among the tested samples, the TiO₂/LDHs composite material with an aluminum-to-titanium molar ratio of 1:1 (AT11) demonstrated the best photocatalytic performance. Within 70 min of simulated sunlight exposure, the degradation rate of methylene blue reached 98.2%, and the optimal concentration of the catalyst was 1 g/L. The photocatalytic process follows a first-order kinetic model. After four cycles of use, the degradation efficiency of methylene blue by the AT11 composite material was 78.93%, demonstrating good stability. The free radical capture experiments indicated that the main active substances for the photocatalytic degradation of methylene blue were h⁺ and ·OH. The constructed TiO₂/LDHs heterostructure system significantly enhanced the photocatalytic performance of TiO₂ materials, which was conducive to the efficient utilization of solar energy. Full article

This study presents a comprehensive investigation of a novel graphene oxide/zinc oxide/lignin (GO/ZnO/lignin) nanocomposite for the photocatalytic degradation of methylene blue (MB) and gentian violet (also known as crystal violet, CV) dyes in aqueous solutions. The nanocomposite was synthesized through a hydrothermal method and thoroughly characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). FTIR spectra confirmed the successful incorporation of functional groups from all components, while XRD patterns revealed a well-crystallized structure with characteristic peaks. SEM micrographs showed a uniform, hierarchical morphology and EDX analysis verified the elemental composition and distribution. Under ultraviolet (UV) irradiation, the nanocomposite exhibited remarkable photocatalytic degradation efficiency (~97%) for both MB and CV. Key operational parameters were systematically evaluated, including pH (2–10), catalyst dosage (0.005–0.04 g/20 mL), and initial dye concentration (10–20 ppm). Optimal performance was achieved at pH 10, with a catalyst dosage of 0.03–0.04 g/20 mL and lower dye concentrations. The enhanced photocatalytic activity can be attributed to the synergistic effects coming from GO’s electron transport capabilities, ZnO’s strong photocatalytic activity and lignin’s additional degradation sites. Furthermore, the nanocomposite demonstrated excellent reusability, retaining nearly 60% of its degradation capacity after four cycles, outperforming its individual components. These results highlight the potential of this composite material for sustainable wastewater treatment applications. Full article

In recent decades, photocatalysis has received huge attention as a way to address the main environmental challenges affecting planet Earth. Among these, the control of CO₂ emission and its concentration in the atmosphere, as one of the greenhouse gases causing global warming, is of primary importance. This study focuses on the hydrothermal preparation of doped Ba and Ca-based titanates as efficient photocatalytic materials for CO₂ photoreduction under solar light. The materials were characterized by SEM-EDX, XPS, FT-IR ATR, DRS, CHNS, XRD, and N₂ physisorption analyses, and tested for gas-phase methane production from the target reaction. According to the results, the visible light harvesting properties were significantly improved with C and N doping, where glucose and a bio-based chitosan acted as the C and C+N sources, respectively. In particular, C-Ba-based titanate (CBaT) indicated the highest CH₄ productivity, 2.3 µmol/g_cat, against zero activity of the corresponding bare titanate structure, BaT. The larger surface area and pore volume, as well as its narrower band gap, are suggested as the major reasons for the promising performance of CBaT. This work provides new insights for the facile fabrication of efficient photoactive perovskite materials with the aim of CO₂-to-CH₄ photoreduction under solar light. Full article

Based on the excellent performance of the K(Ta_0.5Nb_0.5)O₃ (KTN) system, this study systematically investigated the mechanism of the influence of metal element (Cd, Sn, Hf) doping on the photocatalytic performance of KTN ferroelectric materials using the density functional theory (DFT) based on first principles. The findings indicate that after metal atom doping, the tolerance factor of doping systems is similar to that of pure KTN crystals, confirming that doping does not compromise its structural stability. However, the ion radius differences caused by doping lead to lattice distortion, significantly reducing the bandgap width. Because the impurity element substituting the Ta site exhibits a lower valence state compared to Ta, holes become the majority carriers, thereby endowing the semiconductor with p-type characteristics. These characteristics effectively suppress electron–hole recombination while enhancing electron transitions. Furthermore, the increase in the dielectric constant of the doped system indicates an enhancement in its polarization capability, which is accompanied by a significant improvement in carrier mobility. The peak of the imaginary part of the dielectric function and the peak of the absorption spectrum both shift towards the low-energy region, indicating that doping has expanded the light response range of the system. Moreover, the effective mass of the holes in all doped systems is significantly higher than that of the electrons, further demonstrating that the introduction of impurities is conducive to hindering the separation of photogenerated electron–hole pairs. These modifications significantly enhance the photocatalytic performance of the systems. Full article

Due to its broad-spectrum antibacterial activity, norfloxacin (NOR) has been widely used over the past few decades. However, the residual NOR in aquatic ecosystems could pose risks to human health from bacteria with resistance genes that potentially cause serious infectious diseases. Herein, a series of bandgap-tunable Zn_xCd_1−xS (x = 0~1) solid solutions were hydrothermally synthesized and used for NOR photodegradation under visible light and natural sunlight. Benefitting from the suitable bandgap, band structure, and unique tetrapod shape nanostructure, the Zn_0.1Cd_0.9S solid solution exhibited the best photocatalytic activity, with high degradation efficiencies of 83.23% and 86.28% under visible light and natural sunlight, respectively, within 60 min, which is remarkable among reported Zn_xCd_1−xS-based photocatalysts and other materials. The in situ reactive-species trapping experiment revealed that holes (h⁺) were the primary species, and a possible photodegradation mechanism was thus suggested. Moreover, Zn_0.1Cd_0.9S also exhibited decent reusability and stability after five cycles of experiments. This work provides a comprehensive exploration of the application of bandgap-tunable Zn_xCd_1−xS solid solutions for NOR photodegradation under visible light and natural sunlight, demonstrating the promising application of as-synthesized Zn_0.1Cd_0.9S in the photocatalytic degradation of antibiotics. Full article

Waste drilling fluids represent a complex gel–colloidal system containing structurally stable polymeric networks and heavy-metal ions that can cause tremendous damage to the ecosystem. The current disposal methods, like solidification/landfills, formation reinjection, and chemical treatment, commonly suffer from high secondary pollution risks, poor resource recovery, and incomplete detoxification. This paper developed a photocatalytic approach to complex gel system treatment by hydrothermally synthesizing a novel sulfur-doped, oxygen-vacancy-modified 3D flower-like xS-BiOBr₀.₅Cl₀.₅ structure which effectively narrowed the bandgap of BiOX and thus significantly enhanced its catalytic activity. The chemical composition, morphology, specific surface areas, and bandgaps of the materials were characterized. The photocatalytic performance and cyclic stability of the materials were measured, and 0.5S-BiOBr_0.5Cl_0.5 showed the best photocatalytic performance. The rhodamine B(RhB) degradation and polymer degradation efficiencies of 0.5S-BiOBr_0.5Cl_0.5 were up to 91% and 79%, respectively, while the Hg(II), Cr(VI), and Cr(III) reduction efficiencies of the material were up to 48.10%, 96.58%, and 96.41%, respectively. The photocatalytic mechanism of the xS-BiOBr_0.5Cl_0.5 materials was evaluated through an oxygen vacancy analysis, active species capture experiments, and density functional theory (DFT) computations. Overall, the xS-BiOBr_0.5Cl_0.5 materials can provide a low-cost and harmless treatment method for waste drilling fluids and promote the “green” development of oil and gas. Full article

The advancement of photocatalytic materials is critical for addressing environmental challenges such as water remediation, where efficient, robust, and reusable systems are in high demand. In this search, the development of hierarchically organized photocatalytic configurations with spatial control over active sites can significantly enhance performance. With this in mind, we present here a novel biomimetic approach for the patterned growth of TiO₂-ZnO photocatalytic heterostructures using solid-binding peptides (SBPs) as molecular linkers. Specifically, using bi-functional SBPs with selective affinity for both oxides, we achieve site-specific, molecularly guided deposition of TiO₂ nanoparticles onto pre-patterned ZnO-coated substrates. Leveraging the specific recognition capabilities and strong binding affinities of the engineered SBPs, the proposed biomimetic methodology allows for the fabrication of well-organized hybrid nanostructures under sustainable conditions. Photocatalytic degradation assays employing methyl orange as a model contaminant indicate that the patterned architecture enhances both the accessibility of the active photocatalytic sites and the recoverability of the material. This reusability is a critical parameter for the practical deployment of photocatalytic systems in water purification technologies. The obtained results underscore the potential of SBP-mediated molecular recognition as a versatile tool for green nanofabrication of functional materials with advanced architectural and catalytic properties. Full article

This study explores a green synthesis approach for creating a nanocomposite material consisting of zinc oxide (ZnO) nanoparticles decorated with reduced graphene oxide (rGO), utilizing Clitoria ternatea flower extract as a biogenic reducing agent. The objective was to leverage the phytochemicals present in the flower extract to form ZnO nanoparticles, enhance their properties through rGO integration, and evaluate their structural and photocatalytic characteristics. The nanocomposite was characterized using a comprehensive suite of techniques, including XRD, FTIR, UV–Vis spectroscopy, DLS, zeta potential, SEM, and EDAX. To assess the in vitro biocompatibility, an MTT assay was performed on the normal fibroblast cell line 3T3L1. The nanocomposite exhibited minimal cytotoxicity with over 86% cell viability at concentrations up to 320 μg/mL. Additionally, hemolysis assays demonstrated that the nanocomposite induced less than 5% hemolysis, indicating excellent hemocompatibility. In an in vivo evaluation, zebrafish embryos exhibited no deformities, and the cumulative hatchability was also not affected up to a dose of 50 μg/mL. The exploration of environmental remediation was studied using bromophenol dye degradation, which showed a 65% dye degradation within 30 min of exposure to the composite and sunlight. The outcome of the study showed successful formation of ZnO and its composite with rGO (CT-rGO-ZnO), exhibiting excellent biocompatibility and improved photocatalytic properties. The material demonstrates promise for applications in environmental remediation and energy-related fields. The environmentally friendly nature of the synthesis approach also makes it a valuable contribution toward sustainable nanotechnology. Full article

The persistence of pharmaceutical pollutants such as ciprofloxacin (CIP) in aquatic environments represents a critical environmental threat due to their potential to induce antimicrobial resistance. Photocatalysis using TiO₂-based materials offers a promising solution for their mineralization; however, the limited visible-light response of TiO₂ and charge carrier recombination restricts its overall efficiency. In this study, Nb-doped TiO₂ nanoparticles were synthesized via the sol–gel method, incorporating Nb⁵⁺, ions into the TiO₂ lattice to modulate the structural and electronic properties of TiO₂ to enhance its photocatalytic performance for CIP degradation under UV and visible irradiation. Comprehensive structural, morphological, and optical analyses revealed that Nb incorporation stabilizes the anatase phase, reduces particle size (from 21.42 nm to 10.29 nm), and induces a slight band gap widening (from 2.85 to 2.87 eV) due to the Burstein–Moss effect. Despite this blue shift, Nb-TiO₂ exhibited significantly improved photocatalytic activity under visible light, achieving 86% CIP degradation with a reaction rate 16 times higher than that of undoped TiO₂. This enhancement was attributed to improved charge separation and higher hydroxyl radical (^•OH) generation, driven by excess conduction band electrons introduced by Nb doping. Density Functional Theory (DFT) calculations further elucidated the electronic structure modifications responsible for this behavior, offering molecular-level insights into Nb dopant-induced property tuning. These findings demonstrate how targeted doping strategies can engineer multifunctional nanomaterials with superior photocatalytic efficiencies, especially under visible light, highlighting the synergy between experimental design and theoretical modeling for environmental applications. Full article

The presence of various Ag species (Ag⁺ ions, Ag clusters, and Ag nanoparticles (NPs)) in Ag-zeolite nanocomposites strongly influences their catalytic, photocatalytic, and antibacterial properties. To tailor materials for specific applications, it is essential to employ strategies that control the redox processes between Ag⁺ and Ag⁰ and facilitate the formation of active Ag-containing composites. In this study, we present a comparative analysis of Ag-zeolite nanocomposites, focusing on their synthesis methods, structural characteristics, and antibacterial activity against Escherichia coli. Ag NPs were synthesized using three approaches: solid-state thermal reduction, chemical reduction in aqueous solutions with a mild reducing agent (sodium citrate, Na₃Cit), and chemical reduction with a strong reducing agent (sodium borohydride, NaBH₄). The resulting materials were characterized by X-ray diffraction (XRD), diffuse reflectance UV–Vis spectroscopy (DR UV–Vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), while antibacterial activity was assessed using biological assays. Microscopic and spectroscopic analyses confirmed the formation of Ag NPs and the co-existence of immobilized Ag⁺ ions within the zeolite framework. The specific influence of the treatment method of Ag⁺-zeolite on the presence of silver species in the nanocomposites and their role in antibacterial properties were evaluated. The highest antibacterial efficiency was observed in the nanocomposite produced by thermal treatment of Ag-exchanged zeolite. Thus, the crucial function of Ag⁺ ions in the mechanism of bacteria cell death was suggested. Full article

Photocatalysis is an emerging technology that harnesses light energy to facilitate chemical reactions. It has garnered considerable attention in the field of catalysis due to its promising applications in environmental remediation and sustainable energy generation. Recently, researchers have been exploring innovative techniques to improve the surface reactivity of ferroelectric materials for catalytic purposes, leveraging their distinct properties to enhance photocatalytic efficiency. With their switchable polarization and improved charge transport capabilities, ferroelectric materials show promise as effective photocatalysts for various reactions, including carbon dioxide (CO₂) reduction. Through a blend of experimental studies and theoretical modeling, researchers have shown that these materials can effectively convert CO₂ into valuable products, contributing to efforts to reduce greenhouse gas emissions and promote a cleaner environment. An artificial neural network (ANN) was employed to analyze parameter relationships and their impacts in this study, demonstrating its ability to manage training data errors and its applications in fields like speech and image recognition. This research also examined changes in charge separation, light absorption, and surface area related to variations in band gap and polarization, confirming prediction accuracy through linear regression analysis. Full article

ZnO-based photocatalysts have attracted significant attention for their potential use in advanced oxidation processes for environmental remediation. However, critical challenges, such as rapid charge carrier recombination and narrow light absorption, and poor long-term stability necessitate material modifications to enhance performance. This review provides a comprehensive and critical analysis of recent developments in ZnO-based photocatalysts, including heterojunctions with metal oxides, carbon-based hybrids, metal/non-metal doping, and metal–organic framework materials. Furthermore, emerging trends, such as the integration of atomistic calculations and machine learning (ML) techniques in material design, property prediction, and the optimization of photocatalytic performance, are critically examined. These modern computationally driven approaches provide new insights into band gap engineering, charge transport mechanisms, and the optimization of synthesis parameters, thereby accelerating the discovery of high-performance ZnO-based photocatalysts. However, their practical integration remains limited due to the availability of high-quality datasets and the lack of interdisciplinary methodologies. The review also discusses key research gaps, including emerging environmental applications, as well as stability and scalability challenges, providing a roadmap for future research in data-driven photocatalysis. By evaluating current research, this review aims to provide a foundation for the modification of next-generation ZnO-based photocatalysts for environmental applications. Full article

Water contamination from textile dyes is a major environmental hazard. This is due to the textile industry serving among the biggest manufacturers, thus the extensive usage of these dyes. Several methods for the treatment of these pollutants have been used; however, they have limitations in terms of cost, forming secondary pollution, and effectiveness. Metal oxides such as tin oxide (SnO₂) have been identified as potential photocatalysts for the degradation of these dyes. The potential of SnO₂-based photocatalysts, especially those made using green techniques, has been at the forefront of current research. The physical and optical properties, green synthesis techniques, and photocatalytic uses of SnO₂ NPs are examined. Furthermore, methods to improve photocatalytic effectiveness through the formation of heterostructures are also explored. Lastly, the conclusion and future perspectives of these materials as suitable candidates for water treatment are highlighted. Full article

Photocatalytic water splitting for hydrogen production is an attractive renewable energy technology, but the oxygen evolution reaction (OER) at the anode is severely constrained by a high overpotential. The two-dimensional vdW ferromagnetic material Fe₃GeTe₂, with its good stability and excellent metallic conductivity, has potential as an electrocatalyst, but its sluggish surface catalytic reactivity limits its large-scale application. In this work, we adapted DFT calculations to introduce surface Te vacancies to boost OER performance of the Fe₃GeTe₂ (001) surface. Te vacancies induce the charge redistribution of active sites, optimizing the adsorption and desorption of oxygen-containing intermediates. Consequently, the overpotential of the rate-determining step in the OER process of Fe₃GeTe₂ is reduced to 0.34 V, bringing the performance close to that of the benchmark IrO₂ catalyst (0.56 V). Notably, the vacancies’ concentration and configuration significantly modify the electronic structure and thus influence OER activity. This study provides important theoretical evidence for defect engineering in OER catalysis and offers new design strategies for developing efficient and stable electrocatalysts for sustainable energy conversion. Full article

Against the backdrop of increasing global warming, exploring sustainable pathways to mitigate the greenhouse effect has become a central issue for the ecological and energy future. Photocatalytic reduction of CO₂ technology shows a broad application prospect due to its ability to directly convert CO₂ into high-value-added hydrocarbon fuels and to use solar energy, a clean energy source, to drive the reaction. However, traditional semiconductor catalysts generally suffer from insufficient activity and poor product selectivity in the actual reaction, which cannot meet the requirements of practical applications. In recent years, sulfur vacancy, as an effective material modulation strategy, has demonstrated a remarkable role in enhancing photocatalytic performance. This paper reviews a series of research reports on sulfur vacancies in recent years, introduces the methods of preparing sulfur vacancies, and summarizes the commonly used characterization methods of sulfur vacancies. Finally, the mechanism of introducing sulfur vacancies to promote CO₂ reduction is discussed, which improves the photocatalytic activity and selectivity by enhancing light absorption, facilitating carrier separation, improving CO₂ adsorption and activation, and promoting the stability of reaction intermediates. This review aims to provide theoretical support for an in-depth understanding of the role of sulfur vacancies in photocatalytic systems and to provide a view on the future direction and potential challenges of sulfur vacancies. Full article