Photocatalytic Applications Research Articles

Double Layer SiO2-Coated Water-Stable Halide Perovskite as a Promising Antimicrobial Photocatalyst under Visible Light.

Halide perovskite nanocrystals (HPNCs) have emerged as promising materials for various light harvesting applications due to their exceptional optical and electronic properties. However, their inherent instability in water and biological fluids has limited their use as photocatalysts in the aqueous phase. In this study, we present highly water-stable SiO2-coated HPNCs as efficient photocatalysts for antimicrobial applications. The double SiO2 layer coating method confers long-term structural and optical stability to HPNCs in water, while the in situ synthesis of lead- and bismuth-based perovskite NCs into the SiO2 shell enhances their versatility and tunability. We demonstrate that the substantial generation of singlet oxygen via energy transfer from HPNCs enables efficient photoinduced antibacterial efficacy under aqueous conditions. More than 90% of Escherichia coli was inactivated under mild visible light irradiation for 6 h. The excellent photocatalytic antibacterial performance suggests that SiO2-coated HPNCs hold great potential for various aqueous phase photocatalytic applications.

Dye wastewater treatment using nonthermal plasma-treated copper oxide nanoparticles produced through electrolysis technique

Abstract Copper oxide nanoparticles (CuO-NPs) were produced by implementing an electrolysis technique. The prepared CuO-NPs were processed with nonthermal microwave plasma to check the effect of plasma treatment on their morphology and photocatalytic response. The plasma processed and blank CuO-NPs samples were used in dye degradation and water splitting applications under simulated sunlight. The blank sample posed undefined morphology, which turned to spherical particles on plasma processing. The particle size grows slightly with processing time. The blank samples showed a crystallite size of 4.51 nm, which grew to 5.34 nm, 5.40 nm, and 5.49 nm after plasma processing for 10, 20, and 30 min, respectively. The lattice parameter UT sample was measured to be 2.4308, with turned to 3.1091, 3.2112, and 3.3099 after 10, 20, and 30 min of plasma treatment, respectively. Similarly, band gap of CuO-NPs reduced from 2.4 eV to 2.24 eV after plasma processing for 30 min. The porosity of the nanoparticles also showed a similar trend. The plasma processing of CuO-NPs for 30 min produced the best results for photocatalytic water splitting and dye degradation applications. The photocatalytic activity revealed hydrogen evolution of 38.05 mmol.g-1.h-1 and dye removal efficiency of 91%.

Recent innovations in engineering Zinc Oxide (ZnO) nanostructures for water and wastewater treatment: Pushing the boundaries of multifunctional photocatalytic and advanced biotechnological applications

Owing to its rapid advancement in nanotechnology, latest publications (recent 5 years) related to zinc oxide (ZnO) in various aspects and applications have been reviewed. Trend has shifted to the innovation of pristine ZnO nanostructures functionalized with elemental dopants and heterojunction to improve the photoactivities on micropollutant degradation and heavy metals removal as well as the antibacterial effect towards microorganisms. The fundamentals of improved photoactivities (i.e., low recombination rate of charge carrier and effective charge transfer) and enhanced antibacterial properties (i.e., dissolution of ions and generation of reactive oxygen species) are accentuated. Subsequently, a detailed examination is undertaken to elucidate the key impacts of ZnO on actual wastewater treatment systems. This review concludes with a consolidated overview on the recent advances of ZnO for environmental wastewater decontamination and the future prospects on tailoring ZnO based on their photocatalytic and antibacterial properties to match various expectations from practical applications while minimising the adverse impacts on surrounding environment.

Recent Progress in Photocatalytic Applications of Electrospun Nanofibers: A Review.

Electrospun fiber-based photocatalysts demonstrate significant potential in addressing global environmental and energy challenges, primarily due to their high specific surface areas and unique properties. This review examines recent advances in the application of these materials in photocatalytic processes, with a particular focus on water splitting and hydrogen production. The principles of the electrospun method are described in detail, along with the operating parameters, material characteristics, and environmental conditions that affect the fiber formation. Additionally, the review discusses the challenges, advantages, and future prospects of photocatalysts incorporating carbon materials, metals, semiconductors, and hybrid structures with improved performance. These materials have the potential to significantly improve the efficiency of hydrogen energy production, water purification, and CO2 recovery, highlighting their importance in engineering sciences.

Electronic, optical, phonon, and thermodynamic properties of bismuth oxyhalides for photocatalysis application using density functional theory

Bismuth oxyhalide (BiOX) represents a class of layered materials distinguished by unique physicochemical and optical characteristics. This study delivers an extensive investigation into the properties of BiOX crystals, employing first-principles calculations to analyze the electronic band structure, projected density of states (PDOS), Raman and infrared (IR) spectra, dielectric functions, alongside phonon and thermodynamic properties. The computed electronic band gaps BiOI, BiOBr, BiOCl, and BiOF crystals were determined to be 2.19 eV, 3.05 eV, 3.29 eV, and 3.43 eV, respectively. Furthermore, an analysis of the PDOS for each BiOX type indicates that the valence band maximum (VBM) primarily comprises dominant O 2p and halide X np states, while the conduction band minimum (CBM) predominantly features Bi 6p states. In addition, significant absorption edges for BiOI, BiOBr, BiOCl, and BiOF crystals, oriented along the [100] axis, were observed at wavelengths of 540 nm, 449 nm, 367 nm, and 320 nm, respectively. The Raman spectral analysis revealed a noticeable shift correlating with the increasing number of halogen atoms, with intensity enhancements observed at elevated temperatures. Phonon dispersion studies corroborated the geometric stability of the optimized structures of BiOX crystals. Thermodynamic evaluations suggested that BiOX materials exhibit qualities characteristic of hard materials at higher temperatures while displaying softer material attributes at lower temperatures. In summary, this research substantially enriches the current understanding of bismuth oxyhalides by detailing their structural, electronic, optical, phonon, and thermodynamic properties. The findings presented in this study provide a foundational basis for future advancements in photocatalytic applications and material development.

Acoustic-assisted Fabrication, Characterization, and Photocatalytic Application of Ni2O3/NiO/rGO Nanocomposites

Acoustic-assisted Fabrication, Characterization, and Photocatalytic Application of Ni2O3/NiO/rGO Nanocomposites

Influence of non-metals doping on the structural, electronic, optical, and photocatalytic properties of rutile TiO2 based on density functional theory computations

This study investigates the influence of non-metal doping (C, F, N, and S) on the structural, electronic, and optical properties of rutile TiO2 using Hubbard-corrected density functional theory (DFT) within the Quantum ESPRESSO code. Rutile TiO2 is a promising material for environmental remediation and renewable energy applications. However, it has a large bandgap of 3.03 eV, which confines its use to UV light. By substituting oxygen atoms with a single dopant atom, we aim to shift the absorption edge toward the visible spectrum. Our findings reveal that doping with C, N, and S results in a redshift of the bandgap, while F doping does not exhibit this effect. The imaginary part of the dielectric function indicates shifted absorption edges for C, N, and S-doped TiO2, making them suitable for photocatalytic applications. Additionally, an increased refractive index after doping suggests the presence of excess charge carriers that affect light propagation. This work provides valuable insights for experimentalists exploring non-metal doping influences on rutile TiO2 for photocatalysis.

Tetraphenylethene-Based Ni8-Pyrazolate Metal-Organic Framework for Photoredox/Nickel Dual Catalysis of C-S Cross-Coupling.

As a prototypical aggregation-induced emission luminogen (AIEgen), the tetraphenylethene (TPE) moiety has been judiciously modified as organic linkers for constructing various functional metal-organic frameworks (MOFs). However, these AIEgen-based MOFs have rarely received research attention in photocatalytic applications due to their limited stability in harsh reaction conditions. In this work, we report a robust Ni8-pyrazolate-based MOF (denoted as TPE4Pz-Ni) under the guidance of reticular chemistry, which is assembled by an AIE-active tetratopic linker of 1,1,2,2-tetrakis(4-(1H-pyrazol-4-yl)phenyl)ethane (H4-TPE4Pz) with a 12-connected Ni8-cluster of [Ni8(OH)4(H2O)2Pz12] (Pz = pyrazolate) in a (4,12)-connected ftw-a topological network. Notably, MOF TPE4Pz-Ni exhibits excellent stability in a wide range of solvents and even in a saturated NaOH solution. Moreover, its luminescent emission is effectively quenched via a ligand-to-metal charge transfer (LMCT) process originating from the TPE-cored linker to the Ni8 cluster, which enables TPE4Pz-Ni to act as an efficient photoredox/nickel dual catalyst for light-mediated C-S cross-coupling reactions between various aryl iodides and thiols.

Engrossing structural developments of double perovskites for viable energy applications

Investigation for novel functional catalysts illustrates an essential direction in advancing and researching renewable energy. On account of their specific compositional and structural tunability and remarkable stability, double perovskites have been extensively examined as a category of versatile compounds for applications in photocatalysis and electrocatalysis, highlighting them as a promising candidate for catalytic performance and stability. In this review article, we have elaborated on the tunability of double perovskites in terms of their compositions and structures, which proved to be tremendous features for double perovskites in diverse applications. Furthermore, the fabrication methods and the performance optimization comprising band gap tuning of double perovskites have been discussed. The current status of double perovskites for photocatalytic and electrocatalytic H2 production and CO2 reduction, with recent reports, has also been reviewed. Lastly, the challenges and future outlook are put forward.

Phyto-mediated synthesis of ZnO nanoparticles and their sunlight-driven photocatalytic degradation of cationic and anionic dyes

Abstract In this study, zinc oxide-based nanocatalysts were biosynthesized using Ocimum basilicum (OB) and Olea africana (OA) leaf aqueous extracts, termed OB-ZnO and OA-ZnO, as a simple, affordable, and environmentally friendly approach. Their characteristics and efficacy in photodegrading cationic dyes (crystal violet and methylene blue) and anionic dyes (methyl orange and naphthol blue black) were investigated. The catalyst’s properties were analyzed using various techniques, including Fourier transform infrared, X-ray diffraction, photoluminescence, thermogravimetric analysis, UV-Vis, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller. Analysis revealed pure products having a hexagonal wurtzite structure, crystallite sizes of 15.04 and 21.46 nm, surface areas of 23.65 and 7.97 m2/g, particle sizes of 35 and 170 nm with spherical (uniform) and oval-like (non-uniform) shapes, and optical bandgaps of 3.15 and 3.05 eV, respectively. Photocatalytic applications under sunlight indicated excellent activity of both catalysts against targeted cationic and anionic dyes. Most notably, even though OA-ZnO has a lower surface area than OB-ZnO, it demonstrated greater efficiency. The variation in effectiveness is explained by the lower bandgap value of OA-ZnO and its ability to reduce electron–hole recombination due to its larger crystal size, which accelerates the degradation process. Additionally, both catalysts exhibited high stability after being used four times.

Two-dimensional hierarchically porous C3N4 for photocatalysis: perspective and challenges

Owing to its unique structure, porosity and photoresponse properties, two-dimensional hierarchically porous (2D-HP) C3N4 has attracted wide attention in environmental remediation and sustainable energy evolution fields. Up to today, 2D-HP C3N4 has been developed as an efficient photocatalyst for various environmental/energy photocatalytic applications. Its advantages in promoting light harvesting, reactant diffusion and transportation, surface molecule activation and photoinduced carrier separation have been verified. In this perspective, we highlighted the advantages of 2D-HP C3N4 in various photocatalytic reactions such as water splitting and H2O2 production. The relevant mechanism was simultaneously discussed. Moreover, the prospects and obstacles for the industrial utilization of 2D-HP C3N4-based photocatalysts are outlined and summarized. Finally, we envision available approaches for the deployment of 2D-HP C3N4-based materials to promote its practical application.

La2O2MQ2 phases: Stability and synthetic challenges

Oxychalcogenides containing transition metal or p block cations have potential for thermoelectric, photocatalytic and magnetic applications but the synthetic pathways to these quaternary phases are not fully understood. This presents a challenge to the design and preparation of new functional materials. Our combined experimental and computational study of La2O2MQ2 (M = +2 cation; Q = sulfide, selenide anion) systems explores the thermodynamic constraints on synthesis and highlights the subtle balance in stabilities of phases formed via competing reaction pathways.

Synthesis of multifunctional NiFe2O4-Zns-Ag nanocomposite for sunlight driven photocatalytic dye degradation and solar cells applications: Structural, magnetic and optical properties

This article focuses on the fabrication and investigation of the novel multifunctional NiFe2O4-Zns-Ag core-bi-shell nanocomposite and their magnetic optical properties. The nanocomposite was prepared by a simple co-precipitation method and characterized using various techniques such as XRD, SEM, TEM, UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and VSM. The results showed that the nanocomposite had a spinel cubic structure with an average crystallite size of 29 nm. The SEM and TEM images revealed that the nanocomposite had a spherical shape with an average particle size of 61 nm. The optical study demonstrated that the nanocomposite had high absorption in the visible region, indicating its potential for photocatalytic applications. The magnetic study showed that the nanocomposite was superparamagnetic in nature, which could be useful in magnetic separation processes. Furthermore, the potential application of the nanocomposite in solar cells was explored by studying its optical absorption properties. Finally, the photocatalytic activity of the nanocomposite was evaluated using two different azoic dyes under sunlight irradiation. The results showed that the nanocomposite exhibited excellent photocatalytic activity, with a degradation efficiency of 96.22 % within 90 min. Overall, this study provides insights into the potential use of NiFe2O4-Zns-Ag nanocomposite as an efficient photocatalyst for environmental remediation.

Optimizing ligand-to-metal charge transfer in metal–organic frameworks to enhance photocatalytic performance

Metal-organic frameworks (MOFs) have been widely investigated as active photocatalytic material for energy conversion and environmental purification. This review meticulously examines the charge transfer mechanisms within MOFs upon photoexcitation, with a particular emphasis on ligand-to-metal charge transfer (LMCT) and metal-to-ligand charge transfer (MLCT). These processes are essential for the generation and maintenance of effective charge separation, wherein LMCT is especially critical for the photocatalytic applications of MOFs. The analysis begins with an exploration of the charge transfer mechanisms within the MOFs’ structure, assessing the impact of various factors on LMCT, including the metal center, ligand structure, overall spatial configuration and reaction environment. Furthermore, the review provides an in-depth exploration of the advantages and applications of LMCT in photocatalysis. It concludes with an outlook on the future development of LMCT in the field of photocatalysis, underscoring its transformative potential with ongoing research and innovation.

Effect of Aegle marmelos on Magnetite Nanoparticles in Generation of Reactive Oxygen Species Towards the Performance for Photocatalytic and Biological Applications

Effect of Aegle marmelos on Magnetite Nanoparticles in Generation of Reactive Oxygen Species Towards the Performance for Photocatalytic and Biological Applications

Enhanced structural and optical properties of CeO2:ZnO nanocomposites for photocatalysis application

Enhanced structural and optical properties of CeO2:ZnO nanocomposites for photocatalysis application

Prediction of a novel two-dimensional superatomic Cd6S2 monolayer for photocatalytic water splitting.

Two-dimensional transition metal dichalcogenides possess a significant specific surface area, adjustable bandgaps, and excellent optical absorption properties, rendering them highly conducive to photocatalytic applications. Herein, a MoS2-like 2D superatomic Cd6S2 monolayer is predicted, wherein the octahedral Cd6 superatom unit connects with S atoms via six vertices. Chemical bonding analysis reveals that the remarkable dynamic, thermal, and mechanical stability of the Cd6S2 monolayer results from the covalent Cd-S bonds and the 6-center 8-electron (6c-8e) delocalized bond within the Cd6 core, which ensures the chemical octet rule for both the S atom and the Cd6 superatom. Demonstrating notable optical absorption coefficients and a strain-tuned energy band structure, the Cd6S2 monolayer emerges as a viable candidate for catalyzing the solar-powered splitting of water. This work offers an alternative avenue to modify or improve the properties of 2D materials for photocatalytic applications through superatomic assembly.

Optimizing the photocatalytic properties Er-doped bismuth ferrite for the degradation of mixed dyes under sunlight irradiation

In this study, the erbium (Er)-doped bismuth ferrite (BiFeO3/BFO) with the chemical formulation of Bi1-xErxFeO3 (x = 0, 5, 10, and 15 mol%) are synthesized using hydrothermal method. It is found that Er-doping induces structural distortions in BFO, leading to improved electronic and optical properties in BFO as confirmed by XRD, XPS, UV–visible absorption and PL spectral analysis. The particle size of BFO is found to be decreasing in the range of 60–30 nm with Er-doping, observed from their TEM images. Further, the photocatalytic efficiencies of the synthesized Bi1-xErxFeO3 nanoparticles are studied towards the degradation of methylene blue (MB), rhodamine B (RhB) dyes and their mixture under solar irradiation. While all the Er-BFO showed improved efficiency compare to pristine, the 10 mol% Er-doped BFO showed the highest degradation of ∼99 and 94 % for MB and RhB dyes, respectively in 180 min. More interestingly, while the pristine BFO selectively degraded only the MB dye in the MB-RhB mixture, the Er-BFO greatly degraded both the dyes in the mixture, which attributed to their improved electronic, electric field and optical band structure properties, especially to the 10 % Er-BFO degraded around 93 and 78 % of MB and RhB dye in the MB-RhB mixture. The cyclical use of 10 mol% Er-BFO is tested toward the degradation dye mixture, which showed a consistent photocatalytic performance up to 5 cycles, suggesting that the Er-doped BFO is photochemically stable and suitable for sustainable photocatalytic applications.

Synthesis and characterization of zinc-doped hematite nanoparticles for photocatalytic applications and their electronic structure studies by density functional theory

Hematite nanoparticles doped with 1, 3 and 5 % Zn (all % are in molar) were prepared using mechanical alloying. Morphological and phase structure studies using scanning electron microscopy and X-ray diffraction showed nanoparticles possessing a semi-spherical shape and particle size of <50 nm crystallized in rhombohedral structure. The lattice parameters of hematite increased upon Zn doping. The energy-dispersive X-ray and Fourier-transform infrared results demonstrated that Zn was successfully incorporated. The optical behavior of nanoparticles was examined by UV–Vis diffuse reflectance spectroscopy and revealed that Zn doping increased the absorption intensity in the visible light region and decreased the band gap from 1.95 (hematite) to 1.83 eV (3 % Zn). Methylene blue dye degradation by the 3 % Zn sample proved doubling of the photocatalytic activity due to electronic structure modification upon Zn doping. First principles studies using density functional theory performed to investigate the effect of Zn on the electronic band structure of hematite showed that Zn doping caused band gap reduction, causing formation of new energy states, mainly above the valence band. Eventually, the enhancement of Urbach energy and reduction of effective mass, respectively accountable for increasing the relaxation time and mobility of charge carriers, were considered the two main mechanisms regarding the increased photocatalytic behavior of hematite by Zn doping.

Antifouling characteristics and mechanisms in visible-light photocatalytic membrane bioreactor based on g-C3N4 modified membrane

A novel visible-light photocatalytic membrane bioreactor (R3) was constructed for membrane fouling control and effluent quality improvement. Specially, g-C3N4 modified membrane was evaluated for the performance of synergistic separation and photocatalysis. Another two parallel reactors, MBRs with ceramic membrane (R1) and g-C3N4 membrane in dark condition (R2), were operated synchronously for comparison. A satisfactory effluent quality was obtained in R3 with COD and NH4+-N around 22.0 mg/L and 1.02 mg/L during 60-day operation, which was superior to R1 (27.8, 1.42 mg/L) and R2 (29.9, 2.26 mg/L). The thickness of cake layer on membranes in R3 (2.46 μm) was thinner than R1 (3.52 μm) and R2 (4.97 μm) after operation, indicating the introduction of visible light could effectively mitigate membranes fouling. Moreover, microorganism community analysis revealed that visible light increased the relative abundance of Bacteroidetes and Chryseolinea, which not only enhanced the activity of microorganisms in metabolizing organic nutrients, but also improved the transfer and utilization of photogenerated electrons on the semiconductor-microorganism interface. The active aromatic protein metabolism and the upregulated related enzymes further demonstrated the synergistic effect of photocatalysis and microbial communities on the membrane fouling mitigation. This work provides a novel application of photocatalysis into antibiofouling effect in MBRs, and opens a strategy for bacteria inactivation and foulants removal with eco-friendly solar energy.