An excellent Z-scheme Ag2MoO4/Bi4Ti3O12 heterojunction photocatalyst: Construction strategy and application in environmental purification

Unraveling charge transfer dynamics in AgBr/Bi4Ti3O12/Bi2Sn2O7 ternary S-scheme heterojunction photocatalyst

In this study, AgBr/Bi4Ti3O12/Bi2Sn2O7 (ABr/BTO/BSO) composites were successfully synthesized to facilitate multi-channel fast charge transfer. This directs the charge carriers to travel along multichannel pathways and suppresses carrier recombination. The mechanisms underlying charge transfer in the dual S-scheme heterojunction composites were elucidated using density functional theory (DFT) and in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS). Furthermore, electron spin resonance (ESR) and burst experiments verified h+, ·O2 -, and ·OH as the primary active species in the catalytic process. The ABr/BTO/BSO composites demonstrated exceptional photocatalytic redox capabilities, completely degrading rhodamine B (RhB) and achieving degradation rates of 77.21% for tetracycline (TC) and 81.04% for Cr (VI). Both experimental and theoretical analyses confirmed the intrinsic efficacy of photo-induced electron movement within the composites. This research introduces innovative design concepts and strategies for the advanced exploration of electron channel transfer in ABr/BTO/BSO ternary composites and the development of novel composite photocatalytic systems.

Constructing Direct Z-Scheme Y2TmSbO7/GdYBiNbO7 Heterojunction Photocatalyst with Enhanced Photocatalytic Degradation of Acetochlor under Visible Light Irradiation

This study presents a pioneering synthesis of a direct Z-scheme Y2TmSbO7/GdYBiNbO7 heterojunction photocatalyst (YGHP) using an ultrasound-assisted hydrothermal synthesis technique. Additionally, novel photocatalytic nanomaterials, namely Y2TmSbO7 and GdYBiNbO7, were fabricated via the hydrothermal fabrication technique. A comprehensive range of characterization techniques, including X-ray diffractometry, Fourier-transform infrared spectroscopy, Raman spectroscopy, UV-visible spectrophotometry, X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray energy-dispersive spectroscopy, fluorescence spectroscopy, photocurrent testing, electrochemical impedance spectroscopy, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance, was employed to thoroughly investigate the morphological features, composition, chemical, optical, and photoelectric properties of the fabricated samples. The photocatalytic performance of YGHP was assessed in the degradation of the pesticide acetochlor (AC) and the mineralization of total organic carbon (TOC) under visible light exposure, demonstrating eximious removal efficiencies. Specifically, AC and TOC exhibited removal rates of 99.75% and 97.90%, respectively. Comparative analysis revealed that YGHP showcased significantly higher removal efficiencies for AC compared to the Y2TmSbO7, GdYBiNbO7, or N-doped TiO2 photocatalyst, with removal rates being 1.12 times, 1.21 times, or 3.07 times higher, respectively. Similarly, YGHP demonstrated substantially higher removal efficiencies for TOC than the aforementioned photocatalysts, with removal rates 1.15 times, 1.28 times, or 3.51 times higher, respectively. These improvements could be attributed to the Z-scheme charge transfer configuration, which preserved the preferable redox capacities of Y2TmSbO7 and GdYBiNbO7. Furthermore, the stability and durability of YGHP were confirmed, affirming its potential for practical applications. Trapping experiments and electron spin resonance analyses identified active species generated by YGHP, namely •OH, •O2-, and h+, allowing for comprehensive analysis of the degradation mechanisms and pathways of AC. Overall, this investigation advances the development of efficient Z-scheme heterostructural materials and provides valuable insights into formulating sustainable remediation strategies for combatting AC contamination.

The Fabrication and Property Characterization of a Ho2YSbO7/Bi2MoO6 Heterojunction Photocatalyst and the Application of the Photodegradation of Diuron under Visible Light Irradiation

A novel photocatalytic nanomaterial, Ho2YSbO7, was successfully synthesized for the first time using the solvothermal synthesis technique. In addition, a Ho2YSbO7/Bi2MoO6 heterojunction photocatalyst (HBHP) was prepared via the hydrothermal fabrication technique. Extensive characterizations of the synthesized samples were conducted using various instruments, such as an X-ray diffractometer, a Fourier transform infrared spectrometer, a Raman spectrometer, a UV-visible spectrophotometer, an X-ray photoelectron spectrometer, and a transmission electron microscope, as well as X-ray energy dispersive spectroscopy, photoluminescence spectroscopy, a photocurrent test, electrochemical impedance spectroscopy, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance. The photocatalytic activity of the HBHP was evaluated for the degradation of diuron (DRN) and the mineralization of total organic carbon (TOC) under visible light exposure for 152 min. Remarkable removal efficiencies were achieved, with 99.78% for DRN and 97.19% for TOC. Comparative analysis demonstrated that the HBHP exhibited markedly higher removal efficiencies for DRN compared to Ho2YSbO7, Bi2MoO6, or N-doped TiO2 photocatalyst, with removal efficiencies 1.13 times, 1.21 times, or 2.95 times higher, respectively. Similarly, the HBHP demonstrated significantly higher removal efficiencies for TOC compared to Ho2YSbO7, Bi2MoO6, or N-doped TiO2 photocatalyst, with removal efficiencies 1.17 times, 1.25 times, or 3.39 times higher, respectively. Furthermore, the HBHP demonstrated excellent stability and reusability. The mechanisms which could enhance the photocatalytic activity remarkably and the involvement of the major active species were comprehensively discussed, with superoxide radicals identified as the primary active species, followed by hydroxyl radicals and holes. The results of this study contribute to the advancement of efficient heterostructural materials and offer valuable insights into the development of sustainable remediation strategies for addressing DRN contamination.

Photocatalysis Meets Piezoelectricity in a Type-I Oxygen Vacancy-Rich BaTiO3/BiOBr Heterojunction: Mechanism Insights from Characterizations to DFT Calculations

It is a challenging task to design a piezoelectric photocatalyst with excellent performance under mechanical agitation instead of ultrasonic irradiation. Integrating vacancy defects into a heterojunction seems to be an effective strategy for synergistically increasing its piezo-photocatalytic performance. For this goal, a two-step hydrothermal method was adopted to architect a type-I oxygen-vacancy-rich BaTiO3/BiOBr heterojunction to surge the degradation of Rhodamine B (RhB) under the combined action of simulated sunlight irradiation and mechanical agitation. Various instrumental techniques demonstrated the formation of a BaTiO3/BiOBr heterojunction with high crystallinity. The existence of surface oxygen vacancies was confirmed by XPS and EPR tests. PFM results manifested that this heterojunction had excellent piezoelectric properties, with a piezoelectric response value of 30.31 pm V-1. Comparative experiments indicated that RhB degradation efficiency under piezo-photocatalysis over this heterojunction largely exceeded the total sum of those under piezocatalysis and photocatalysis. h+, ·O2-, and 1O2 were the dominant reactive species for RhB degradation. The improved separation efficiency of photogenerated charges was verified by electrochemical measurements. DFT calculations indicated that the polarization of BaTiO3 could affect the electronic band structure of BiOBr. This work will provide comprehensive insights into piezo-photocatalytic mechanism at a microcosmic level and help to develop new-styled piezoelectric photocatalysts.

UV-light-responsive Ag/TiO2/PVA nanocomposite for photocatalytic degradation of Cr, Ni, Zn, and Cu heavy metal ions

The rapid growth of industrialization has led to the uncontrolled pollution of the environment, and rapid action is needed. This study synthesized Ag/TiO2/polyvinyl alcohol (PVA) nano photocatalyst for promising light-derived photocatalytic removal of heavy metal ions. The design of experiment (DOE) was used to study the effect of important factors (pH, reaction time, and photocatalyst dosage) to maximize the final performance of the photocatalyst. In the optimized condition, the Ag/TiO2/PVA nano-photocatalyst removed more than 94% of Cr6+ in 180 min, and the efficiency was more than 70% for Cu2+, Zn2+, and Ni2+ metal ions. The adsorption of the heavy metal ions on the photocatalyst was described well with the Langmuir isotherm, while the pseudo-second-order linear kinetic model fitted with the experimental data. The nano-photocatalyst's stability was confirmed after maintaining its performance for five successive runs. The enhanced photocatalytic activity for the heavy metal ions removal can be attributed to the presence of metallic silver nanoparticles (electron transfer and plasmonic fields mechanisms) and PVA, which delayed the recombination of electron-hole. The synthesized ternary Ag/TiO2/PVA nano-photocatalyst showed promising performance for the elimination of heavy metal ions and can be used for environmental remediation purposes.

Atomically dispersed dual-atom catalysts: A new rising star in environmental remediation

Single-atom catalysts, characterized by individual metal atoms as active centers, have emerged as promising candidates owing to their remarkable catalytic efficiency, maximum atomic utilization efficiency, and robust stability. However, the limitation of single-atom catalysts lies in their inability to cater to multistep reactions using a solitary active site. Introducing an additional metal atom can amplify the number of active sites, modulate the electronic structure, bolster adsorption ability, and enable a gamut of core reactions, thus augmenting their catalytic prowess. As such, dual-atom catalysts have risen to prominence. However, a comprehensive review elucidating the realm of dual-atom catalysts in environmental remediation is currently lacking. This review endeavors to bridge this gap, starting with a discourse on immobilization techniques for dual-atom catalysts, which includes configurations such as adjacent atoms, bridged atoms, and co-facially separated atoms. The review then delves into the intrinsic activity mechanisms of these catalysts, elucidating aspects like adsorption dynamics, electronic regulation, and synergistic effects. Following this, a comprehensive summarization of dual-atom catalysts for environmental applications is provided, spanning electrocatalysis, photocatalysis, and Fenton-like reactions. Finally, the existing challenges and opportunities in the field of dual-atom catalysts are extensively discussed. This work aims to be a beacon, illuminating the path towards the evolution and adoption of dual-atom catalysts in environmental remediation.

Jointly augmented photocatalytic NO removal by S-scheme Bi12SiO20/Ag2MoO4 heterojunctions with surface oxygen vacancies

The deep oxidation of NO molecules to NO₃^- species with the avoidance of toxic NO₂ generation is a big and challengeable concern, which can be solved by the rational design and construction of catalytic systems with satisfactory structural and optical features. For such, in this investigation binary composites Bi₁₂SiO₂₀/Ag₂MoO₄ (BSO-XAM) were fabricated through a facile mechanical ball-milling route. From microstructural and morphological analyses, heterojunction structures with surface oxygen vacancies (OVs) were simultaneously created, contributing to the enhanced visible-light absorption, reinforced migration and separation of charge carries, and further boosted generation of reactive species such as superoxide radicals and singlet oxygen. Based on the density-functional theory (DFT) calculations, surface OVs induced the strengthened adsorption and activation of O₂, H₂O, and NO molecules and oxidation of NO to NO₂, while heterojunction structures were beneficial for the continuous oxidation of NO₂ to NO₃^- species. Thus, the heterojunction structures with surface OVs synergistically guaranteed the augmented photocatalytic NO removal and constrained NO₂ generation of BSO-XAM through a typical S-scheme model. This study may provide scientific guidances for the photocatalytic control and removal of NO at ppb level by Bi₁₂SiO₂₀-based composites through the mechanical ball-milling protocol.

Potential of novel dual Z-scheme carbon quantum dots decorated MnIn2S4/CdS/Bi2S3 heterojunction for environmental applications

In this work, CQDs decorated MnIn₂S₄/CdS/Bi₂S₃ heterojunction was prepared successfully by hydrothermal technique for photocatalytic disinfection of Escherichia coli (E. coli) and mineralization of methyl orange (MO) dye. The charge transferal route and mineralization process in CQDs-MnIn₂S₄/CdS/Bi₂S₃ heterojunction were comprehensively investigated by advanced spectroscopic techniques. The improved visible-light activity and enhanced photo-generated charge transferal efficacy caused dual Z-scheme CQDs-MnIn₂S₄/CdS/Bi₂S₃ heterojunction to achieve boosted photodegradation ability. The catalytic degradation trend was followed as CQDs-MnIn₂S₄/CdS/Bi₂S₃ > MnIn₂S₄ > CdS > Bi₂S₃. The dye was mineralized within 180 min under visible light irradiation. The effect of reaction parameters, pH effect, catalyst dosage, and H₂O₂ addition on MO degradation was also investigated. The degradation rate was maximal at pH 4 with a pseudo-first-order rate constant, 0.0438 min^-1. The assessment of antibacterial properties revealed that CQDs-MnIn₂S₄/CdS/Bi₂S₃ composite effectively inactivated E. coli under visible light. Scavenging experiments, transient photocurrent response, and electron spin resonance spectroscopy suggested that ^•[Formula: see text] and holes were the dominant reactive species. The Z-scheme heterojunction is recyclable up to ten photocatalytic cycles according to recycling experiments. This research indicates the importance of dual Z-scheme CQDs decorated MnIn₂S₄/CdS/Bi₂S₃ heterojunction in wastewater remediation.

An endophytic fungus, Penicillium simplicissimum conjugated with C60 fullerene for its potential antimitotic, anti-inflammatory, anticancer and photodegradation activities

In the present study, endophytic fungus, Penicillium simplicissimum isolated from Loranthus micranthus was used to analyze phytochemical studies by qualitative and GC-MS methods. The endophytic fungus P. simplicissimum yielded novel compound penisimplicissin identified through GC-MS studies. Further, P. simplicissimum was conjugated with C60 fullerene nanoparticles (Ps-FNPs) were verified using UV-vis spectra, XRD, FTIR, DLS, EDX and SEM. Ps-FNPs was confirmed using UV-visible spectra with a peak at 260 nm. The IR bands were recorded at 2085, 1428, 1181, 661, 652, 644, 628, and 604 cm-1. The Ps-FNPs treated cells showed a nucleolar shrinkage and cell arrest atprophase, binuclear and multinucleolar cells, a chromosomal bridge and diversion at anaphase was observed, whereas, chromosomal fragment and abnormal distribution at metaphase stage. The Ps-FNPs exhibited a noteworthy anticancer activity on lung cancer cell line H1975 through cytotoxicity. The cytotoxicity was induced by increasing caspase-3, 7, and 9 activities and also showed highest inhibition in xanthine oxidase and COX-II assay proved good anti-inflammatory activity. Ps-FNPs have been extensively studied for photocatalytic activity test against Rhodamine B, Methylene blue and nigrosine showed potential dye degradation in the presence of sunlight proved to be novel photocatalysts. With all the results recorded, Ps-FNPs also have a synergetic effect having on anti-mitotic, anticancer, anti-inflammation potential and photocatalytic degradation of dyes. Hence, the conjugated Ps-FNPs could be one of the potent nano-drug formulations in future. Thus, the present study gives a clear idea of the multifaceted therapeutic and photocatalytic applications.

Construction of Z-Scheme Ag2MoO4/ZnWO4 Heterojunctions for Photocatalytically Removing Pollutants

Facilitation of the photocarrier separation is a crucial strategy for developing highly efficient photocatalysts in eliminating environmental pollutants. Herein we have developed a new kind of Ag2MoO4/ZnWO4 (AMO/ZWO) composite photocatalysts with a Z-scheme mechanism by anchoring AMO nanoparticles onto ZWO nanorods. Multiple characterization methodologies and density functional theory (DFT) calculations were employed to study the performances of the AMO/ZWO heterojunctions as well as the underlying photocatalytic mechanism. Simulated-sunlight-driven photodegradation experiments for removing methylene blue (MB) demonstrates that the 8%AMO/ZWO heterojunction can photocatalytically remove 99.8% of MB within 60 min, and the reaction rate constant is obtained as 0.10199 min-1, which is enhanced by 6.8 (or 4.9) times when compared with that of pure ZWO (or AMO). On the base of the experimental results and DFT calculations, the enhanced photocatalytic mechanism of the AMO/ZWO heterojunctions was revealed to be the efficient separation of photocarriers via a Z-scheme transfer process. In addition, photodegradion of various organic pollutants over 8%AMO/ZWO was further compared and aimed at incorporating it into industrial application in pollutant removal.

High-Performance Photocatalytic Reduction of Nitrogen to Ammonia Driven by Oxygen Vacancy and Ferroelectric Polarization Field of SrBi4 Ti4 O15 Nanosheets

Photo-responsive semiconductors can facilitate nitrogen activation and ammonia production, but the high recombination rate of photogenerated carriers represents a significant barrier. Ferroelectric photocatalysts show great promise in overcoming this challenge. Herein, by adopting a low-temperature hydrothermal procedure with varying concentrations of glyoxal as the reducing agent, oxygen vacancies (Vo) are effectively produced on the surface of ferroelectric SrBi₄ Ti₄ O₁₅ (SBTO) nanosheets, which leads to a considerable increase in photocatalytic activity toward nitrogen fixation under simulated solar light with an ammonia production rate of 53.41 µmol g^-1 h^-1 , without the need of sacrificial agents or photosensitizers. This is ascribed to oxygen vacancies that markedly enhance the self-polarization and internal electric field of ferroelectric SBTO, and hence, facilitate the separation of photogenerated charge carriers and light trapping as well as N₂ adsorption and activation, as compared to pristine SBTO. Consistent results are obtained in theoretical studies. Results from this study highlight the significance of surface oxygen vacancies in enhancing the performance of photocatalytic nitrogen fixation by ferroelectric catalysts.

Construction of a Z-scheme Ag2MoO4/BiOBr heterojunction for photocatalytically removing organic pollutants

How to facilitate photogenerated-carrier separation is an important step in developing excellent semiconductor photocatalysts for environmental pollutant removal. Herein, Ag₂MoO₄ (AMO) nanoparticles were assembled onto the surface of BiOBr (BOB) nanosheets to construct a highly efficient Z-scheme AMO/BOB heterojunction photocatalyst. Several analytical techniques were used to elucidate the characteristics and photocatalytic mechanism of the AMO/BOB heterojunction. Photodegradation experiments for removing methylene blue under simulated-sunlight irradiation reveal that a 20%AMO/BOB heterojunction exhibits excellent photodegradation activity with η(30 min) = 93.8% and k_app = 0.08638 min^-1, which were greater by 4.5 and 5.6 times in comparison with that of pure BOB and AMO, respectively. Based on the experimental and density functional theory (DFT) calculation results, it is proposed that the Z-scheme carrier transfer/separation mechanism dominates the enhanced photodegradation performance of the composite photocatalysts. Additionally, the potential application of AMO/BOB photocatalysts in degrading various organic pollutants (including organic dyes, antibiotics and other serious organic pollutants) was also investigated.

Antibacterial Z-scheme ZnIn2S4/Ag2MoO4 composite photocatalytic nanofibers with enhanced photocatalytic performance under visible light

Considering the biocompatibility of natural proteins and the strong photo-redox capability of Z-scheme heterojunctions, we fabricated Z-scheme ZnIn₂S₄/Ag₂MoO₄@Zein (Z ZA) photocatalytic membranes via electrospinning and in-situ precipitation for enrofloxacin (ENR) degradation. Z ZA exhibit a fiber structure wrapped with ZnIn₂S₄/Ag₂MoO₄ heterojunctions. Photocatalytic studies and various characterization results certified that the Z-scheme structure between ZnIn₂S₄ and Ag₂MoO₄ significantly increases the lifetime and separation efficiency of photogenerated carriers, which in turn enhances the photodegradation of ENR. The degradation rate of Z ZA-10 (ZnIn₂S₄/10 wt% Ag₂MoO₄@Zein) with the highest catalytic activity could reach 100% within 120 min compared with other samples. For ENR degradation, •O₂^- radicals were certified to be the primary active species by trapping experiments, and several possible conversion pathways of ENR in photocatalytic reactions were proposed. Furthermore, the antibacterial rates of Z ZA-20 (ZnIn₂S₄/20 wt% Ag₂MoO₄@Zein) against B. subtilis, P. aeruginosa, S. aureus, and E. coli could reach 90.09%, 89.78%, 84.34%, and 95.31%, respectively. Antibacterial evaluations and cytotoxicity assays demonstrated that Z ZA photocatalytic films had desirable antibacterial properties and low cytotoxicity, rendering them safe and effective for use in the treatment of antibiotic wastewater.

Highly Efficient Bi4Ti3O12/g-C3N4/BiOBr Dual Z-Scheme Heterojunction Photocatalysts with Enhanced Visible Light-Responsive Activity for the Degradation of Antibiotics

A novel Bi₄Ti₃O₁₂/g-C₃N₄/BiOBr(BTO/CN/BOB) composite was synthesized by a solvothermal-mechanical mixed thermal method. The composition, structure, and micromorphology of the samples were analyzed. The BTO/CN/BOB composite photocatalyst shows better photocatalytic performance for tetracycline hydrochloride (TC) degradation compared to Bi₄Ti₃O₁₂ and binary composite photocatalysts. The highest degradation rate of TC can reach 89.84% using the BTO/CN/BOB photocatalyst under the optimal conditions, and BTO/CN/BOB still exhibits good photocatalytic properties after recycling. Moreover, it also shows good photodegradation activity for different kinds of antibiotics, implying its wide application prospect. The photocatalytic performance and reuse stability of BTO/CN/BOB were significantly improved, which may be because of the enhanced spectral absorption range and efficient electron transfer capability by the synergistic effect and interaction among Bi₄Ti₃O₁₂, BiOBr, and g-C₃N₄. Finally, the possible degradation pathway and electron transfer mechanism of the dual Z-scheme heterojunction are proposed.

In Situ Coupling Carbon Defective C3N5 Nanosheet with Ag2CO3 for Effective Degradation of Methylene Blue and Tetracycline Hydrochloride

The development of novel catalysts for degrading organic contaminants in water is a current hot topic in photocatalysis research for environmental protection. In this study, C₃N₅ nanosheet/Ag₂CO₃ nanocomposites (CNAC-X) were used as efficient photocatalysts for the visible-light-driven degradation of methylene blue (MB), and tetracycline hydrochloride (TC-HCl) was synthesized for the first time using a simple thermal oxidative exfoliation and in situ deposition method. Due to the synergistic effect of nanosheet structures, carbon defects, and Z-scheme heterojunctions, CNAC-10 exhibited the highest photocatalytic activity, with photodegradation efficiencies of 96.5% and 97.6% for MB (60 mg/L) and TC-HCl (50 mg/L) within 90 and 100 min, respectively. The radical trapping experiments showed that ·O₂^- and h⁺ played major roles in the photocatalytic effect of the CNAC-10 system. Furthermore, intermediates in the photodegradation of MB and TC-HCl were investigated to determine possible mineralization pathways. The results indicated that C₃N₅ nanosheet/Ag₂CO₃ photocatalysts prepared in this work could provide an effective reference for the treatment of organic wastewater.

Design of a Lab-On-Chip for Cancer Cell Detection through Impedance and Photoelectrochemical Response Analysis

In this study, a biochip was fabricated using a light-absorbing layer of a silicon solar element combined with serrated, interdigitated electrodes and used to identify four different types of cancer cells: CE81T esophageal cancer, OE21 esophageal cancer, A549 lung adenocarcinoma, and TSGH-8301 bladder cancer cells. A string of pearls was formed from dielectrophoretic aggregated cancer cells because of the serrated interdigitated electrodes. Thus, cancer cells were identified in different parts, and electron-hole pairs were separated by photo-excited carriers through the light-absorbing layer of the solar element. The concentration catalysis mechanism of GSH and GSSG was used to conduct photocurrent response and identification, which provides the fast, label-free measurement of cancer cells. The total time taken for this analysis was 13 min. Changes in the impedance value and photocurrent response of each cancer cell were linearly related to the number of cells, and the slope of the admittance value was used to distinguish the location of the cancerous lesion, the slope of the photocurrent response, and the severity of the cancerous lesion. The results show that the number of cancerous cells was directly proportional to the admittance value and the photocurrent response for all four different types of cancer cells. Additionally, different types of cancer cells could easily be differentiated using the slope value of the photocurrent response and the admittance value.

Template-free synthesis of Bi2O2CO3 hierarchical nanotubes self-assembled from ordered nanoplates for promising photocatalytic applications

In this study, we have adopted a one-step hydrothermal route to synthesize an interesting type of Bi₂O₂CO₃ hierarchical nanotubes self-assembled from ordered nanosheets. The effects of reaction time on the morphological and structural evolution, light absorption properties, photoelectrochemical performance, and photocatalytic performance of the prepared hierarchical nanotubes were investigated. Among the products synthesized at different reaction times, the 3-hour-derived Bi₂O₂CO₃ hierarchical nanotubes were identified to possess the highest photocatalytic performance. To promote the photocatalytic application of the as-synthesized Bi₂O₂CO₃ hierarchical nanotubes, their performance was systematically evaluated via the photodegradation of various organic pollutants (e.g., methyl orange (MO), rhodamine B (RhB), methylene blue (MB), ciprofloxacin (CIP), sulfamethoxazole (SMX) and tetracycline hydrochloride (TC)) and the photoreduction of Cr(VI) under simulated-sunlight irradiation. Furthermore, their photocatalytic performance was also evaluated by purifying simulated industrial wastewater (i.e., a MO/RhB/MB mixed solution) at different pH values and containing different inorganic anions. Based on the experimental data and density functional theory (DFT) calculations, the involved photocatalytic mechanism was discussed.

Rietveld Refinement, Morphology, and Optical and Photoluminescence Properties of a β-Ag1.94Cu0.06MoO4 Solid Solution

Corner-truncated cubic β-Ag_1.94Cu_0.06MoO₄ microcrystals were synthesized using the hydrothermal method. These were investigated by X-ray diffraction, confirming obtention of the spinel structure Fd3̅m. Through Raman spectroscopy are confirmed all modes for the point group of O_h⁷. The E_gap shows a decrease of the band gap from 3.20 to 3.07 eV, with reduction of the conduction band occurring from -0.20 eV (β-Ag₂MoO₄) to -0.13 eV (β-Ag_1.94Cu_0.06MoO₄), suggesting a p-type behavior for the Cu²⁺ ion. The field-emission scanning electron microscopy images confirm the morphological changes for β-Ag₂MoO₄, where potato-like microcrystals were found. Meanwhile, corner-truncated cubic microcrystals for β-Ag_1.94Cu_0.06MoO₄. The photoluminescence (PL) spectrum confirms the increase in the PL emission for β-Ag_1.94Cu_0.06MoO₄, with suppression of the deep defects occurring in the structure caused by oxygen and silver atoms. In contrast, the green region is intensified because of distortions of the Ag-O and Mo-O bonds. Therefore, the β-Ag_1.94Cu_0.06MoO₄ solid solution has PL emission with CCT (4510 K) and CIE coordinates (x = 0.372 and y = 0.433), which could be interesting properties for applications as light-emitting diodes.

Piezoelectric catalytic, photocatalytic and adsorption capability and selectivity removal of various dyes and mixed dye wastewater by ZnO nanoparticles

The C-O functional group decorated ZnO nanoparticles with high UV absorption and VIS/NIR reflectance were synthesized by a simple wet chemistry method using various chelating agents. This study attempts to explore the internal mechanism of the piezoelectric catalytic activity, photocatalytic activity and adsorption performance of ZnO nanoparticles. The phase purity, particle size, optical band gap and photocatalytic activity of ZnO nanoparticles showed strong chelating agent - dependent behavior. The ZnO nanoparticles prepared by using EDTA as a chelating agent exhibits smallest particle size, highest photocatalytic activity for the degradation of methyl orange, methylene blue and rhodamine B, high adsorption capacity for the adsorption of Congo red and high vibration-catalytic performance for the vibration degradation of rhodamine B. The synergies mechanism among piezoelectric catalysis, photocatalysis and adsorption capacity of ZnO nanoparticles are discussed on the basis of the experimental results.

Improved photoredox activity of the 2D Bi4Ti3O12–BiVO4–Bi4V2O10 heterostructure via the piezoelectricity-enhanced charge transfer effect

The formation of the 2D Bi4Ti3O12–BiVO4–Bi4V2O10 heterostructure and the piezoelectric effect on photoredox activity improvements.

Preparation of ZnO/Bi2O3 Composites as Heterogeneous Thin Film Materials with High Photoelectric Performance on FTO Base

In recent years, ZnO nanomaterials have achieved great performance in solar energy applications. How to synthesize a ZnO nanocomposite structure with high photoelectric conversion efficiency has become an urgent problem to solved. In this paper, a narrow band gap bismuth trioxide (Bi2O3) coated on a ZnO nanoarray by magnetron sputtering was used to prepare a composite heterojunction ZnO/Bi2O3. Studies have found that ZnO/Bi2O3 exhibits excellent photoelectric conversion performance. By preparing a composite heterostructure of ZnO/Bi2O3, it can effectively compensate for the insufficient absorption of ZnO in the visible light range and inhibit the recombination of carriers within the material. The influence of Bi2O3 thickness on the microstructure and electronic structure of the ZnO/Bi2O3 composite structure was explored and analyzed. The energy gap width of the composite heterostructure decreases with the increase in the Bi2O3 thickness on the surface of the ZnO nanorod array. At the same time, the conductive glass composite film structure is simple to prepare and is very environmentally friendly. The ZnO/Bi2O3 composite heterogeneous material prepared this time is suitable for solar cells, photodetectors, photocatalysis and other fields.

Broadband Solar Absorber Based on Square Ring cross Arrays of ZnS

Solar energy is an inexhaustible clean energy. However, how to improve the absorption efficiency in the visible band is a long-term problem for researchers. Therefore, an electromagnetic wave absorber with an ultra-long absorption spectrum has been widely considered by researchers of optoelectronic materials. A kind of absorbing material based on ZnS material is presented in this paper. Our purpose is for the absorber to achieve a good and wide spectrum of visible light absorption performance. In the wide spectrum band (553.0 THz-793.0 THz) of the absorption spectrum, the average absorption rate of the absorber is above 94%. Using surface plasmon resonance (SPR) and gap surface plasmon mode, the metamaterial absorber was studied in visible light. In particular, the absorber is insensitive to both electric and magnetic absorption. The absorber can operate in complex electromagnetic environments and at high temperatures. This is because the absorber is made of refractory metals. Finally, we discuss and analyze the influence of the parameters regulating the absorber on the absorber absorption efficiency. We have tried to explain why the absorber can produce wideband absorption.

Design of Narrow-Band Absorber Based on Symmetric Silicon Grating and Research on Its Sensing Performance

In this paper, using the surface plasmon and Fabry–Pérot (FP) cavity, the design of a symmetric silicon grating absorber is proposed. The time-domain finite difference method is used for simulation calculations. The basic unit structure is a dielectric grating composed of silicon dioxide, metal and silicon. Through the adjustment of geometric parameters, we have achieved the best of the symmetric silicon grating absorber. A narrowband absorption peak with an absorption rate greater than 99% is generated in the 3000–5000 nm optical band, and the wavelength of the absorption peak is λ = 3750 nm. The physical absorption mechanism is that silicon light generates surface plasmon waves under the interaction with incident light, and the electromagnetic field coupling of surface plasmon waves and light causes surface plasmon resonance, thereby exciting strong light response modulation. We also explore the influence of geometric parameters and polarization angle on the performance of silicon grating absorbers. Finally, we systematically study the refractive index sensitivity of these structures. These structures can be widely used in optical filtering, spectral sensing, gas detection and other fields.