Performance Of Photocatalysts Research Articles

Effect of Vacancy Defects on the Electronic Structure and Optical Properties of Bi4O5Br2: First-Principles Calculations

First-principles calculations based on density functional theory are employed to investigate the impact of vacancy defects on the optoelectronic properties of Bi4O5Br2. The results indicate that vacancy defects induce minimal lattice distortion in Bi4O5Br2 without compromising its structural stability. Oxygen or bromine vacancies are more likely to occur than bismuth vacancies. The introduction of a bismuth vacancy leads to n-type semiconductor behavior in the Bi4O5Br2 system, while the creation of an oxygen vacancy reduces the bandgap and enhances the light absorption capacity. Bi4O5Br2 with three coordinated oxygen vacancies exhibits a higher effective electron–hole pair mass ratio, which is advantageous for the efficient separation of electron–hole pairs. Bi4O5Br2 with three coordinated oxygen vacancies exhibits enhanced absorption and reflection coefficients in the visible-light region compared to other systems, indicating that oxygen vacancy defects significantly promote visible-light absorption and electron–hole separation. This research provides new theoretical insights for understanding and optimizing the performance of photocatalysts based on Bi4O5Br2.

Synergetic Effect of Heterojunction and Sulfur Vacancy on ZnIn2S4/CeO2 to Enhance the Photocatalytic Performance of 5‐Hydroxymethylfurfural into 2,5‐Diformylfuran

AbstractThe efficient separation of photocarriers and facile generation of superoxide radicals are crucial for enhancing the performance of photocatalysts in the selectively photo‐oxidizing 5‐hydroxymethylfurfural (HMF) into 2,5‐diformylfuran (DFF). Herein, a ZnIn2S4/CeO2 composite with S‐scheme heterojunction and sulfur vacancies (SV) is successfully developed through a one‐step hydrothermal method. The optimal catalyst (SV‐ZnIn2S4/CeO2) exhibits excellent catalytic activity with 100% conversion of HMF and 96.1% selectivity of DFF in 80 min under ambient conditions, the production rate of DFF is up to 952.6 µmol g−1 h−1. Intriguingly, the performance remains significant even when the concentration of HMF is increased from 8 to 100 mм. Experimental and theoretical investigations discover that the synergistic effect of S‐scheme heterojunction and sulfur vacancies contribute to the separation of photocarriers and the activation of oxygen, which facilitate the generation of superoxide radicals, thus boosting the catalytic oxidation reactions.

Ethylene Glycol (EG)-Derived Chlorine-Resistant Cu0/TiO2-x for Efficient Photocatalytic Degradation of Nitrate to N2 without Sacrificial Agents at Near-Neutral pH Conditions: The Synergistic Effects of Cu0 and EG Radicals.

The selective photoreduction of nitrate to nontoxic nitrogen gas has emerged as an energy-efficient and environmentally friendly route for nitrate removal. However, the coexisting high-concentration chloride ions in wastewater can exert a significant influence on nitrate reduction due to the competitive adsorption and corrosion of Cl- on photocatalysts. Herein, we prepared ethylene glycol-Cu/TiO2-x (EG-Cu/TiO2-x) through a solvothermal reaction of Cu-doped TiO2 in an EG solution. The photodegradation of nitrate using EG-Cu/TiO2-x without adding sacrificial agents can efficiently occur in near-neutral pH solutions containing 50 mM Cl- with 95.26% of NO3- removal and 76.52% of N2 selectivity. Moreover, the photocatalyst performance remained at a high level after 8 cycles. In this work, NO3- was first converted to NH4+ by Cu0 and Ti3+, followed by the NH4+-to-N2 conversion by photogenerated chlorine free radicals. Compared to HO•, Cl•, and Cl2•-, ClO• is proved to play the predominant role in transforming NH4+ to N2. The EG radicals produced by UV light impede Cl- adsorption on Cu, protecting Cu0 from being corroded. What's more, photoelectrons can reduce Ti4+ to Ti3+ and protect Cu0 from being oxidized, enabling the stability of reactive sites. This work provides novel insights and understanding on designing photocatalysts for NO3- removal in solutions containing chloride ions, highlighting the significance of eliminating Cl- by EG radicals and adjusting the conversion process of NO3- for the efficient removal of NO3-.

Z-Scheme Ag2S-Ag-In2O3 Heterostructure with Efficient Antibiotics Removal under Natural Sunlight.

The widespread distribution of antibiotics in natural waters is a great threat to human health. Photocatalytic degradation is an environmentally friendly technology to remediate antibiotic-polluted waters, driven by endless solar energy. Herein, a Z-scheme Ag2S-Ag-In2O3 heterostructure photocatalyst is prepared to remove antibiotics under environmental conditions. Under natural sunlight (light intensity: ∼78 mW/cm2) irradiation, the optimal Ag2S-Ag-In2O3 (10-ASAIO) exhibits considerable performance for decomposing diverse antibiotics, including norfloxacin (NOR), tetracycline hydrochloride, sulfisoxazole, ciprofloxacin, chlortetracycline hydrochloride, and ofloxacin. The NOR photodegradation rate constant of 10-ASAIO reaches 0.025 min-1, which is 12.50, 5.00, and 6.25 times higher than that of In2O3 (0.002 min-1), Ag-In2O3 (0.005 min-1), and Ag2S-In2O3 (0.004 min-1), respectively. This performance of the 10-ASAIO photocatalyst for decomposing NOR under natural sunlight exceeds most of the previously reported photocatalysts under a xenon lamp. Particularly, due to the intermittency of natural sunlight, a light-emitting diode (LED) lamp (light intensity: 5.1 mW/cm2) is also used as a light source, and 72.20% of NOR can be degraded with irradiation for 12 h. The effects of many water characteristics (water bodies, coexisting inorganic anions, pH, and humic acid) on the degradation performance of 10-ASAIO have been investigated, which exhibits stable degradation efficiency in variable aquatic environments. A 10-ASAIO catalyst-coated frosted glass sheet is fabricated to settle the problem of recovery of powder photocatalysts, and the immobilized catalyst shows outstanding activity and stability to decompose NOR. The photocatalytic mechanism and pathway of degrading NOR over 10-ASAIO have also been systemically investigated and proposed. The ecotoxicity (phytotoxicity and biotoxicity) of the 10-ASAIO photocatalyst and treated NOR solution have been tested by their toxic effects on cabbage seeds and Staphylococcus aureus (S. aureus). This work provides a feasible photocatalytic system for environmental pollutant remediation under natural sunlight or an LED lamp.

Quantitative Spectroscopic Analysis of Surface-Reaching Photoexcited Holes in g-C3N4/TiO2 Z-Scheme Heterojunctions.

The Z-scheme heterojunction has been demonstrated to be effective in tuning the photocatalytic performance of photocatalysts. However, there is still a lack of quantitative and in-depth research on how the Z-scheme heterojunction affects the concentration of surface-reaching photoexcited charges. Here, by combining time-resolved spectroscopies and kinetic analysis, the concentration of surface-reaching photoholes (Ch+(surf)) within g-C3N4/TiO2 Z-scheme heterojunctions was quantitatively analyzed for the first time. Quantitative measurements reveal that Ch+(surf) of the prepared Z-scheme photocatalysts is highly dependent on the g-C3N4 content and the induced Z-scheme heterojunctions at the g-C3N4/TiO2 interface. Encouragingly, we found that a properly engineered Z-scheme heterojunction with close coupling of g-C3N4 and TiO2 can significantly increase the Ch+(surf), leading to nearly a 1.7-fold increase compared with pristine TiO2 samples. Furthermore, a distinct hole trap state-mediated Z-scheme charge transfer mechanism was uncovered in which the intrinsic interface defects at the g-C3N4/TiO2 junction act as hole traps, accelerating interface electron-hole recombination, thereby boosting spatial charge separation and ultimately enriching the Ch+(surf). This work provides insights into understanding and controlling electron pathways and Ch+(surf) in Z-scheme photocatalysis, with implications for the screening of different types of direct Z-scheme photocatalysts.

Spirobifluorene-Based D-A Type Conjugated Polymer Photocatalysts for Water Splitting

Exploring synthetic pathways for efficient photocatalysts has always been a major goal in catalysis. The performance of organic photocatalysts is affected by a variety of complex factors, and how to understand the structure–effect relationship is the key to designing efficient photocatalysts. This work explored the feasibility of constructing large-specific-surface-area conjugated microporous polymers (CMPs) based on stereoscopic units like spirobifluorene and achieving efficient photocatalytic activity by modulating the donor–acceptor (D-A) ratio with dibenzothiophene sulfone. Crosslinked pore structures were successfully constructed, and the specific surface area increased with the ratio of spirobifluorene. When the molar ratio of D-A was 1:20, polymer Spso-3 showed the highest photocatalytic hydrogen production activity, at 22.4 mmol h–1 g–1. The findings indicate that constructing D-A type CMPs should be a promising approach to improving the performance of photocatalytic water separation. The appropriate push–pull effect of the D-A structure promotes the photo-induced separation of electron–hole pairs, and the porous structure built on steric units offers ample space for catalytic reactions. This work could provide case references for structural design and the structure–effect relationship of efficient polymer photocatalysts.

Lyophilization strategy to synthesize ultrafine NaCl template for preparation of photocatalytic BiOCl nanoplates via chemical vapor deposition

Two-dimensional (2D) bismuth oxychloride (BiOCl) has attracted increasing attention in nanoelectronics, catalysis, energy storage, and the environment, attributed to its wide indirect band gap and large surface area. However, the imprecise control of the catalytic site on the substrate makes it challenging to produce 2D BiOCl in large quantities economically. Here, we developed lyophilization to create ultrafine NaCl templates to obtain a higher yield of 2D BiOCl nanoplates than traditional substrates using a chemical vapor deposition (CVD) method. In contrast to ball milling or recrystallization, lyophilization can produce the sodium chloride (NaCl) in the ice lattice domain, resulting in ultrafine NaCl particles after removing water. Moreover, the NaCl particles synthesized by lyophilization showed lower crystallinity with partially distorted structures, such as twisted octahedral structures and the structure with Na+ separated from other atoms by an ice lattice. In addition, our method offers an opportunity to introduce and engineer the oxygen vacancies (OVs) on 2D BiOCl to narrow the band gap, improve the separation of photogenerated carriers, and enhance their photocatalytic efficiency by 17.2 times. Thus, our work opens a new avenue to produce 2D BiOCl by tuning the substrate in CVD growth and inspires a new strategy to promote the performance of 2D photocatalysts.

Green synthesis of novel Z-scheme SnS2/HAp nanocomposite using Ocimum tenuiflorum leaf extract and investigation of its photocatalytic activity.

The present study focuses on the green synthesis of a novel Z-scheme SnS₂/HAp photocatalyst using Ocimum tenuiflorum (tulsi) leaf extract as a stabilizing agent. This approach not only emphasizes sustainability but also adds value to waste by extracting hydroxyapatite (HAp) from Labeo rohita fish scales, addressing the challenge of their disposal. The synthesized photocatalyst was thoroughly characterized using a range of analytical techniques to evaluate its crystal structure, optical properties, morphology, and elemental composition. The photocatalytic activity of the SnS₂/HAp composite was assessed through the degradation of gentian violet (GV) dye, a representative organic pollutant. Various reaction parameters were optimized to enhance the degradation efficiency, and the photocatalyst's performance was further tested across different water matrices. Under optimal conditions, the SnS₂/HAp photocatalyst achieved a maximum photodegradation efficiency of 97.49% with a rate constant of 0.0494min- 1 for GV dye. Additionally, it exhibited an efficiency greater than 70% against other emerging pollutants via advanced oxidation processes (AOP). The enhanced photocatalytic activity was attributed to the formation of a Z-Scheme heterojunction between SnS2 and HAp, which enhanced the charge separation efficiency and delayed the charge recombination. The study also demonstrated the photocatalyst's remarkable reusability, maintaining high performance over five cycles and across various water environments. This highlights its potential as a sustainable solution for the removal of organic pollutants from aqueous streams. Finally, a Z-scheme electron transport mechanism is proposed to explain the photodegradation process of GV dye using the SnS₂/HAp photocatalyst.

Fabrication of CoTiO3/MgIn2S4 S–scheme heterojunctions with efficient charge separation to enhance the photocatalytic activities of hydrogen generation and formaldehyde removal

The efficient separation of photoinduced charge carriers is a primary factor in the catalytic performance of photocatalysts. Constructing S-scheme heterojunctions is a prospective strategy to efficiently and spatially separate photoinduced charges while retaining strong oxidation and reduction capacities of the catalyst system. Herein, CoTiO3/MgIn2S4 (abbreviated x% CTO/MIS, where x% represents the mass ratio of CTO-to-MIS; x = 5, 10, 15, 20, and 25) heterojunctions were successfully synthesized using a hydrothermal method. These heterojunctions exhibited highly efficient and reusable visible-light photocatalytic properties for hydrogen (H2) generation and formaldehyde (HCHO) degradation. Notably, the 15 % CTO/MIS demonstrated an admirable H2 evolution activity of 631.77 μmol·g−1·h−1, with AQE = 2.25 % at λ = 420 nm, and an HCHO degradation rate of 67.18 %. The intermediate products generated during HCHO removal were identified applying in situ diffuse reflectance infrared Fourier transform spectroscopy. The exceptional catalytic performance of the synthesized materials was attributed to the boosted light absorption and utilization, rapidly separation, and transfer of photoproduced charge carriers, which resulted from the internal electric field of the S-scheme mechanism. Moreover, the S-scheme electron transfer pathway for the CTO/MIS catalyst system during the photocatalytic process was confirmed using electron spin resonance spectroscopy, free-radical capturing tests, density functional theory calculations, in situ X-ray photoelectron spectroscopy, and semiconductor energy band theory. The study offers an innovative perspective for establishing S-scheme heterojunctions with highly efficient and stable photocatalytic activity for H2 generation and HCHO removal.

Insight into the Rate-Determining Step in Photocatalytic Z-Scheme Overall Water Splitting by Employing A Series of Perovskite RTaON2 (R = Pr, Nd, Sm, and Gd) as Model Photocatalysts.

Photocatalysis is an intricate process that involves a multitude of physical and chemical factors operating across diverse temporal and spatial scales. Identifying the dominant factors that influence photocatalyst performance is one of the central challenges in the field. Here, we synthesized a series of perovskite RTaON2 semiconductors with different A-site rare earth atoms (R = Pr, Nd, Sm, and Gd) as model photocatalysts to discuss the influence of the A-site modulation on their local structures as well as both physical and chemical properties and to get insight into the rate-determining step in photocatalytic Z-scheme overall water splitting (OWS). It is interesting to find that, with a decreasing ionic radius of the A-site cations, the RTaON2 compounds exhibit continuous blue shift of light absorption and a concomitant reduction in the lifetime of photogenerated carriers, revealing a significant influence of A-site atoms on the light absorption and charge separation processes. On the other hand, the A-site atomic substitution was revealed to significantly modulate the valence band positions as well as surface oxidation kinetics. By employing the Pt-modified RTaON2 as H2-evolving photocatalysts, the activity of photocatalytic Z-scheme OWS for hydrogen production on them is found to be determined by its surface oxidation process instead of light absorption or charge separation. Our results give the first experimental demonstration of the rate-determining step during the photocatalytic Z-scheme OWS processes, as should be instructive for the design and development of other efficient solar-to-chemical energy conversion systems.

A Spin‐Polarized Electron‐Induced MXene‐KBi0.9Co0.1Fe2O5 Photocatalyst for Enhanced Dye Degradation

In photocatalysts aimed to degrade environmental pollutants, photons are generally used as primary stimuli to generate electron–hole pairs to target the chemical bonds to disintegrate. Recently, electron spin has been reported as an essential degree of freedom to improve the performance of photocatalysts. In this work, spin‐polarized electrons and holes are introduced into a brownmillerite KBi0.9Co0.1Fe2O5 semiconductor and a two‐dimensional (2D) MXene composite system by application of an external magnetic field. The spin polarization properties are monitored by measuring the magnetoresistance effect of the MXene‐KBCFO device, which is related to the carrier transfer efficiency. Remarkably, the photocatalytic performance of MXene‐KBCFO is significantly enhanced by the simultaneous application of an external magnetic field and illumination due to the increased number of spin‐polarized photoexcited carriers caused by the synergy effect of the 2D MXene heterostructure together with the ferromagnetic spin ordering. This results in increased reaction hotspots, effective built‐in electric field, extended carrier lifetime, and reduced charge recombination owing to parallel alignment of electron spin orientation. The results show that the efficiency and stability of photocatalytic dye degradation can be effectively enhanced by manipulating the spin‐polarized electrons in the MXene‐based oxide‐perovskite heterostructure photocatalyst.

Enhanced super-ultra-deep photocatalytic oxidative desulfurization by titanium-activated metal-organic frameworks nanophotocataltyst

Addressing the escalating global demand for fossil fuels and the urgent environmental concerns associated with their use necessitates the development and implementation of efficient and cost-effective techniques for the removal of sulfur compounds. In this study, titanium-activated MIL-101(Fe) was utilized for the removal of organosulfur compounds through the photocatalytic oxidation desulfurization (PODS) process. The coexistence of active sites with titanium and iron resulted in an ultra-deep desulfurization. The impact of titanium loading was assessed, with TxML representing the ratio of Ti to Fe (x = 1, 1.5, and 2, respectively). Nanophotocatalysts were fabricated by solvothermal method. The physicochemical properties of the new materials were investigated by performing XRD, TEM, FT-IR, FESEM, EDX, UV–Vis DRS, PL, GC–MS, ESR, TGA, transient photocurrent, and nitrogen adsorption–desorption analyses. The effect of titanium loading on the structure, and performance of photocatalysts in the PODS reaction was investigated. The reaction parameters were optimized for maximum efficiency. Under optimal conditions of T2ML loading at 1.5 g/L, a volumetric solvent to fuel ratio (S/F) of 1, and a temperature of 50 ℃, T2ML shows the best performance by removing 100 % of dibenzothiophene.Kinetic experiments revealed that the PODS reaction obeys a pseudo-first order equation, and activation energy is 47.08 kJ.mol−1.

Study on the regulation mechanism of Al doping on the controllable photocatalytic performance of the ZnO@MgAl-LDH nanocomposite

The ZnO hollow nanospheres were initially prepared using the template method. Subsequently, MgAl-LDH nanosheets were in-situ grown on the surface of the nanospheres via the hydrothermal method, resulting in the synthesis of a type-I heterojunction-based ZnO@MgAl-LDH composite photocatalyst. However, the introduction of Al dopant into the ZnO hollow nanosphere component resulted in an elevation of the Fermi level of ZnO, which led to a change in the heterojunction type in the ZnO@MgAl-LDH composite from type-I to type-II. Consequently, the separation of photo-generated carriers in the Al-doped ZnO@MgAl-LDH composite was significantly enhanced, thereby improving its photocatalytic performance. Moreover, the mass ratio of Al-doped ZnO hollow nanospheres and MgAl-LDH was examined in greater detail to ascertain its influence on the photocatalytic performance of the composite photocatalyst. All Al-doped ZnO@MgAl-LDH composite samples exhibited enhanced photocatalytic performance in comparison to the composite sample without Al doping. Furthermore, when the mass of Al-doped ZnO hollow nanospheres was maintained at 0.100 g and the Mg2+ concentration in the precursor was 0.006530 mol/L, the resulting Al-doped ZnO@MgAl-LDH composite sample demonstrated the most optimal photocatalytic performance among all the investigated samples.

Sulfur vacancies-engineered CaIn2S4 microspheres for enhanced photocatalytic organic pollutant and antibiotic removal

It is an interesting research topic on construction of defect- rich structures to enhance the performance of photocatalysts. In this study, CaIn2S4 photocatalyst containing sulfur vacancy was successfully synthesized using a straightforward solvothermal method. The sulfur vacancy concentration in CaIn2S4 was controlled by adjusting the amount of thioacetamide added during preparation. Among the prepared samples, CaIn2S4-10 sample with excellent photocatalytic performance exhibits superior degradation efficiency (98.2 %) within 50 minutes when the initial methyl orange (MO) concentration was 20 mg/L. Similarly, it shows the highest degradation performance (94 %) against the antibiotic tetracycline hydrochloride (TCH) (20 mg/L). The phase structure, surface element composition, optical properties and other characteristics of the prepared samples were systematically investigated. The findings demonstrate that the CaIn2S4-10 sample exhibits a decreased band gap width and a negatively shifted conduction band position, which enhances its reduction ability and improves its photocatalytic activity.

Synthesis of Quinone‐Amine‐Linked Covalent Organic Frameworks for Boosting the Photocatalytic Removal of Uranium

AbstractCompared to imine covalent organic frameworks (COFs), the superior stability of amine‐linked COFs renders them more suitable for long‐term harsh real‐world environments. Their numerous amine sites can serve as functional groups or be subjected to post‐modification to further enhance the performance of the material. However, the assortment and abundance of amine‐linked COFs via currently lacking due to restricted monomer varieties and synthetic methods. Herein, this study presents an innovative approach for synthesizing quinone‐amine‐linked COFs by directly combining 2,5‐dihydroxy‐1,4‐benzoquinone (DHBQ) with various amine monomers and introduce a novel photocatalyst, DHBQ‐TAPP‐COF, specifically tailored to efficiently reduce uranium in harsh environments. DHBQ‐TAPP‐COF features a unique donor–acceptor structure, with the DHBQ units serving as acceptors because they contain abundant oxygen atoms that facilitate metal ion coordination, thereby enhancing charge carrier separation, carrier utilization, and uranium reduction efficiency. The quinone‐amine linkages offer improved stability, extended π‐conjugation, heightened local polarity, and conductivity, which enable efficient carrier transfer within the material and thus enhance the overall performance of the uranium photocatalyst. The proposed photocatalyst can efficiently reduce U(VI) without sacrificial agents or decomposition to precipitate UO2 at a recovery rate exceeding 98%. This catalyst provides an efficient and convenient strategy for the stable and high‐performance photocatalytic reduction of uranium.

Boosting hydrogen evolution performance of nanofiber membrane-based composite photocatalysts with multifunctional carbon dots

Recent progress in the co-spinning of nanofibers and semiconductor particles offers a promising strategy for the development of photocatalytic devices, solving aggregation and catalyst recovery challenges. However, composite photocatalysts based on nanofiber membranes often suffer from poor conductivity, low hydrophilicity, and easy recombination of photogenerated electron-hole pairs in the semiconductor components. Here, to tackle the aforementioned issues of ZnIn2S4/polyacrylonitrile (ZIS/PAN) nanofiber-based catalysts, we prepared a composite carbon dots/ZnIn2S4/polyacrylonitrile (CZP) nanofiber membrane by blending carbon dots (CDs) with ZIS/PAN using the electrospinning process. The hydrogen evolution performance of the CZP photocatalyst was significantly improved by CDs, which enhanced the hydrophilicity, increased the light absorption, facilitated the transfer of photogenerated electrons, and reduced the recombination of photogenerated electron-hole pairs. Notably, the optimal CZP photocatalyst achieved a hydrogen evolution rate of 2250 μmol g-1h−1, which is about 23 % higher than that of the nanofiber membrane without CDs and 4.55 times higher than that of ZIS particles. The present work successfully improved the CZP nanofiber membrane of photocatalytic hydrogen evolution performance, and the membrane may benefit further device development by eliminating the need for stirring and simplifying the recovery process.

Two-Level regulation photocatalytic activity of Bi2WO6/COFs with ligand engineering and piezoelectric field for Highly-Efficient degradation of antibiotics

Covalent organic frameworks (COFs) have attracted significant attention in photocatalytic water purification due to their structural designability and sufficiently negative conduction band edges. However, the limited oxidation capacity of single COFs and the low utilization rate of photogenerated carriers result in suboptimal catalytic activity. To address these challenges, we propose a two-level regulation strategy that involves ligand engineering and the introduction of a piezoelectric field to enhance the photocatalytic performance of COF-based photocatalysts. In this study, we combined the piezoelectric material Bi2WO6 with COFs modified with different ligands to design a series of Bi2WO6/R-COFs (R=H, F, CH3O) heterojunctions. Modifying COFs with –OCH3 functional group tuned the local electron distribution, thereby remarkably improving photogenerated electrons transfer rate constant. Besides, the incorporation of Bi2WO6 generated a piezoelectric field under ultrasound, which provides a strong driving force for photocatalytic. Meanwhile, the construction of the heterojunctions offered multi-channel for the generation of reactive oxygen species. As a result, the photocatalytic degradation rate of Bi2WO6/CH3O-COFs reached 93.5 % toward sulfamethoxazole within 48 min under ultrasound-coupled light irradiation, which is nearly three times higher than Bi2WO6/H-COFs. Furthermore, Bi2WO6/CH3O-COFs demonstrated superior degradation performance for other pollutants, including p-chlorophenol, bisphenol A, tetracycline, and phenol, with degradation efficiencies of 99.0 %, 98.4 %, 93.5 % and 88.1 %, respectively. This work proposes a two-level modulation strategy that significantly enhances the antibiotic degradation performance of COF-based catalysts, offering a new perspective for the design of photocatalysts for environmental remediation.

Generation of oxygen vacancies in CuO/TiO2 heterojunction induced by diatomite for highly efficient UV–Vis-IR driven photothermal catalytic oxidation of HCHO

Photothermal catalytic oxidation is a promising and sustainable method for the degradation of indoor formaldehyde (HCHO). However, the excessively high surface temperature of existing photothermal catalysts during catalysis hinders the effective adsorption and degradation of formaldehyde under static conditions. Catalyst loading and oxygen vacancies (OVs) modulation are commonly employed strategies to reduce the photothermal catalytic temperature and enhance the efficiency of photothermal catalytic oxidation. In this work, a p-n type CuO/TiO2 heterojunction is successfully loaded onto diatomite using a wet precipitation method. Under the irradiation of a 300W xenon lamp, the prepared composite material achieved a 100% removal rate of HCHO within 2 h, with a 98% conversion rate to CO2, surpassing the performance of both individual photocatalysts and thermocatalysts. Additionally, by adjusting conditions such as light irradiation and temperature, we have demonstrated that this material exhibits synergistic photothermal catalytic properties. Based on HRTEM, XPS, Raman, and EPR analyses, the introduction of diatomite as a catalyst support was shown to effectively increase the number of OVs. Experimental results, along with O2-TPD, photoelectrochemical characterization, and radical detection, demonstrate that the presence of OVs enhances the oxidative efficiency of both photocatalysis and thermocatalysis, as well as the UV–Vis-IR photothermal catalytic performance. The ternary composite material generates weak hydroxyl (•OH) and superoxide (•O2−) radical under high-temperature with dark conditions, indicating its catalytic oxidation activity under this condition. The increase in temperature and the expansion of the spectral range both enhance the generation of these radicals. In summary, this work demonstrates that the use of diatomite as a support increases the material's specific surface area and OVs content, thereby enhancing adsorption and photothermal catalysis. It elucidates the enhanced catalytic degradation mechanism of this mineral-based photothermal catalyst.

Effects of MOF-MoO3-x derivatives synthesis and oxygen defect engineering on photocatalytic CO2 reduction

Photocatalytic conversion of CO2 into valuable fuels is considered a promising approach for the development of sustainable and renewable energy sources. In this study, we utilized Mo-MOF as a precursor to obtain MoO3 by pyrolytic derivatization and treated it to obtain MOF-MoO3-x containing oxygen vacancies as a catalyst for the photocatalytic reduction of CO2 to CO. MOF derivatization altered the morphology of the MoO3, which made the formation of oxygen vacancies easier and facilitated the separation of electron-hole pairs. Meanwhile, the increased specific surface area and the appearance of surface oxygen vacancies enhanced the CO2 adsorption and activation capabilities of MOF-MoO3-x. As a result, MOF-MoO3-x demonstrated a significant enhances in the photoreduction activity of CO2. Its CO yield was 29.1 μmolg−1h−1, which was 3.7 times higher than that of MOF-MoO3 and 2.4 times higher than that of H-MoO3-x. This innovative strategy may provide a new avenue for improving the comprehensive performance of photocatalysts and developing renewable energy sources.

Construction of S/g-C3N4@β-Bi2O3 heterojunction and its photocatalytic degradation of toluene in the gas phase.

In this paper, a modification of g-C3N4 was carried out by combining non-metal doping with the construction of heterojunctions, and a type II heterojunction composite, S/g-C3N4@β-Bi2O3, was prepared. The phase structure, morphology, elemental composition, valence band structure, and light absorption performance of the photocatalyst were analyzed using characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The performance of the composite photocatalyst in the photocatalytic degradation of gaseous toluene, one of the typical volatile organic compounds (VOCs), under simulated solar light was studied. The effects of preparation conditions, toluene concentration, and recycling on the photocatalytic performance of the composite photocatalyst were investigated. The results show that under the optimal preparation conditions, S/g-C3N4@β-Bi2O3 achieved a degradation efficiency of 74.0% for 5ppm toluene after 5h of light irradiation. Although the degradation efficiency decreased to 61.2% after five cycles, it maintained 83% of its initial activity, indicating good stability of the composite photocatalyst. Free radical quenching experiments demonstrated that h+ was the main active species in the photocatalytic degradation of toluene, followed by ·O2-. Based on all experimental results, the migration law of photo-generated charges was analyzed, and a possible photocatalytic mechanism was proposed. In this study, a new material was obtained for the photocatalytic removal of VOCs by improving the photocatalytic properties of g-C3N4.