Hybrid Photocatalyst Research Articles

Polar peripheral substituent-regulated organic/inorganic hybrid photocatalysts promoting the degradation of phenolic pollutants

Constructing surface hybrid inorganic semiconductor photocatalysts with π conjugated structure is considered as an efficient way to improve the photocatalytic performance. Herein, by using porphyrin as light harvester and electron donor, BiOI as electron acceptor and active center, novel inorganic/organic (porphyrin/BiOI) hybrid photocatalysts with improved performance were prepared using impregnation method in non-covalent way. To explore the effects of porphyrin peripheral substituents on the performance of hybrid photocatalysts, four porphyrin/BiOI hybrids with different polar groups (–COOH, –OH, –NH2, –NO2) on the porphyrin substituents were prepared and their performances in the photocatalytic degradation of four phenolic pollutants were evaluated. All porphyrin/BiOI hybrids showed greatly improved photocatalytic activities compared to BiOI, and TCPP/BiOI hybrid containing –COOH groups was the best one. Under visible light irradiation, TCPP/BiOI could realise 100% photodegradation of 4-chlorophenol (4-CP) within 60 min, whose apparent kinetic constant was about 9.4 times that of BiOI. Substantial experimental results and theoretical calculation suggest that the different photocatalytic performances of the porphyrin/BiOI hybrids containing different porphyrin peripheral groups (–NO2 < –NH2 < –OH <–COOH) are highly correlated with the orientation of the dipole moment and the polarity of porphyrin substituent. This work illustrates that fine-tuning of the sensitizer molecular structure is essential to improve the photocatalytic activity of organic molecule-sensitized semiconductors.

Photocatalytic Degradation of Neonicotinoids—A Comparative Study of the Efficacy of Hybrid Photocatalysts

This study deals with the synthesis and characterization of a series of hybrid photocatalysts consisting of different loadings of TiO2, Cd, and Fe on mesoporous SBA-15 material. The prepared samples were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), and tested for the removal of the neonicotinoid insecticide imidacloprid. The results showed that uncalcined 10% Cd-SBA-15 catalyst exhibited the best photocatalytic activity. The photocatalytic degradation of the imidacloprid was carried out in a batch photoreactor at different pH values, and in the presence or absence of additional compounds such as peroxymonosulfate (PMS) and peroxydisulfate (PDS). The best degradation results were achieved at a pH value of 6.5 with 10% Cd/SBA-15. The degradation performance increased with the addition of PMS and PDS. Based on the results of the experimental measurements, Cd/SBA-15 is a good candidate that can show a reasonable degradation efficiency and reactivity, especially in the presence of PDS or PMS.

Constructing carbon-vacancy introduced g-C3N4 coating ZIF-8 with strong adsorption performance and internal electric field for enhanced photodegradation

Graphitic carbon nitride (g-C3N4) is limited in photocatalytic degradation efficiency owing to its weak adsorption capacity and finite charge utilization. In this work, carbon-vacancy defective g-C3N4 (CNP) wrapped around Zeolitic-imidazolate-framework-8 (ZIF-8) photocatalysts (ZCNP) were designed to overcome these drawbacks. ZCNP exhibits strong antibiotic adsorption effect due to π-π interactions and intermolecular forces. Benefitting from abundant carbon-vacancy coordination sites on CNP, ZIF-8 tightly binds to CNP, forming a built-in electric field at the contact interface and efficiently promoting electron-hole separation. Considering the strong adsorption performance combined with efficient electron-hole separation, ZCNP illustrates superhigh photolytic antibiotic activity (6.2 times higher than that of the pristine g-C3N4, 5.0 times higher than that of pure ZIF-8) and can degrade 98 % Doxycycline, 98 % Tetracycline and 61 % Ofloxacin within 30 min. ZCNP also maintains good efficiency in surface water and ground water. Moreover, the radical trapping experiments demonstrate that h+, 1O2 and •O2− have significant effects on the photocatalytic process, while h+ and 1O2 have great effects on the adsorption process. This work will provide novel insights for the design and development of efficient hybrid photocatalysts with high absorption capacity and photolytic activity.

Recent Progress in All‐Solid‐State Z‐Scheme Heterostructures for Photoreduction of CO2

AbstractPhotoreduction of CO2 into valuable fuels using semiconductors has been known as a potential mean to simultaneously alleviate environmental and energy issues. Z‐scheme photocatalytic systems can realize spatial separation of photogenerated charges and ensure strong redox capability simultaneously. Particularly, the all‐solid‐state Z‐scheme photocatalysts for non aqueous redox mediators have been widely used for CO2 reduction. This review provides a comprehensive outlook of the essential components and recent advancements in all‐solid‐state Z‐scheme systems designed for the photocatalytic reduction of CO2, including indirect Z‐scheme, direct Z‐scheme system, and mechanism on Z‐scheme surface. Finally, a brief outlook on the challenges and novel courses within this domain is presented, which will give a rational guideline to improve the efficiency of hybrid photocatalysts for Z‐scheme CO2 reduction.

Construction of surface-rich MoS2 nanoflowers decorated on 2D layered MXene nanohybrid heterostructure for highly efficient and rapid degradation of oxytetracycline

In this study, we successfully developed a hybrid architecture referred to as MoS2@MX, involving the integration of MoS2 layered onto MXene using a straightforward co-precipitation method. This innovative hybrid photocatalyst exhibited remarkable efficiency in removing oxytetracycline (OTC) molecules from aqueous solutions under visible-light irradiation. During the photocatalytic process, both MoS2 and MX played distinct yet complementary roles. MoS2 facilitated efficient electron transfer, while MX contributed to the generation of radicals. This unique collaboration resulted in a noteworthy 99 % oxidation efficiency for OTC degradation within a brief 60 min of visible light exposure in an aqueous environment. The radicals 1O2 and •OH were identified as the principal drivers behind OTC degradation, underscoring the vital role of the hybrid material. Mechanistically, the degradation of OTC involved several key steps, including C–H bond cleavage, de-carboxylation, C–N bond oxidation, and de-chlorination. Importantly, the MoS2@MX hybrid composite demonstrated remarkable stability, maintaining a noteworthy photocatalytic efficiency of 89 % for targeted OTC removal after undergoing five consecutive cycles. In conclusion, this study emphasizes the potential of the MoS2@MX hybrid material as an effective agent for degrading organic OTC compounds within aquatic environments. The hybrid's multifaceted roles and exceptional performance suggest promising applications in sustainable water treatment.

Selective vanadium etching and in-situ formation of δ-Bi2O3 on m-BiVO4 with g-C3N4 nanosheets for photocatalytic degradation of antibiotic tetracycline

Antibiotics play a vital role in treating microbial illnesses, but their presence in water bodies is a global concern. Despite the potential of polymeric graphitic carbon nitrate (g-C3N4) as a photocatalyst for wastewater treatment, its effectiveness is hindered by a fast charge carrier recombination rate. To overcome this challenge, we have developed a novel approach involving the surface etching-oxidation technique to introduce δ-Bi2O3 onto m-BiVO4. Subsequently, the modified δ-Bi2O3/m-BiVO4 (BBV) was synergistically coupled with g-C3N4 (CN) to create a hybrid photocatalyst (BBVCN). The photocatalytic activity of BBVCN was evaluated using tetracycline hydrochloride (TC) as a model wastewater antibiotic pollutant, demonstrating a 92 % degradation of TC within a 1 h reaction time. Total organic carbon analysis demonstrated a TC removal efficiency of 76 %, indicating significant mineralization by BBVCN.

Dicationic Acridinium/Carbene Hybrids as Strongly Oxidizing Photocatalysts.

A new design concept for organic, strongly oxidizing photocatalysts is described based upon dicationic acridinium/carbene hybrids. A highly modular synthesis of such hybrids is presented, and the dications are utilized as novel, tailor-made photoredox catalysts in the direct oxidative C-N coupling. Under optimized conditions, benzene and even electron-deficient arenes can be oxidized and coupled with a range of N-heterocycles in high to excellent yields with a single low-energy photon per catalytic turnover, while commonly used acridinium photocatalysts are not able to perform the challenging oxidation step. In contrast to traditional photocatalysts, the hybrid photocatalysts reported here feature a reversible two-electron redox system with regular or inverted redox potentials for the two-electron transfer. The different oxidation states could be isolated and structurally characterized supported by NMR, EPR, and X-ray analysis. Mechanistic experiments employing time-resolved emission and transient absorption spectroscopy unambiguously reveal the outstanding excited-state potential of our best-performing catalyst (+2.5 V vs SCE), and they provide evidence for mechanistic key steps and intermediates.

Synergetic Effect of Ligand Modification of a Ru(II) Complex Catalyst and Ag Loading for Constructing a Highly Active Hybrid Photocatalyst Using C3N4 for CO2 Reduction

Synergetic Effect of Ligand Modification of a Ru(II) Complex Catalyst and Ag Loading for Constructing a Highly Active Hybrid Photocatalyst Using C₃N₄ for CO₂ Reduction

Sonochemical surface modification of a novel Sm2O3@g-C3N4@Bi2O3 ternary hybrid photocatalyst exhibiting efficient solar light harvesting: Degradation of Azure b and photoelectrochemical water splitting

Engineered Z-scheme photocatalysts have a strong redox activity while also reducing the annihilation of light-induced charge bearers. In this investigation, a solid state twin Z-scheme Sm2O3@g-C3N4@Bi2O3 nanocomposite has been successfully prepared employing bismuth (III) nitrate, samarium chloride and urea as precursor chemicals in a single co-calcination procedure followed by sonochemical surface modification. The formation of flower like multiphasic material is confirmed from SEM and HRTEM images. BET findings suggested the enhancement in specific surface area of Sm2O3@g-C3N4@Bi2O3 and reduced band gap from UV–visible data. Photoluminescence results confirmed the reduction in rate of charge carrier recombination of Sm2O3@g-C3N4@Bi2O3. Presence of samarium is confirmed from XPS analysis. Under direct solar radiation, the surface modified Sm2O3@g-C3N4@Bi2O3 hybrid demonstrated amplified photo-assisted catalytic activity for the degradation of Azure B (AzB) than pristine g-C3N4 and their binary composite Sm2O3@g-C3N4. It is possible to attribute the better solar light absorption, higher separation efficacy of photo-promoted electron-holes to the amplified photo-assisted degradation performance of the Sm2O3@g-C3N4@Bi2O3 composite. The photodegradaton of AzB follows pseudo-first order kinetics and the observed rate constants are 0.0014, 0.0026, and 0.0316 min−1 for g-C3N4, Sm2O3@g-C3N4, and Sm2O3@g-C3N4@Bi2O3 ternary composite. The nanocomposite also demonstrates good stability and recyclability. A unique solid-state twin Z-scheme photocatalytic pathway was also hypothesized in light of the findings. The fabricated ternary hybrid shown efficient photoelectrochemical water splitting reaction for H2 and O2 generation.

In situ irradiated XPS investigation on S-scheme TiO2/Bi2S3 photocatalyst with high interfacial charge separation for highly efficient photothermal catalytic CO2 reduction

The combination of S-scheme heterojunction and photothermal effect is a promising strategy to achieve efficient CO2 photoreduction into solar fuel due to the boosted charge carrier separation efficiency and faster surface reaction rate. Herein, unique photothermal-coupled TiO2/Bi2S3 S-scheme heterojunction nanofibers were fabricated and applied to a full-spectrum CO2 photoreduction system. Density functional theory calculation and experimental analyses have confirmed the generation of the internal electric field and the S-scheme electron transfer pathway, leading to a highly efficient charge carrier separation. Thanks to the excellent photothermal conversion capacity of Bi2S3, the photogenerated electron transfer rate, and surface reaction rate were further accelerated in hybrid photocatalysts. Under the synergistic effect of S-scheme heterojunction and photothermal effects, the optimal TiO2/Bi2S3 nanofibers achieved 7.65 μmol h–1 of CH4 production rate, which is 5.24 times higher than that of pristine TiO2. Moreover, the morphology reconstruction of Bi2S3 in hybrids facilitates the CH4 selectivity was significantly improved from 64.2% to 88.7%. Meanwhile, the CO2 photoreduction reaction route over TiO2/Bi2S3 nanofibers was investigated based on in-situ Fourier transform infrared spectra. This work provides some useful hints for designing highly efficient photothermal-coupled photocatalysts for CO2 photoreduction.

Superior visible-light absorbing Ag@ZnO nanorods hybrid photocatalyst for efficient decomposition of commercial pharmaceuticals tetracycline and amoxicillin

This work assesses the role of the noble metal silver in the visible-light sensitization of UV-active ZnO by introducing a localized plasmonic resonance effect and enhancing the spatial charge carrier separation. We herein synthesize ZnO nanorods via a solvothermal approach, yielding nanorods of length and diameter 1.356 ± 0.619 μm and 120.56 ± 25.09 nm, respectively. Silver nanoparticles are reduced on the surface of ZnO nanorods via the photodeposition route. XRD spectra reveal a high crystallinity and wurtzite-type structure for ZnO with new peaks for cubic phase Ag upon Ag-loading. The diffraction peaks shift upon Ag modification, indicating partial incorporation of Ag into the ZnO lattice. Further, upon Ag-decoration, a slight increase in dislocation density and micro strain is obtained, which could suppress the recombination rate of charge carriers. The DRS spectra reveal a band gap contraction of materials from 3.19 to 2.98 eV with increasing Ag density. The PL spectra confirmed that the optimum Ag concentration of 3 wt% is proficient in harvesting visible light towards high photocatalytic degradation efficiencies of tetracycline (92.1 %) and amoxicillin (76.4 %) in 90 min as compared to 49.4 % and 38 % over pristine ZnO nanorods. TOC studies reveal only partial mineralization of ∼42.7 % (tetracycline) and ∼31.3 % (amoxicillin) due to the formation of reaction intermediates identified by HR-MS chromatograms. In addition, degradation pathways are proposed through the fragments at different m/z ratios.

Efficient methylene blue dye removal using hybrid ZnO/Co/Cs photocatalyst beads

This study highlighted the developments of the hybrid photocatalytic system for wastewater treatment in the textile industry. Chitosan (Cs) and cobalt (Co) were introduced into the conventional catalyst zinc oxide (ZnO) to form the hybrid photocatalyst beads. Four different weight ratios of ZnO/Cs (1:1) and ZnO/Co/Cs (1:1:1, 1:2:1 and 2:1:1) beads were synthesized by the sol-gel method. The photocatalytic degradation properties of the hybrid ZnO/Co/Cs were investigated under visible light irradiation for methylene blue (MB) photodegradation. The study focused on the effect of ZnO/Co/Cs composition ratio, irradiation time and the amount of catalyst loading in the photoreactor for five hours of exposure time. The result was that the 1:1:1 ZnO/Co/Cs photocatalyst beads had the highest degradation rate compared to the other systems. Adding Co to the ZnO/Cs photocatalyst improved the photocatalytic activity by increasing the decolourization percentage of methylene blue

Emergence of S-scheme-derived Ag decorated CuBi2O4/CNTs/(BiO)2CO3 photocatalyst with enhanced visible light photocatalytic performance

BackgroundDue to advantages like low cost, and high catalytic efficiency, photocatalysis has attracted more and more attention. The present investigation presents a straightforward and cost-effective hydrothermal method for producing Ag-decorated CuBi2O4/CNTs/(BiO)2CO3 composites with varying weight percentages of (BiO)2CO3. MethodsHerein, systematic investigations were conducted to examine the crystal, morphological, and optical properties of the photocatalysts. The investigation focused on evaluating the photocatalytic performance via visible light-assisted photodegradation of methyl orange (MO) and rhodamine B (RhB). Significant findingsFindings revealed that loading of (BiO)2CO3 efficiently improved the photoactivity of the composite. The Ag-CuBi2O4/CNTs/(BiO)2CO3 heterojunction photocatalyst with 15 % loading of (BiO)2CO3 has expressively enhanced photocatalytic performance, estimated around 97.79 % of RhB and 98.29 % of MO photo-degraded within 70 min in visible light irradiation, which was also found much enhanced than that of bare CuBi2O4 and (BiO)2CO3. Re-cyclic experiments indicated that fabricated semiconductor hybrid photo-catalyst own good photo-stability as well as reusability. The involvement of ∙O2- and ∙OH active radical species in the process of increased photo-degradation has been demonstrated using ESR and radical trapping tests. The description of the full photocatalytic mechanism based on the S-scheme was conducted by considering the estimated energy band locations, electron spin resonance (ESR) analysis and reactive oxygen species (ROS) trapping tests. This study presents a pragmatic methodology for the development of wide-bandgap bismuth-derived semiconductors that exhibit effective photo-degradation for environmental remediation.

Fabrication of UiO-66/GCN, a Hybrid Photocatalyst, for Effective Degradation of Ciprofloxacin, Toxicity Estimation, and Its Antibacterial Activity.

Fabrication of a metal-organic framework-based photocatalyst has been gaining much interest due to its higher surface area and reasonable band gap, enhancing its photocatalytic activity. This study attempted a facile synthesis of the hybrid photocatalyst UiO-66 doped with graphitic carbon nitride (GCN) by a simple solvothermal method. This composite minimized the drawback related to photogenerated charge transfer and recombination and helped the absorption of visible light. The material was investigated by using various instrumental techniques. In this work, ciprofloxacin (CIP), a fluoroquinolone drug, was chosen as a target micropollutant, and a photodegradation experiment was carried out by using UiO-66, GCN, and UiO-66/GCN under a visible light source, which exhibited 81.85, 69.48, and 93.60% of degradation, respectively. Finally, liquid chromatography mass spectrometry analysis and theoretical computation were carried out to identify the CIP degradation mechanism, and T.E.S.T. software was used to investigate the toxicity of the intermediate products. Apart from photocatalytic activity, the prepared material was also tested for its antibacterial properties against Staphylococcus aureus and Escherichia coli.

Visible-light-responsive hybrid photocatalysts for quantitative conversion of CO2 to highly concentrated formate solutions.

Photocatalysts can use visible light to convert CO2 into useful products. However, to date photocatalysts for CO2 conversion are limited by insufficient long-term stability and low CO2 conversion rates. Here we report hybrid photocatalysts consisting of conjugated polymers and a ruthenium(ii)-ruthenium(ii) supramolecular photocatalyst which overcome these challenges. The use of conjugated polymers allows for easy fine-tuning of structural and optoelectronic properties through the choice of monomers, and after loading with silver nanoparticles and the ruthenium-based binuclear metal complex, the resulting hybrid systems displayed remarkably enhanced activity for visible light-driven CO2 conversion to formate. In particular, the hybrid photocatalyst system based on poly(dibenzo[b,d]thiophene sulfone) drove the very active, durable and selective photocatalytic CO2 conversion to formate under visible light irradiation. The turnover number was found to be very high (TON = 349 000) with a similarly high turnover frequency (TOF) of 6.5 s-1, exceeding the CO2 fixation activity of ribulose-1,5-bisphosphate carboxylase/oxygenase in natural photosynthesis (TOF = 3.3 s-1), and an apparent quantum yield of 11.2% at 440 nm. Remarkably, quantitative conversion of CO2 (737 μmol, 16.5 mL) to formate was achieved using only 8 mg of the hybrid photocatalyst containing 80 nmol of the supramolecular photocatalyst at standard temperature and pressure. The system sustained photocatalytic activity even after further replenishment of CO2, yielding a very high concentration of formate in the reaction solution up to 0.40 M without significant photocatalyst degradation within the timeframe studied. A range of experiments together with density functional theory calculations allowed us to understand the activity in more detail.

Air promotes efficient and selective CO2 photoreduction with a molecule/semiconductor hybrid photocatalyst: the significant role of simultaneous photodegradation of organic pollutants

A molecule/semiconductor hybrid photocatalyst, consisting of carbon nitride integrated with a molecular Ni(ii)–terpyridine complex, has been employed for air-promoted CO2 photoreduction with the simultaneous photodegradation of tetracycline.

A strontium doped p–n heterojunction TiO2/Sr–Co3O4 composite for enhanced photocatalytic degradation of MG dye under solar light irradiation

Surface water purification by hybrid photocatalyst under solar irradiation.

Enhanced charge mediator properties of photocatalysts with reduced graphene nanoribbons for photocatalytic acceleration of hydrogen production in aqueous media

In this study, a hybrid photocatalyst with titanium oxide using reduced graphene nanoribbons (rGNR) was fabricated.

Intense interaction between biochar/g-C3N4 promotes the photocatalytic performance of heterojunction catalysts.

In recent decades, environmental protection and energy issues have gained significant attention, and the development of efficient, environmentally friendly catalysts has become especially crucial for the advancement of photocatalytic technology. This study employs the sintering method to produce biochar. A hybrid photocatalyst for the degradation of RHB under visible light was prepared by loading varying proportions of biochar onto g-C3N4 using ultrasonic technology. Among them, 2% CGCD (2% biochar/g-C3N4) achieved a degradation rate of 91.3% for RHB after 30 minutes of visible light exposure, which was more than 25% higher than GCD (g-C3N4), and exhibited a higher photocurrent intensity and lower impedance value. The enhancement in photocatalytic activity is primarily attributed to the increased utilization efficiency of visible light and the electron transfer channel effect from a minor amount of biochar, effectively reducing the recombination of photo-generated charge carriers on the g-C3N4 surface, thereby significantly improving photocatalytic activity. The degradation of RHB is synergistically mediated by O2 -, h+ (photo-generated holes), and ˙OH. The free radical capture experiment indicates that O2 - and ˙OH are the primary active components, followed by h+.

Silicon nanocrystal hybrid photocatalysts as models to understand solar fuels producing assemblies

A rhenium metal complex tethered to a silicon quantum dot allows exploration of the effects of catalyst anchoring and Re–Si energetic alignment on photocatalytic CO2 reduction activity.