Composite Photocatalyst Research Articles

Loading of Ce and n co-doped TiO2 composites onto modified shell powder synergism of adsorption and photocatalysis phytic acid removal: performance and mechanism

Phytic acid was investigated as an organophosphorus pollutant. Titanium dioxide (TiO2) doped with Ce and N was prepared using the sol-gel method and loaded onto a modified shell power to produce modified shell powder/Ce-N-TiO2 (Msp/CeNT). The combined effects of adsorption and photocatalysis on phytic acid were explored. The actual phytic acid degradation rate with the composite photocatalyst was higher than the sum of the adsorption removal rate of phytic acid using the modified shell powder and the photocatalytic degradation removal rate of phytic acid using the Ce-N-TiO2 photocatalyst. Msp/CeNT synergistically affected adsorption and photocatalytic degradation. The effects of different factors, such as reaction temperature, catalyst dosage, initial pH, stirring speed, and light intensity, on the combined effect were investigated. The results showed that the synergistic effect increases with the increase of light intensity. Increasing the reaction temperature, catalyst dosage, initial pH, and stirring speed first increased and then decreased the synergistic effect of the composite photocatalysts. Phytic acid (69.54%) was degraded within 4 h when the temperature, pH, catalyst dosage, stirring speed, and light intensity were 25 °C, 5, 1 g/L, 300 rpm, and 500 W, respectively. We investigated and prepared a composite photocatalytic material, developing a new theoretical method for degrading organophosphorus dissolved in water and providing a basis for treating lake eutrophication as a practical application.

Fabrication of shaddock peel biochar mediated Cd0.8Zn0.2S nanocomposite and synergistic adsorptive-photocatalytic performance for pollutant removal

Developing inexpensive, eco-friendly and efficient catalysts is the key to photocatalytic removal of organic pollutants from wastewater. In this paper, a novel pre-treatment activated shaddock peel biochar mediated hexagonal Cd0.8Zn0.2S composite photocatalyst (CZS/BC) was fabricated by hydrothermal method and comprehensively characterized. The photocatalytic performance was assessed by degradation of Rhodamine B (RhB) in aqueous solution under visible light irradiation. Compared with the pristine Cd0.8Zn0.2S (CZS), the doping of shaddock peel biochar (BC) not only significantly reduces the band gap energy (Eg) of the CZS, but also significantly improves the adsorption and photocatalytic performance. Under the synergistic action of adsorption and photocatalysis, the optimal CZS/BC-0.3 sample exhibited the best removal performance, and could almost completely eliminate RhB pollutant within 50min with good stability, possessing great application potential in practical environmental remediation. The removal efficiency was 6.4 folds higher than pristine CZS. Studies on photocatalytic mechanism showed that photocatalysis was mainly predominated by •O2- and h+ induced pathways, and the enhancement of photocatalytic performance can be attributed to the formation of hexagonal CZS, with biochar as an electron bridge and trap, the photogenerated carrier can be separated more effectively, thus enhancing the photocatalytic performance. This work provides a new idea for constructing new composite photocatalysts using BC as electron transport bridge.

One‐Step Synthesis of CdS/S‐Doped G‐C3N4 Composite Catalyst with Promoted Photocatalytic Hydrogen Peroxide Production Ability

AbstractH2O2 is recognized as one of the most significant chemicals, with the extensive applications across various fields. This study presents the in situ synthesis of CdS/S‐doped g‐C3N4 composite photocatalysts (CdS/CNS) via a simple one‐step thermal polymerization method by using thiourea and cadmium nitrate as precursors. The synthesized materials were characterized by using XRD, N2 adsorption, UV–vis, XPS, TEM, ESR, EIS, and PL analysis. Experimental results have indicated that the H2O2 production rate on CdS/CNS composite photocatalyst was 4.2 times higher than that of single CNS under visible light illumination, as well as the commendable catalytic stability. The formed photocatalytic system effectively reduced the recombination rate of photo‐generated electron‐hole pairs, promoted the response range of visible light, and enhanced the specific surface area of the catalyst. A preliminary discussion on potential reaction mechanisms was also provided.

Removal of tetracycline using an ultrastable Pt-decorated-BNCB photocatalyst under efficient solar-driven conditions

The pursuit of optimizing the photocatalytic performance of the novel perovskite-like Bi4NbO8X materials remains a vibrant area of research. In this paper, we report the successful synthesis of the Bi4Nb4O8Cl0.935Br0.065 (BNCB) composite photocatalyst, loaded with Pt nanoparticles, utilizing a combination of solid-state reaction and sodium borohydride reduction methods. Notably, the surface plasmon resonance (SPR) effect exhibited by Pt broadened the spectral response range, while the Schottky junction formed at the Pt/BNCB interface significantly accelerated the separation of photogenerated electron-hole pairs and facilitated the swift migration of photogenerated electrons towards Pt. Experimental outcomes underscore the superior photocatalytic degradation efficacy of the Pt/BNCB composite towards tetracycline (TC), achieving a degradation rate of up to 67%, significantly outperforming pure BNCB. Pt/BNCB exhibits excellent photocatalytic degradation and excellent stability in various pH and ionic environments. Collectively, this work presents a novel approach for designing highly efficient and stable perovskite-type photocatalytic materials, holding immense potential for applications in environmental remediation.

Hydrothermal synthesis of bismuth cluster-modified covalent triazine framework composite photocatalysts with effective performance in selective C[sbnd]C bond cleavage of lignin

With regard to the low production of aromatic monomers generated from renewable resources, improving the selective CC bond cleavage in lignin could be the solution. Here, a novel CTF-Bi cluster photocatalyst was firstly prepared by hydrothermal method. A series of Bi/CTF composite photocatalysts varying in Bi cluster content were synthesized using confined growth techniques. CB-3 with a Bi addition of 0.075 g exhibited superior photocatalytic performance, achieving a high depolymerization rate of 78.4 % for lignin model compound, and benzoic acid, benzaldehyde, and phenyl formate were the three main products with the yield of 65.2 %, 81.4 %, and 52.6 %, respectively. Mechanistic studies demonstrated that the localized surface plasmon resonance (LSPR) could suppress the reconjunction of photogenerated electrons and holes, thus improving the photocatalytic efficiency. In addition, the conduction band (CB) and valence band (VB) positions of the photocatalyst affected the selective CC bond cleavage via influencing the production of free radicals. This research offers a novel approach for the selective depolymerization of lignin, which further improved depolymerization efficiency and product selectivity, contributing to advancements in both academic research and practical biomass conversion.

Mitigation of membrane fouling in dye wastewater using a ternary WO3/CNT/ZnO composite photocatalytic membrane

The membrane filtration has been widely utilized in the water reclamation due to its simplicity in operation and outstanding separation performance. Nevertheless, the membrane filtration always suffers from the fouling issue which deteriorate the permeability of membrane. This study targeted to diminish the membrane fouling using a photocatalytic membrane. A ternary tungsten trioxide/carbon nanotube/zinc oxide (WO3/CNT/ZnO) composite photocatalyst was applied to form a ternary WO3/CNT/ZnO composite photocatalytic membrane via a wet processing technique. The highest efficiency to photodegrade methylene blue (MB) were obtained using the M5 ternary composite photocatalytic membrane. The presence of CNT and WO3 intensifies the photocatalysis in the ternary photocatalytic membrane to degrade MB. The ternary composite photocatalyst in membrane form displayed a competitive effectiveness in degrading MB when compared to particle form. The ternary composite photocatalytic membrane demonstrated a decreased permeation flux, accompanied by an increased rejection toward the MB when increasing the loading of ternary composite photocatalyst in the photocatalytic membrane. The analysis on the antifouling behaviour of the ternary composite photocatalytic membrane showed that approximately 95% of flux recovery ratio (Rfr) and 5% of irreversible fouling ratio (Rif) were obtained.

One-step hydrothermal fabrication of AgInS2/SnIn4S8 nanocomposite with enhanced visible-light-activated photocatalytic activity

In this experiment, AgInS2/SnIn4S8 materials were prepared via one-step hydrothermal method using silver chloride, the indium trichloride, stannic chloride and thioacetamide as source of silver, indium, tin and sulfur sources, respectively. The structure, content and optical property of the as-synthesized AgInS2/SnIn4S8 nanocomposite were investigated by powder Xray diffraction, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy. The ratio of AgInS2 to SnIn4S8 was optimized. When the molar amount of AgInS2 to SnIn4S8 is 0.6, AgInS2/SnIn4S8 composite photocatalyst shows the highest photocatalytic activity for degrading 2-nitrophenol (2NP) due to large absorption range and visible-light response. AgInS2/SnIn4S8 composites not only can degrade 2NP and tetracycline, but also had good mineralization efficiency for pharmaceutical industry wastewater.

Hollow core-shell heterojunction TAPB-COF@ZnIn2S4 as highly efficient photocatalysts for carbon dioxide reduction.

The conversion of carbon dioxide (CO2) into carbon-neutral fuels using solar energy is crucial for achieving energy sustainability. However, the high carrier charge recombination and low CO2 adsorption capacity of the photocatalysts present significant challenges. In this paper, a TAPB-COF@ZnIn2S4-30 (TAPB-COFZ-30) heterojunction photocatalyst was constructed by in situ growth of ZnIn2S4 (ZIS) on a hollow covalent organic framework (HCOF) with a hollow core-shell structure for CO2 to CO conversion. Both experimental studies and theoretical calculations indicate that the construction of heterojunctions improves the efficiency of carrier separation and utilisation in photocatalysis. The yield of photoreduction of CO2 to CO by the TAPB-COFZ-30 heterojunction photocatalyst reached 2895.94 μmol g-1 with high selectivity (95.75%). This study provides a feasible strategy for constructing highly active core-shell composite photocatalysts to optimize CO2 reduction.

Enhanced photocatalytic activity of SnS2 quantum dot modified Sn3O4 nanosheet composite photocatalysts for wastewater treatment applications

The construction of heterojunction is a practical way to boost the separation of photogenerated carriers and photocatalytic activity of single photocatalyst. In this paper, a novel SnS2 quantum dots/Sn3O4 nanosheets (SS/SO) heterojunction was successfully constructed by an in-situ solvothermal method with the aid of ultrasonic exfoliation, where the SnS2 quantum dots were successfully loaded on Sn3O4 nanosheets to form a close contact interface. The prepared SS/SO heterojunction presented much enhanced visible-light photocatalytic degradation of methyl orange (MO) and the reduction of chromium (Cr(VI)) compared with SnS2 quantum dots and Sn3O4. Especially, SS/SO-2 sample showed the best degradation performance of 98.16% for methyl orange (MO) in 24min, and its rate constant was 0.1494min-1, which was 15.42 and 49.87 times higher than those of pure Sn3O4 (0.0097min-1) and SnS2 (0.0030min-1), respectively. The performance for MO degradation was also much superior to some recently reported photocatalysts. In addition, the reduction efficiency of Cr(VI) could reach to 96.22% at 105min for SS/SO-2. The uniform distribution of SnS2 quantum dots and the synergistic effects of SnS2 and Sn3O4 effectively separated the photogenerated charge carriers, resulting in the superior photocatalytic performance of the SO/SS composites. The photoreaction mechanism was also carefully investigated. Parallel experiment and LC-MS were applied to investigate the degradation pathways and intermediates of MO. The construction of SnS2/Sn3O4 heterojunction will lay the foundation for the development of new visible photocatalysts and the efficient removal of pollutants such as dyes and heavy metals Cr (VI) from wastewater.

Silver (Ag) doped graphitic carbon nitride (g-C3N4)/biochar composite photocatalyst for improved photocatalytic degradation of ciprofloxacin (CIP)

Silver (Ag) doped graphitic carbon nitride (g-C3N4)/biochar composite photocatalyst for improved photocatalytic degradation of ciprofloxacin (CIP)

The well-designed wollastonite-ZnIn2S4 composite photocatalysts for efficient hydrogen production

The well-designed wollastonite-ZnIn2S4 composite photocatalysts for efficient hydrogen production

AgIO4 nanoparticles decorated on SrTiO3 microspheres as a novel Z-scheme composite photocatalyst for efficient solar-driven degradation of cefixime

The presence of antibiotics in water bodies poses severe environmental and health risks, necessitating the development of efficient and sustainable remediation technologies. In this context, photocatalysis emerged as a promising approach, leveraging light energy to degrade organic pollutants. This study introduced a novel Z-scheme SrTiO3/AgIO4 composite synthesized via a solvothermal-sonochemical route, which aimed to enhance the photocatalytic degradation of cefixime under simulated sunlight. Characterization techniques such as field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS) and transient photocurrent response (TPR) were employed to elucidate the physicochemical and optoelectronic properties of the as-synthesized composite. The SrTiO3/AgIO4 composite degraded 73.8% cefixime in 120 min, which was remarkably higher compared to its individual components. The enhanced photoactivity was credited to the synergistic interplay of both semiconductors within the Z-scheme heterojunction, which promoted effective charge separation and reduced electron-hole pair recombination.

Intermarrying MOF Glass and Lead Halide Perovskites for Artificial Photosynthesis.

The development of efficient artificial photosynthesis systems is crucial for sustainable chemical production, as they mimic natural processes to convert solar energy into chemical products, thereby addressing both energy and environmental challenges. The main bottlenecks in current research include fabricating highly selective, stable, and scalable catalysts, as well as effectively harnessing the full spectrum of light, particularly the low-energy, long-wavelength portion. Herein, we report a novel composite photocatalyst system based on lead halide perovskites embedded in functionalized MOF glass. The construction of a well-defined interface between the light-harvesting perovskite and stable Rh single-atom-containing MOF glass mimics the functions of photosystem I (PS I). This facilitates efficient photoinduced electron generation under visible light and subsequent electron transfer for coenzyme (NADH) regeneration with high selectivity. The regenerated NADH can then be consumed by immobilized enzymes for CO2 reduction, realizing the artificial photosynthesis process for formic acid generation. This work also elucidates the interactions and optoelectronic responses between MOF glass and perovskites, offering insights into the design and fabrication of nanocomposite photocatalysts for other advanced chemical syntheses.

MXene-based composite photocatalysts for efficient degradation of antibiotics in wastewater

MXene-based (nano)materials have recently emerged as promising solutions for antibiotic photodegradation from aquatic environments, yet they are limited by scalability, stability, and selectivity challenges in practical settings. We formulated Fe2O3-SiO2/MXene ternary nano-photocomposites via coupled wet impregnation and sonochemistry approach for optimised tetracycline (TC) removal (the second most used antibiotic worldwide) from water using response surface methodology-central composite design (RSM-CCD). The photocatalysts containing various loading of Fe2O3/SiO2 (5–45 wt%) on the MXene with a range of calcination temperatures (300–600 °C) via RSM optimisation were synthesised, characterised regarding crystallinity properties, surface morphology, binding energy, and light absorption capability, and analysed for TC degradation efficiency. The 25FeS/MX-450 composite among all samples demonstrated a superior efficiency in TC photocatalytic removal (98%) under optimised conditions (TC degradation: 39.75 mg/L, time: 68.28 min, pH: 5.57, catalyst dosage: 0.75 g/L). The developed surface area, with a reduced band gap due to FeS nanoparticles incorporation with improved light absorption within the visible spectrum, played a crucial role in the 25FeS/MX-450 heterostructure matrix, enhancing photogenerated carriers’ separation and transportation capabilities. The tetracycline photoreduction mechanism involved electron transfer from FeS to the surface of MXene, engaging with O2 to produce •O2−, attributed to the high electron mobility of MXene. Our findings for such nano-photocomposites materials can underscore the considerable potential of MXene-based nanomaterials for pharmaceutical removal from waterways.

Ru Metalloligands Participate in the Construction of POM@MOF for Enhancing the Visible Photoinduced Baeyer-Villiger Oxidation Reaction.

Directed synthesis of high-efficiency visible photoinduced Baeyer-Villiger oxidation catalysts is of primary significance. Here, the isopolymolybdate anion [β-Mo8O26]4- is for the first time encapsulated with the photosensitive metalloligand [Ru(bpy)2(H2dcbpy)]2+ (bpy = 2,2'-bipyridine; H2dcbpy = 2,2'-bipyridine-5,5'-dicarboxylic acid) to synthesize polyoxometalate@metal-organic frameworks, {(CdDMF)2[Ru(bpy)2(dcbpy)]3([β-Mo8O26])}·5DMF (Ru-Mo8). The composite photocatalyst Ru-Mo8 not only has a light absorption of 700 nm but also shortens the photogenerated electron transfer distances and accelerates charge and proton transfer. Ru-Mo8 can perform the Baeyer-Villiger oxidation with high selectivity and up to 96.7% yield under visible light (λ > 400 nm) irradiation. The turnover number and turnover frequency of the reaction were computed to be 967 and 548 h-1, respectively, and the apparent quantum yield was 6.84% by 425 nm. Simultaneously, the radical mechanism of Baeyer-Villiger oxidation of Ru-Mo8 in the O2/benzaldehyde system under visible light (λ > 400 nm) irradiation was proposed.

Multichromophoric Triad and g-C3N4 Composite as Efficient Heterogeneous Photocatalyst for Oxidative Amidation of Aldehydes.

In this work, we have synthesized a multichromophoric light-harvesting antenna, namely, triad, consisting of naphthalene monoimide (NMI) and perylene monoimide (PMI) chromophores. Triad was adsorbed onto polymeric graphitic carbon nitride (g-C3N4) to form triad/g-C3N4 composite, utilized as a photocatalyst for oxidative amidation reaction. This composite photocatalyst demonstrated enhanced photocatalytic activity for the conversion of a variety of aldehydes to amides, leading up to 82% product yield compared to only g-C3N4 or only triad as photocatalysts. This study highlights the potential of heterogeneous photocatalyst based on metal-free multichromophoric systems for visible-light-driven amide bond formation through an environmentally benign approach.

Effect of Calcination-Induced Oxidation on the Photocatalytic H2 Production Performance of Cubic Cu2O/CuO Composite Photocatalysts

This study explores the H2 production performance of CuO/Cu2O with different morphology (nanocubes) synthesized by different methods using different sacrificial reagent (lactic acid), compared with the other three reported CuO/Cu2O photocatalysts used for H2 production. A cubic Cu2O photocatalyst was prepared using a hydrothermal method. It was then calcined at a certain temperature to form a cubic Cu2O/CuO composite photocatalyst. XRD, TEM, and XPS spectra confirmed the successful synthesis of cubic Cu2O/CuO composite photocatalysts by calcination-induced oxidation at a certain temperature. As the calcination temperature increases, the crystal phase of the photocatalyst changes from Cu2O to Cu2O/CuO and then to CuO. The effects of calcination-induced oxidation on morphology, light absorption, the separation of photoexcited carriers, and the H2 production activity of photocatalysts were studied. EPR spectra were monitored to analyze the oxygen vacancies in different samples. Mott–Schottky and Tauc plots were utilized to establish the band structure of the composite photocatalyst. Cu2O/CuO is a type II photocatalyst with a heterogeneous structure that helps to improve electron–hole separation efficiency. The H2 production efficiency of Cu2O/CuO composite photocatalyst reaches 11,888 μmol h−1g−1, 1.6 times that of Cu2O. The formation of the Cu2O/CuO heterojunction leads to enhanced light absorption, charge separation, and hydrogen production activity.

Sustainable Removal of Phenol Dye-Containing Wastewater by Composite Incorporating ZnFe2O4/Nanocellulose Photocatalysts

The escalating issue of phenol-containing wastewater necessitates the development of efficient and sustainable treatment methods. In this context, we present a novel composite photocatalyst comprising ZnFe2O4 (ZFO) nanoparticles supported on nanocellulose (NC), aimed at addressing this environmental challenge. The synthesis involved a facile hydrothermal method followed by the impregnation of ZFO nanoparticles onto the NC matrix. The morphology and structure of ZFO, NC, and ZFO/NC were investigated by TEM, SEM-EDX, UV–vis, FT-IR, XRD, and XPS analyses. ZFO, as a weakly magnetic semiconductor catalytic material, was utilized in photocatalytic experiments under magnetic field conditions. By controlling the electron spin states through the magnetic field, electron–hole recombination was suppressed, resulting in improved photocatalytic performance. The results demonstrated that 43% and 76% degradation was achieved after 120 min of irradiation due to ZFO and 0.5ZFO/NC treatment. Furthermore, the composite 0.5ZFO/NC demonstrated the highest photocatalytic efficiency, showing promising recyclability by maintaining its activity after three cycles of use. This study underscores the potential of the ZFO/NC composite for sustainable wastewater treatment, offering a promising avenue for environmental remediation.

Integrating Ni(OH)2 Nanoparticles on CdS for Efficient Noble-Metal-Free Photocatalytic H2 Evolution.

Photocatalytic hydrogen evolution using inexhaustible clean solar energy is considered as a promising strategy. In order to build an efficient photocatalytic hydrogen production system to satisfy the demands of practical applications, it is of great significance to design photocatalysts that offer high activity, low cost, and high stability. Herein, a series of cheap CdS/Ni(OH)2 composite photocatalysts were designed and synthesized using the hydrothermal method. The introduction of a Ni(OH)2 cocatalyst multiplied the reactive active site of cadmium sulfide and promoted the transfer of photoinduced electrons in a semiconductor. Therefore, CdS/Ni(OH)2 composites demonstrate significantly better photocatalytic performance, and the hydrogen production rate of an optimal CdS/5%Ni(OH)2 composite is 6.9 times higher than that of blank CdS. Furthermore, the stability test also showed that CdS/Ni(OH)2 had good stability. This study aims to serve as a rewarding reference for the development of high-performance composite photocatalysts.

Photocatalytic Estrogen Degradation by the Composite of Tin Oxide Fine Particles and Graphene-like Carbon Nitride.

This study investigates whether 17β-estradiol (E2), a natural estrogen and one of the endocrine-disrupting chemicals responsible for water pollution, can be oxidatively decomposed under simulated solar light using a composite of tin oxide nanoparticles and graphene-like carbon nitride (g-CN) as a photocatalyst. The composite photocatalyst was prepared by heating a mixture of urea and tin acetate. FT-IR measurements revealed that g-CN possesses structural units similar to g-C3N4, a well-studied graphite-like carbon nitride. However, unlike g-C3N4, sharp diffraction lines were not observed in the XRD diffraction pattern of g-CN, indicating lower crystallinity. Elemental analysis showed that g-CN is slightly nitrogen-rich compared to g-C3N4, and UV-vis measurements indicated that the band gap of g-CN is slightly smaller than that of g-C3N4. The presence of tin in the composite of tin oxide and g-CN was clearly confirmed by XPS, although no sharp diffraction peaks were observed in the XRD patterns, suggesting the presence of microcrystals. Furthermore, FE-SEM observations did not reveal large tin oxide crystals, although EDS mapping indicated the presence of tin oxide. It was found that the prepared tin oxide and g-CN composites function effectively as photocatalysts for degrading E2 under simulated solar light. The degradation rate constant was evaluated to be k = 3.34 (0.14) × 10-2 min-1. Peroxide ion radicals were detected in ESR measurements from the irradiated solution, suggesting that peroxide ion radicals are generated through oxygen photoreduction as the counter-reaction of the oxidative decomposition of E2.