High Photocatalytic Activity Research Articles

Ce4+/Ce3+ redox effect-promoted UiO-66(Ce)/BiOBr heterojunction for enhancement photoreduction CO2 under visible light

Significant differences in the separation efficiency of electrons and holes have the potential to impact the performance of photocatalytic reduction. The objective of this study was to fabricate a BiOBr/UiO-66(Ce) type II heterostructure with the intention of improving the photocatalytic reduction activity. The cycling of Ce4+/Ce3+ within the UiO-66(Ce) structure consumed the electrons and holes, facilitating the separation of photogenerated carriers. BiOBr/UiO-66(Ce) composite demonstrated exceptional visible-light photocatalytic reduction of carbon dioxide. The highest photocatalytic activity was achieved at 2 % mass of UiO-66(Ce), which the carbon monoxide yield was 20.4 µmol·g−1·h−1. The photocatalytic activity of the BiOBr/UiO-66(Ce) composites was 11.08 times higher than BiOBr (1.84 µmol·g−1·h−1). These findings provide new insights into the use of UiO-66(Ce) as a co-catalyst in the photocatalytic reduction of CO.

ZnO/Zn3(PO4)2/CeO2 photocatalysts formed on zinc by plasma electrolytic oxidation

ZnO/Zn3(PO4)2 coatings doped with CeO2 particles for use in photocatalytic degradation of methyl orange (MO) were created by plasma electrolytic oxidation of zinc in a phosphate alkaline electrolyte (PAE) with CeO2 particle concentrations of up to 1.5 g/L. The CeO2 particle content in ZnO/Zn3(PO4)2 coatings was determined by the concentration of CeO2 particles in the PAE. Extensive research was conducted on coating morphology, chemical and phase compositions, and light-harvesting properties. The photocatalytic activity (PA) of ZnO/Zn3(PO4)2/CeO2 coatings was higher than ZnO/Zn3(PO4)2. The PA of ZnO/Zn3(PO4)2/CeO2 coatings strongly depends on the amount of CeO2 particles in PAE, and the highest PA was observed for ZnO/Zn3(PO4)2/CeO2 coating formed in PAE by adding 0.75 g/L of CeO2 particles. The higher PA of ZnO/Zn3(PO4)2/CeO2 compared to ZnO/Zn3(PO4)2 is due to a lower photogenerated electron/hole recombination. The photocatalytic degradation of MO followed a pseudo-first order kinetic model and the reaction constant of the most photoactive ZnO/Zn3(PO4)2/CeO2 coating was increased about twofold compared to the ZnO/Zn3(PO4)2 coating. After 6 hours of irradiation, the PA for ZnO/Zn3(PO4)2 and the most photocatalytically active ZnO/Zn3(PO4)2/CeO2 was about 70% and 98%, respectively. A mechanism for the photodegradation of MO with the ZnO/Zn3(PO4)2/CeO2 photocatalyst was also proposed.

Multifunctional superhydrophobic sugarcane bagasse capable of efficiently separating oil-water mixtures and degrading MB

Biodegradable and low-cost superhydrophobic absorption materials are still urgently required for the removal of organic compounds from sewage. In this study, sugarcane bagasse (SCB), an abundant and readily available byproduct from sugarcane industries, was used as substrate to fabricate the superhydrophobic adsorbent through a facile dip-coating technique. Firstly, β-FeOOH particles were in-situ grown on the SCB surface, which was further decorated with SiO2 particles. Next, the modified SCB were coated with benzoxazine based on cardanol and dodecylamine (CD) followed by a thermal curing to obtain a superhydrophobic SCB (PC-D/β-FeOOH@SiO2/SCB) with a water contact angle (WCA) of 154°. PC-D/β-FeOOH@SiO2/SCB not only exhibited excellent oil absorption capacities in the range of 11.8 to 22.6 g/g for various organic solvents and oils, but also could successfully separate immiscible oil-water mixtures and emulsions with a separation efficiency of over 99.1 %. After 30 cycles of use, the absorption capacity of the modified SCB only displayed a slight decrease and its separation efficiencies for immiscible oil-water mixture, water-in-oil and oil-in-water emulsions are all more than 99.2 %, meanwhile, all these repeatedly used SCB still maintained a superhydrophobicity, demonstrating an outstanding reusability. Moreover, the WCA of PC-D/β-FeOOH@SiO2/SCB was still higher than 150o after 48 h of immersion in HCl, NaOH and NaCl solutions, exhibiting a satisfactory chemical stability. Besides, the prepared SCB also possessed a high photocatalytic degradation activity to methylene blue. Therefore, this work not only provides a sustainable and cheap superhydrophobic absorbent for wastewater treatment, but also presents a route for the better utilization of SCB.

Plasmon and N-vacancy synergistically enhanced tubular carbon nitride-based S-scheme heterojunction photocatalyst with one stone five birds function: Pathways, DFT calculation and mechanism insight

From the perspectives of innovation and broad-spectrum, tubular carbon nitride-based photocatalyst, viz., Ag/AgI/g-C3N4 S-scheme heterojunction photocatalyst, with enhancement of nitrogen vacancy and localized surface plasmon resonance (LSPR) effect is reasonably devised and manufactured via combining hydrothermal, calcination and photo-reduction techniques. The optimal specimen displays high photocatalytic activity in removal of dyes (such as crystalline violet, 100.00 %/60 min), antibiotics (such as levofloxacin, 88.72 %/50 min) and Cr6+ (100.00 %, 30 min), photocatalytic hydrogen evolution (1023.3 μmol h−1 g−1) and H2O2 generation (866.2 μmol h−1 g−1), achieving broad-spectrum natures, viz., realizing the function of “one stone five birds”. The broad-spectrum natures are attributed to the synergisms of nitrogen vacancy, LSPR effect of Ag, hollow tube structure and S-scheme heterojunction, which facilitate the separation and migration of photo-generated carriers and inject “hot electrons” generated by Ag into the conduction band of Ag/AgI/g-C3N4, increase the specific surface area and broaden the spectral response range. Further, the degraded intermediates of crystalline violet and levofloxacin and possible degradation pathways are rationally advanced by the aid of LCMS spectra, and synergistically enhanced photocatalytic mechanism of Ag/AgI/g-C3N4 hollow tube S-scheme heterojunction is confirmed based upon a series of sound experiments, fs-TA spectra, in-situ XPS and DFT calculation, etc.

Adsorption‐photocatalysis for methylene blue dye removal by novel Fe‐MOFs through defect engineering

AbstractIn recent years, metal–organic frameworks (MOFs) have attracted much attention in environmental pollution control. However, most MOFs still have problems such as low utilization of visible light and easy recombination of photogenerated electrons and holes. In this study, novel defective Fe‐MOFs with appropriate structural defects were prepared by solvothermal method and used to remove methylene blue (MB) in aqueous phase through adsorption and photocatalysis. Defective Fe‐MOFs have Fe content as high as 10.31% with specific surface area of 40.95 m2/g, which is beneficial for both dye adsorption and photocatalytic process. Defective Fe‐MOFs have spindle‐like structures with sizes ranging from 40 nm to 100 nm and an average size of 69.1 nm, as well as some irregularly shaped nanoparticles. Irregular stacking of these two kinds of structure makes Fe‐MOFs appropriate structural defects, large specific surface area, and mesoporous structure. Kinetics and isotherms of dye adsorption process are consistent with pseudo‐first‐order kinetic model and Freundlich isotherm model, respectively. Defective Fe‐MOFs can absorb MB dye rapidly, reaching adsorption equilibrium within 60 min. Dye adsorption process is endothermic, spontaneous, and entropy‐increasing process. After 180 min visible light illumination, dye photocatalytic efficiency of the defective Fe‐MOFs reaches 97.56% in the condition of MB concentration as high as 30 mg/L. Consequently, defective Fe‐MOFs with appropriate structural defects, porous structure, high Fe‐O content, and strong electron‐donating amino groups have huge potential applications in removing organic dyes from the aqueous solution by a green and environmentally friendly way due to their high dye adsorption and dye photocatalytic activity.

Selective adsorption-photocatalytic synergistic breakdown of sulfamethazine in milk using loaded molecularly imprinted Ag3PO4/TiO2 films

To remove antibiotics from milk effectively, molecularly imprinted Ag3PO4/TiO2 photocatalysts (MAT) were prepared using sulfamethazine (SMZ) as a template and butyl titanate as a functional monomer. Molecularly imprinted Ag3PO4/TiO2 films (MATs) were constructed using quartz glass tubes as the carrier. The morphology and structure of MAT, the properties and mechanism of degradation of SMZ by MATs, and the nutrition and safety of milk were evaluated. The results showed that MAT formed obvious imprinted cavities and n–p-type heterojunctions. Moreover, MATs exhibited the highest degradation rate (82.4 %) of SMZ, an enhanced selectivity factor α (3.98), and adsorption capacity Q (8.47 mg/g), which did not alter protein, fat, or acidity values in milk and no photocatalyst residue was detected. The high photocatalytic activity and selectivity of MATs for SMZ were mainly attributed to the presence of imprinted holes that matched the template molecules, the large specific surface area, the formation of n–p-type heterostructures, and Z-type charge transfer.

H2O2-assisted Bi3NbO7 loaded on porous carbon for enhancing the photocatalytic degradation of tetracycline

Bi3NbO7 loaded on porous carbon (BNO/PC) composite materials has been prepared by the in-suit sol-gel method. The photocatalytic efficacy of the BNO/PC composite has been evaluated by degrading tetracycline (TC) in an environment of visible light and hydrogen peroxide. Moreover, the relevant influencing factors of TC degradation efficiency have been explored through a series of condition optimization experiments. UV–vis DRS and PL tests showed that the loading on porous carbon significantly broadens the visible light response range of the catalyst and improves the separation efficiency of photogenerated carriers. Compared with the bare BNO, the specific surface area and average pore diameter of the BNO/PC composite material increased greatly. The optimal sample of 35 % BNO/PC exhibited outstanding visible light response ability and excellent charge separation efficiency. The “cata + H2O2+vis” system had the highest photocatalytic activity, with TC degradation reaching 86.9 % after 60 min of visible light illumination. The addition of hydrogen peroxide (H2O2) promoted the formation of more powerful active substances. Following this, a mechanism for photocatalytic degradation has been proposed.

Eco-Friendly TiO2 Nanoparticles: Harnessing Aloe Vera for Superior Photocatalytic Degradation of Methylene Blue

In recent years, the contamination of aquatic environments by organic chemicals, including dyes such as methylene blue (MB), Congo red, and crystal violet, has become an increasing concern, as has their treatment. In this work, titanium dioxide nanoparticles (TiO2 NPs) were studied for their photocatalytic performance by measuring the degradation of MB under UV light. TiO2 NPs were synthesized using two synthetic processes optimized in this study: a green method, namely leveraging the natural properties of Aloe vera leaf extract; and a conventional approach. The resulting NPs were thoroughly characterized using X-rays Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET), UV–Vis and ζ-potential analysis. The TiO2 NPs synthesized by the green method demonstrated a degradation efficiency of (50 ± 3)% after 180 minutes, which was significantly higher than the (16 ± 3)% achieved by NPs synthesized through the conventional route. Moreover, the reaction rate constant for the green-synthesized TiO2 NPs was found to be approximately five times greater than that of the conventionally synthesized NPs. These results open up a new scenario in the pollution removal strategy research, using resources accessible in nature to synthesize NPs with high photocatalytic activity, which could also be useful for other applications, such as hydrogen production.

Benzobisoxazole-based covalent organic frameworks for efficient photocatalytic oxidation

Covalent organic frameworks, as an emerging porous crystalline material, have attracted significant interest in heterogeneous photocatalysis, due to their tunable structure, large specific surface area, high chemical stability, and extendable π-conjugated skeleton. In this study, 4,4′-(2,6-dimethylbenzo[1,2-d:4,5-d′]bis(oxazolyl)-4,8-diyl)dianiline (OZDL) and benzene-1,3,5-tricarboxaldehyde (BTCA) were utilized to construct 2D covalent organic frameworks OZBT-COF through aldehyde-amine polycondensation reaction under solvothermal conditions. Considering the high crystallinity, chemical stability, and outstanding photophysical properties, the benzobisoxazole-containing OZBT-COF was further employed as a photocatalyst for the synthesis of the benzothiazole derivatives and the oxidation of N-substituted tetrahydroisoquinolines. The catalyst system exhibited high photocatalytic activity, moderate substrate applicability, excellent stability and recyclability. The suitable band gap, efficient separation of photogenerated charge carriers, and enhancing mass transport inside the porous catalyst could be contributed to superior photocatalytic performance. This work provides valuable insights into the structure–function correlations of COFs-based photocatalysts, and further demonstrates promising opportunities for developing COF photocatalysts with practical applications.

Hydrothermally synthesized hierarchical Pom-Pom-like gadolinium modified tungsten oxide reinforced with rGO for annihilation of acetylsalicylic acid and crystal violet

Herein, novel hierarchical Gd@WO3 pom-pom-like microstructures have been prepared through the hydrothermal method and combined with RGO sheets (denoted as RGO/Gd@WO3). The synthesized materials, along with their analogs, were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), Mott-Schottky, current-voltage (I-V), electrochemical impedance spectroscopy (EIS), and optical analyses. The unique morphology of pom-pom-like microstructures allowed better interaction with pollutant molecules. Rare earth element (Gd3+) ions act as trapping species for photo-generated electrons and prolong the life span of reactive oxygen species (ROS). The high conductivity and flexible nature of RGO sheets provided fast transport of active species and provided stability to the photocatalytic material. To test the photocatalytic efficiency of RGO/Gd@WO3, crystal violet (CV) and acetylsalicylic acid (ASA) were used as model pollutants. Under a mimetic light source, RGO/Gd@WO3 exhibited maximum photodegradation of 98.8 % and 84 % for CV and ASA within 120 min of irradiation, respectively. Photocurrent, Mott-Schottky, and EIS experiments proved the production, effective separation, and transmission of photo-active species in the presence of RGO/Gd@WO3 as compared to Gd@WO3 and WO3. Given the electrochemical testing and optical analysis, the photocatalytic mechanism is anticipated for the high photocatalytic activity of RGO/Gd@WO3. The novel RGO/Gd@WO3 photocatalyst proved to be a superior photocatalytic material for the photodegradation of organic pollutants.

Solvothermal synthesis of a flower-like double Z-scheme PANI/Bi2Sn2O7/BiOBr/Ti photoanode and its performance in photocatalytic fuel cell

Photocatalytic fuel cell (PFC) provides a new method to degrade organic pollutants and recover their energy simultaneously. In this work, a novel flower-like hierarchical photoanode (PANI/Bi2Sn2O7/BiOBr/Ti) was synthesized by solvothermal method and assembled with Cu cathode to form a PFC for rhodamine B (RhB) degradation and simultaneous power generation. The crystal structure, chemical composition, and morphology of the photoanode was characterized by a variety of analysis techniques. The photocatalytic activity of the ternary hierarchical composite photoanode was superior to that of single and binary composite photoanodes. Its maximum photocurrent density, maximum power density, degradation rate and FF were 0.241 mA·cm−2, 21.52μW·cm−2, 92.97 % (90 min) and 0.18, respectively. In addition, it still maintains high photocatalytic activity after five consecutive uses. Based on the analysis results of transient photocurrent (i-t), EIS, DRS spectrum, M-S curve and free radical capture experiments, the improvement of photocatalytic performance of PANI/Bi2Sn2O7/BiOBr/Ti photoanode is attributed to the formation of dual Z-scheme heterojunction between PANI and BiOBr and between Bi2Sn2O7 and BiOBr, which realizes the rapid separation and transfer of electron-hole pairs, and retains the strong oxidation of holes in VB of BiOBr and the strong reduction of electrons in LUMO of PANI and CB of Bi2Sn2O7. This study provides a new research idea for the design and construction of high efficiency photoanode in PFC system.

Fabrication and characterization of hierarchically macroporous Al2O3 ceramic supported ZnO/ZnS photocatalyst

Hierarchically macroporous Al2O3 ceramic carriers were prepared by direct-foaming combined gel-freezing method. ZnO/ZnS photocatalyst was loaded on the porous carrier through hydrothermal method. The effects of solid content, polyvinyl alcohol content, stirring speed, and sintering temperature on the pore structure, porosity, and compressive strength of the porous carrier were investigated. The pore forming mechanism was also studied. The morphology of ZnO/ZnS photocatalyst was adjusted by changing the pH value during hydrothermal process. The results show that the porous ceramic contains four different sizes of pores, spherical pore, through pore, unidirectional pore, and interstitial pore. The pore structure and strength can be regulated through optimizing process parameters. The porosity and compressive strength of porous carrier prepared with 1.2 % PVA content, 22 % solid content, 1500 r/min stirring speed and 1500 °C sintering temperature are 89.4 % and 1.45 MPa, respectively, which is suitable to be used as the photocatalyst carrier. When the pH value is 10, the size and distribution of ZnO/ZnS photocatalyst are matched with the pore structure of porous carrier. The supported ZnO/ZnS has high photocatalytic activity and good reusability.

Enhanced photocatalytic hydrogen evolution via yolk–heteroshell TiO2@TiO2/SiO2 nanoreactor with confined Pt nanoparticles

The upper limit of photocatalytic efficiency is largely determined by the light-harvesting capability of a semiconductor. To address this challenge, we developed a yolk-heteroshell TiO2@TiO2/SiO2 (T@T/S) nanoreactor, leveraging a novel design based on an in-depth understanding and innovative utilization of light-matter interactions. The T@T/S nanoreactor significantly enhances solar light capture and utilization efficiency through total internal reflection mechanisms facilitated by the heterogeneous shell. This heteroshell, consisting of an outer SiO2 shell an inner monolayer of TiO2 nanoparticles, maximizes light confinement due to the different refractive indices of SiO2 and TiO2, while also minimizing mass transfer resistance due to the thin inner shell layer. These unique structural features result in high photocatalytic activity under simulated solar light. Additionally, we successfully applied a “ship-in-a-bottle” strategy for the confined growth of platinum nanoparticles within T@T/S nanoreactor. The Pt0.5-T@T/S nanoreactors demonstrated excellent hydrogen production, achieving a hydrogen evolution rate of 24.43 mmol g−1h−1 under simulated sunlight and an apparent quantum efficiency (AQE) of 7.8 % at 350 nm. This study highlights the importance of nano-engineered designs in optimizing semiconductor photocatalysts and shows the significant potential of our approach for sustainable energy conversion and environmental protection.

Achieving high photocatalytic NOx removal activity using a Bi/BiOBr/TiO2 composite photocatalyst

Fossil fuel combustion generates nitrogen oxides (NO + NO2 = NOx), which pose threats to the environment and human health. Although commercial products containing titanium dioxide (TiO2) can remedy NOx pollution by photocatalysis, they only function in the ultraviolet (UV). On the other hand, bismuth oxybromide (BiOBr) is active in the visible. BiOBr is stable, affordable, and non-toxic, making it an appealing alternative. In addition, nanoparticulate Bi metal can further enhance visible light absorption through its surface plasmon properties and charge carrier lifetime by spatially separating charge. In this study, to enhance the visible-light activity of TiO2-based photocatalysts for NOx pollution, a composite of Bi-decorated BiOBr/TiO2 was synthesised using a solvothermal method across varying the Ti/Bi atomic ratio (0.2, 2.2, 4.4, and 6.6), and synthesis duration (6h, 12h, and 18h). The photocatalytic performance of the synthesised composites for NO gas removal was investigated using an adapted ISO method (22197–1:2016). Analysis showed that the preferential growth of the (010) crystal facet in BiOBr and the presence of Bi metal both play an important role in the superior photocatalytic activity seen in our Bi-decorated BiOBr/TiO2 composite. The composites were characterised using X-ray diffraction (XRD), attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR), high-resolution scanning electron microscopy (HR-SEM), UV–Vis diffuse reflectance (DRS) spectroscopy, transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Brunauer-Emmett-Teller (BET) analysis, thermogravimetric analysis (TGA), and diffuse reflectance transient absorption spectroscopy (DR-TAS). Our research shows that the Bi/BiOBr–TiO2 composite synthesised through a 12h solvothermal method with a Ti/Bi atomic ratio of 4.4 exhibits the highest photocatalytic performance towards both NO and NO2 oxidation; with 32.8% and 54.9% NO removal and 15.1% and 29.5% NO2 under visible and UV lamps, respectively.

Photocatalyst for Antibiotics Degradation by In Situ Growth of Direct Z-Type Bi2S3/Bi4Ti3O12 Heterojunction.

Effective removal of antibiotics from aqueous solutions has emerged as a hot research topic in wastewater treatment. Photocatalytic degradation of antibiotics is one of the most effective methods to reduce ecological damage and environmental pollution. In this work, a novel photocatalyst consisting of Z-type heterojunction Bi2S3/Bi4Ti3O12 (BS/BTO) with visible light responses was prepared by an in situ growth method, and the obtained material was used for the degradation of tetracycline hydrochloride (TC). The best performing photocatalyst was BS/BTO-2, which exhibited high photocatalytic activity. The rates of TC degradation reached 97.9% within 40 min of illumination. The photocatalyst demonstrated a high stability and reproducibility even after 5 cycles. Electron spin resonance (EPR) tests and quenching experiments established that ·O2- and h+ were the main species responsible for the elimination of TC. On the basis of theoretical calculations and experimental data, a possible mechanism for the photocatalytic degradation of TC has been proposed. The heterojunction structure, which effectively increases the visible light absorption range and decreases the compounding efficiency of photogenerated electrons and holes, is principally responsible for the photocatalytic performance of BS/BTO. Additionally, liquid chromatography-mass spectrometry (LC-MS) was utilized to investigate the formation and degradation of reaction intermediates. The nontoxicity of the solution after tetracycline degradation was verified by cultivating wheat seeds. This work offers guidance for bismuth-based photocatalysts in the field of sustainable wastewater treatments.

Visible light-driven selective oxidative transformation of vicinal diols using ZnS-based photocatalyst in the presence of molecular oxygen

The heterogeneous photocatalysis for the oxidative cleavage of C–C bond is significant to the transformation of biomass feedstock. In this work, a heterojunction photocatalyst based on the conductor ZnS and C3N4 (CN) material is prepared and employed in the aerobic oxidative cleavage reaction of vicinal diol under visible light irradiation. As a result, it is found that 3ZnS/CN catalyst obtained by a mechanical grinding method shows a high photocatalytic activity. In the photocatalytic oxidative cleavage process of 1-phenyl-1,2-glycol, more than 98.7% conversion of substrate with a 96.2% selectivity of benzaldehyde was attained using O2 as oxidant. In addition, the photocatalyst recycling experiments exhibited that the 3ZnS/CN catalyst still kept a good activity and stability even after being recycled for 5 times. Finally, the active reaction intermediates were investigated by the control experiments and the relative electron paramagnetic resonance (EPR) detection. According to the obtained results and photocatalytic principle, the mechanism for the selective oxidative transformatioin of 1-phenyl-1,2-glycol has been proposed. It gives a promising approach for the catalytic utilization of biomass-based lignin and cellulose.

Decorating Cu2O with Copper Metal (Cu) through Facile Electrochemical Deposition for Methylene Blue Degradation

Cuprous oxide (Cu2O) thin film was decorated with copper metal (Cu) by the simple electrochemical deposition method. This study was motivated to improve the role of Cu as a co-catalyst due to the narrow band gap energy of known photocatalyst Cu2O. Cu was electrodeposited on Cu2O thin film with a substrate of indium tin oxide (ITO) at a voltage of -0.3V and a temperature of 60 °C in CuSO4 (pH 10) under a magnetic stirrer. The structure, phase, and morphology of Cu2O/Cu were characterised by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The electrocatalytic performance of Cu2O/Cu was recorded using linear sweep voltammetry and electrochemical impedance spectroscopy. XRD and SEM results show Cu was successfully deposited covering Cu2O. The current density of Cu2O/Cu increased by 2.7041 mA/cm2 confirming the lower charge current resistance of 2.48 kΩ. The Cu-decorated Cu2O demonstrated an improved photocatalytic activity, as shown by the increase of MB degradation from 46.33% to 50.87%. It was believed from characterisations that Cu deposition leads to more dense carriers and charge transfer, hence higher photocatalytic activity towards MB degradation than bare Cu2O thin film.

P3HT/g-C3N4 composite fiber membranes for high-performance photocatalytic hydrogen evolution

As a superstar semiconducting polymer, poly(3-hexylthiophene) (P3HT) demonstrates high efficiency in carrier transport ability and wide absorption range. However, pristine P3HT exhibits minimal photocatalytic activity as a result of its short carrier transport distance and fast electron-hole recombination. Here, we strategically fabricated P3HT/g-C3N4 composites on polymethyl methacrylate (PMMA) fiber (PTCN) via electrospinning and the physicochemical properties were fully investigated. Raman spectroscopy, ultraviolet–visible (UV–Vis) absorption spectra and X-ray photoelectron spectroscopy (XPS) results demonstrated a well-defined p-n heterojunctions can be formed between P3HT and g-C3N4 molecules through π-π interaction and extended conjugated length of P3HT could be achieved by tuning the ratios of P3HT relative to g-C3N4. The presence of the heterojunctions facilitates the effective disconnection of the electron-hole pairs, resulting in a significantly enhanced photocatalytic hydrogen evolution rate of 7327 μ mol/(h·g) for the PTCN fiber membranes. This value exceeds that of P3HT fibers by 57.7 times and powder g-C3N4 by 6.8 times, respectively. The high photocatalytic hydrogen production activity of P3HT/g-C3N4 fiber membrane expands the application of P3HT. More importantly, these results indicate that the construction of heterojunction fiber materials is a promising approach for improving the photocatalytic ability of conjugated semiconducting polymers.

Photo-deposition of AgO thin films on TiO2 substrate for (P-N) hetero-junction applications: Considering the degree of contamination

This study explored the development of photocatalytic heterostructures via the P-N junction formation between TiO2 and AgO. TiO2 thin films were fabricated on glass substrates through dip coating. Subsequently, photodeposition of AgO was achieved under sunlight irradiation using varying AgNO3 concentrations (0.5–2.5 g/L). The films were characterized using XRD, SEM, EDX, UV–vis, and water droplet tests. Samples with concentrations below 2 g/L uniquely exhibited the anatase phase, while a significant prominence of AgO was observed in the film prepared with a 2 g/L AgNO3 concentration. Silver nitrate contamination loads had a significant impact on the particle size and the overall morphological characteristics of the heterojunctions. The band gap values were 3.52 eV for the anatase substrate, whereas the band gaps of the photodeposited films decreased from 2.44 to 1.98 eV. Despite all films being hydrophilic, a rise in water droplet contact angle was observed in the heterojunctions compared to the pure TiO2. Photodegradation of methylene blue under sunlight irradiation demonstrated exceptional efficiency (>90 %) for the 2 g/L AgNO3 heterojunction in 6 hours, maintaining high photocatalytic activity over multiple cycles (>77 %). This same configuration achieved a 50 % degradation of amoxicillin within 2 hours. This investigation addresses water contamination issues while offering a straightforward production method for efficient P-N junction co-catalysts.

Improving Photocatalytic Efficiency with Titanium Dioxide Quantum Dots

Titanium dioxide quantum dots (TiO2-QDs), synthesized using a microwave-assisted method, represent a significant advancement in photocatalysis, particularly in the treatment of environmental pollutants. This study focuses on TiO2-QDs synthesized at 200°C for a duration of 5 minutes, using titanium butoxide as a precursor. Characterization through TEM, XRD, PL, and UV-Vis-DRS analyses revealed uniform quantum dots with an average size of 5.28 nm, a bandgap energy of 3.22 eV, and a crystalline anatase phase, indicative of high photocatalytic activity. Notably, these TiO2-QDs demonstrated exceptional performance in degrading methylene blue (MB) in water, achieving a remarkable treatment efficiency of 97.6% in 120 min, significantly outperforming both conventional titanium dioxide nanoparticles and commercial titanium dioxide materials. The reaction conditions were evaluated based on factors such as catalyst dose, initial MB concentration, and pH. The results indicate that optimal degradation efficiency of MB was achieved at a pH of 7, with a catalyst dose of 0.15 g/L and at a low MB concentration. The efficiency slightly decreased to 94.5% after five reuse cycles, emphasizing its significant reusability and stability. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).