Film Photocatalyst Research Articles

Polyhydroxykanoate-Assisted Photocatalytic TiO2 Films for Hydrogen Production.

The photocatalytic production of hydrogen using biopolymer-immobilized titanium dioxide (TiO2) is an innovative and sustainable approach to renewable energy generation. TiO2, a well-known photocatalyst, benefits from immobilization on biopolymers due to its environmental friendliness, abundance, and biodegradability. In another way, to boost the efficiency of TiO2, its surface properties can be modified by incorporating co-catalysts like platinum (Pt) to improve charge separation. In this work, the surface of commercial TiO2 PC500 was modified with Pt nanoparticles (Pt1%@PC500) and then immobilized on glass surfaces using polyhydroxyalkanoate biopolymer poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBH). The as-prepared immobilized Pt-modified TiO2 photocatalysts were fully characterized using various physicochemical techniques. The photocatalytic activity of the photocatalyst film was investigated for photocatalytic hydrogen production through water reduction using ethanol as a sacrificial donor. The impact of the film preparation conditions, e.g., PHBH concentration, PHBH:catalyst ratio, and temperature, on activity and stability was studied in detail. The application of biopolymer PHBH as a binder provides a green alternative to conventional immobilization methods, and with the application of PHBH, a stable and active photocatalyst film that showed lower activity compared to that of the suspended photocatalyst but good recyclability in six runs was prepared. A long-term photocatalytic hydrogen production experiment was carried out. In 98 h of operation, 12 mmol of hydrogen was produced in three consecutive runs with a PHBH/Pt1%@PC500 film having an area of ∼5.3 cm2. A significantly lower hydrogen productivity was observed after the first run, possibly due to a change in film structure, but thereafter, the productivity remained almost constant for the second and third runs. Hydrogen was the main product in the gas phase (90%), but carbon dioxide (4-5%) and methane (4-5%) were obtained as important byproducts. The byproducts are a consequence of the use of the sacrificial reagent ethanol. The results of the film performance are very promising, with regard to large-scale continuous hydrogen production.

Enhanced Photocatalytic Hydrogen Production Activity Driven by TiO2/(MoP/CdS): Insights from Powder Particles to Thin Films.

Transitioning from powder photocatalysts to thin film photocatalysts is one of the necessary steps toward industrializing photocatalytic hydrogen production. Herein, we reported the integration of non-noble metal cocatalyst MoP decorated with TiO2 and CdS, forming TiO2/(MoP/CdS) for ultraviolet-visible light utilization. The designed powder TiO2/(MoP/CdS) composites achieved a superior hydrogen production rate of 42.2 mmol g-1 h-1, which is 30.1 times that of TiO2/CdS, performing the highest activity among the TiO2-CdS-based composite photocatalysts. Moreover, we fabricated a thin film from TiO2/(MoP/CdS) powder, which exhibited comparable photocatalytic activity for hydrogen production, achieving 35.5 mmol g-1 h-1 and maintaining long-term stability for 150 h. The outstanding performance was attributed to the ability of the TiO2/(MoP/CdS) composite photocatalysts to absorb both visible and ultraviolet light. Additionally, the heterojunction formed between TiO2 and CdS also played a significant role in the overall photocatalyst activity. This cost-effective catalyst holds promise for future large-scale industrial applications.

Rational Engineering of Nanostructured NiS/GO/PVA for Efficient Photocatalytic Degradation of Organic Pollutants

A novel nanocomposite film synthesized from an inexpensive and easily accessible polymer such as poly (vinyl alcohol) (PVA), which is coated with nickel sulfide (NiS) and graphene oxide (GO), was obtained from used drinking-water bottles. The produced coated film was examined as a potential photocatalyst film for wastewater treatment promotion in a batch system for the removal of methylene blue (MB) and tetracycline (TC) antibiotics. The experimental results show that the presence of GO significantly increases the photocatalytic efficiency of NiS, and the MB and TC degradation results proved that the incorporation of GO with NiS led to a more than one-and-a-half-fold increase in the removal percentage in comparison with the NiS/PVA-coated film. After 30 min of illumination using GO/NiS/PVA-coated film, the removal efficiency reached 86% for MB and 64% for TC. The photodegradation kinetic rate followed the pseudo-first-order rate. Furthermore, the response surface methodology (RSM) model was utilized to study and optimize several operating parameters. The ideal circumstances to achieve 91% elimination of MB are 12 mg L−1 MB initial concentration, two lamps, and an illumination time of 15 min; however, to achieve 85% TC removal, 11 mg L−1 TC initial concentration, two lamps, and a 45 min illumination time should be used. The fabricated nanocomposite photocatalyst film seems to have promise for use in water purification systems.

Variable valence I3−/I− ionic bridge assisting CuI nanoparticle/BiOI nanosheet S-scheme photocatalyst with hydrophobic surface for boosting CO2 conversion with 100 % CO selectivity

The photocatalyst film, composed of tetragonal BiOI nanosheets and cubic phase CuI nanoparticles, was synthesized on the FTO substrate by a simple electro-deposition method. The orderly crisscrossed nanosheet structure caused exterior hydrophobic property, resisting the excess H2O molecules and further inhibiting the competitive H2O reduction process. The novel BiOI/CuI catalyst exhibited excellent photocatalytic ability of CO2 reduction into CO with 100 % selectivity in H2O vapor. Typically, the optimal 150BiOI/CuI photocatalyst exhibited CO yield of 7237.65 μmol/cm2 after 11 h of simulated sunlight illumination, achieving quantum efficiency of 2.5 % at 380 nm. The excellent performance of the BiOI/CuI composite film in photocatalytic CO2 reduction can be attributed to the construction of hydrophobic surface and S-scheme heterojunction with I3−/I− redox mediator, as confirmed by the in-situ XPS, hole injection test and cyclic voltammetry results. This study lays the groundwork for employing highly efficient iodide-based photocatalysts in gas-liquid-solid triphase catalytic systems.

Construction of broad-spectrum photocatalyst films through interface engineering: Orchestrating Bi nanoparticles in TiO2/BiVO4 Z-scheme heterojunctions

We successfully synthesized three-layered photocatalysts by modifying Bi nanoparticles on TiO2/BiVO4 bilayer composite films through a sol-gel process and sputtering. When exposed to ambient air, the surface of the prepared Bi nanoparticles oxidizes to form an amorphous ultra-thin Bi2O3 out layer. Under light exposure, this layer is reduced to metallic Bi, thanks to the band alignment between the Bi nanoparticles and TiO2/BiVO4 Z-scheme composite. The addition of Bi nanoparticles in the composite films improves visible-light absorption by the surface plasmon resonance (SPR), which contributes to the hot electron and enhances the photocatalytic characteristics. By constructing effective TiO2/BiVO4 Z-scheme heterostructures to facilitate photoinduced electron-hole pair separation and prevent recombination, Bi nanoparticles can efficiently capture photons and enhance the photocatalytic efficiency of semiconductors through the SPR effect. Optimizing the content of Bi nanoparticles decorated on the TiO2/BiVO4 Z-scheme composite film is a promising approach for designing a highly efficient photocatalyst, as evidenced by the performance of photoelectrochemical properties and RhB photodegradation ability.

Defects induced SnOx-TiO2 nanocomposite thin films for improved visible light driven photocatalysis and photoelectrochemical applications

Advanced oxidative removal of organic pollutants from water bodies using nanoparticles of metal oxide photocatalysts is a concurrent hot topic. In the present study, SnOx-TiO2 heterogeneous nanocomposite thin film photocatalysts have been synthesized using SnO and TiO2 precursors by binder-free doctor blade technique. X-ray diffraction was used to confirm the presence of anatase TiO2 as a major phase at elevated temperatures. Raman spectra analysis confirmed phase transformation and defect induction. X-ray photoelectron spectroscopy was utilized to determine the purity and chemical condition of the synthesized thin films. The porous nature of the thin film surface was observed using field emission scanning electron microscopy. UV–Vis-NIR spectroscopy results showed a reduction of bandgap from 3 eV to 2.6 eV with enhanced light absorption. The superior oxygen evolution reaction, redox nature and charge carrier generation were demonstrated using photo-electrochemical techniques. Improved photoresponse of the photocatalysts was observed using chrono-amperometry technique. The superior visible light-driven photocatalytic activity of the samples was demonstrated utilizing cationic and anionic model pollutant dyes. The reusability of the catalyst is ensured through successive photodecomposition processes. These results show a facile fabrication of defects induced heterogenous nanocomposite photocatalyst thin films with improved visible light activity.

Magnetically-induced enhancement of photocatalytic dye decomposition in ferroelectric Hf0.5Zr0.5O2 films

The film photocatalyst is easily recycled and has attracted the widely research interesting. Here the ferroelectric Hf0.5Zr0·5O2(HZO) thin film synthesized through the atomic layer deposition (ALD) method is used as a photocatalyst for the rhodamine B (RhB) dye decomposition under visible light irradiation. The photocatalytic RhB dye decomposition performances with or without an external magnetic field excitation provided by a commercial NdFeB magnet are experimentally characterized. With the increasing of the external direct-current (DC) magnetic field from 0 to 3000 Gs, the photocatalytic RhB dye decomposition ratio by HZO film obviously increases from 87.20 % to 98.17 %, which is attributed to the enhanced separation of the photo-induced positive and negative carrier due to the magnetic Lorentz effect. The magnetically-induced enhancement of photocatalysis in the ferroelectric HZO film, provides a method with these advantages of simple external excitation method, remarkable promotion effect and friendly-environment to enhance the dye decomposition ratio, and is potential in the practical application of photocatalytic dye wastewater treatment through harvesting the clean solar energy in future.

Enhancement photocatalytic activity of CeO2 infused CA@Gelatin nanocomposites for the degradation of organic dyes under UV-light irradiation

In the present study, facile 100 % recoverable handpicked CeO2/CA@GEL (CA; Cellulose acetate, GEL; Gelatine) nanocomposite thin film photocatalyst were successfully synthesized by simple solution cast method. The efficacy of the CeO2/CA@GEL was tested against the photodegradation of organic dyes viz Crystal violet (CV) and Rhodamine-B (RhB) under visible light irradiation. The CeO2/CA@GEL exhibited excellent photocatalytic activity, durability and utmost 80.52 % (CV) and 82.65 % (RhB) degradation of the dye solution was achieved within 60 min. The CeO2/CA@GEL showed the excellent degradation efficiency compared to pure CeO2 Nanoparticles. The reactive oxidative species involved in the photocatalytic reaction is superoxide radical anion (O2 radical) and OH radical under visible light irradiation by trapping experiments. The 100 % recovery of the photocatalyst was achieved by simple handpicking process and stable unto its 3rd usage.

Novel nanostructure approach for antibiotic decomposition in a spinning disc photocatalytic reactor

Conventional wastewater treatment processes are often unable to remove antibiotics with resistant compounds and low biological degradation. The need for advanced and sustainable technologies to remove antibiotics from water sources seems essential. In this regard, the effectiveness of a spinning disc photocatalytic reactor (SDPR) equipped with a visible light-activated Fe3O4@SiO2-NH2@CuO/ZnO core–shell (FSNCZ CS) thin film photocatalyst was investigated for the decomposition of amoxicillin (AMX), a representative antibiotic. Various characterization techniques, such as TEM, FESEM, EDX, AFM, XRD, and UV–Vis-DRS, were employed to study the surface morphology, optoelectronic properties, and nanostructure of the FSNCZ CS. Key operating parameters such as irradiation time, pH, initial AMX concentration, rotational speed, and solution flow rate were fine-tuned for optimization. The results indicated that the highest AMX decomposition (98.7%) was attained under optimal conditions of 60 min of irradiation time, a rotational speed of 350 rpm, a solution flow rate of 0.9 L/min, pH of 5, and an initial AMX concentration of 20 mg/L. Moreover, during the 60 min irradiation time, more than 69.95% of chemical oxygen demand and 61.2% of total organic carbon were removed. After the photocatalytic decomposition of AMX, there is a substantial increase in the average oxidation state and carbon oxidation state in SDPR from 1.33 to 1.94 and 3.2, respectively. Active species tests confirmed that ·OH and ·O2− played a dominant role in AMX decomposition. The developed SDPR, which incorporates a reusable and robust FSNCZ CS photocatalyst, demonstrates promising potential for the decomposition of organic compounds.

Optimizing Conductive Polymer Bulk Structure: Influence of Polymerization Temperature on Photocatalytic Performance for Sustainable Hydrogen Production

The influence of the polymerization temperature upon the bulk‐structure‐doped conductive polymer polyaniline (emeraldine‐salt, PANI) on the semiconducting, optical, and electrical properties of the photocatalyst is investigated. When the B‐PANI polymerization temperature increases from 5 to 60 °C, the crystallinity and conductivity of Pt/N‐TiO2/B‐PANI (PNT/B‐PANI) decreases. To rectify the problems of recycling convenience and secondary pollution, this study combines a photocatalyst and a porous polystyrene film for sustainable hydrogen production. The photocatalytic performance of the polystyrene/PNT/B‐PANI‐5 (PS/PNT/B‐PANI‐5) photocatalyst film (27 047 μmol h−1 g−1) under simulated sunlight irradiation is enhanced by a factor of up to 1.6 compared to that of PS/PNT. Therefore, the PS/PNT/B‐PANI photocatalyst film is a visible‐light photocatalyst which is a promising candidate for enhancing photocatalytic recycling convenience.

Optimizing photocatalytic degradation: SnO2-PVC thin film catalyst for efficient removal of acridine orange

Industrial wastewater containing hazardous organic pollutants is an emerging global issue demands efficient treatment methods. The semiconductor-mediated photodegradation has emerged as a promising solution, which gaining increased interest. This study focuses on photocatalytic degradation of Acridine Orange using thin film catalyst composed of PVC immobilized with nano SnO2. The photocatalytic efficiency of the prepared catalyst was evaluated through various experiments, and the operational parameters such as irradiation source, initial dye concentration, pH, and co-occurring ions were investigated. The catalyst demonstrated superior dye removal under UV radiation at 254 nm. The impact of pH revealed maximal degradation at pH 11. Moreover, the study explored the influence of co-occurring ions, indicating their quenching effect on the degradation process. Kinetic analysis revealed a concentration-dependent degradation rate which aligns with the kinetic model of Langmuir−Hinshelwood. The reusability of the SnO2-thin film photocatalyst demonstrated sustained activity over multiple cycles. The findings highlight the potential of SnO2-PVC thin film as a photocatalyst for dye removal, emphasizing the importance of optimizing operational parameters for enhanced efficiency.

Preparation and characterization of TiO2 photocatalyst films and their application for preservation of Agaricus bisporus in combination with blue-violet LEDs

This study aims to prepare and characterize non-metallic nitrogen-modified titanium dioxide (N–TiO2), film and expand its photocatalytic excitation wavelength to the visible blue-violet region. The film uses corn starch as a carrier. It is combined with blue-violet LED light to explore the effect of this combination on the quality of Agaricus bisporus during storage. This study found that the mechanical properties and hydrophobicity of the corn starch film with nano-TiO2 added were improved; the effect of adding N–TiO2 was more pronounced; the tensile strength increased by 65% while the water contact angle increased by 11%. In the application of A. bisporus storage, the film combined with blue-violet LED light can slow down the loss of moisture, reduce the respiratory rate, delay the appearance of the respiratory peak, and maintain the color and hardness of A. bisporus. After 15 d of storage, compared to the control group, the hardness decreased by 69%, browning index (BI) increased by 221%, the CS-N group hardness decreased by only 23%, and the BI increased by 89%. Under blue-violet LED light, the accumulation of secondary metabolites in A. bisporus increased, and the polyphenol content also showed an increasing trend during storage.

Large-Area Conductive MOF Ultrathin Film Controllably Integrating Dinuclear-Metal Sites and Photosensitizers to Boost Photocatalytic CO2 Reduction with H2O as an Electron Donor.

Owing to the electrical conductivity and periodic porosity, conductive metal-organic framework (cMOF) ultrathin films open new perspectives to photocatalysis. The space-selective assembly of catalytic sites and photosensitizers in/on cMOF is favorable for promoting the separation of photogenerated carriers and mass transfer. However, the controllable integration of functional units into the cMOF film is rarely reported. Herein, via the synergistic effect of steric hindrance and an electrostatic-driven strategy, the dinuclear-metal molecular catalysts (DMC) and perovskite (PVK) quantum dot photosensitizers were immobilized into channels and onto the surface of cMOF ultrathin films, respectively, affording [DMC@cMOF]-PVK film photocatalysts. In this unique heterostructure, cMOF not only facilitated the charge transfer from PVK to DMC but also guaranteed mass transfer. Using H2O as an electron donor, [DMC@cMOF]-PVK realized a 133.36 μmol·g-1·h-1 CO yield in photocatalytic CO2 reduction, much higher than PVK and DMC-PVK. Owing to the excellent light transmission of films, multilayers of [DMC@cMOF]-PVK were integrated to increase the CO yield per unit area, and the 10-layer device realized a 1115.92 μmol·m-2 CO yield in 4 h, which was 8-fold higher than that of powder counterpart. This work not only lightens the development of cMOF-based composite films but also paves a novel avenue for an ultrathin film photocatalyst.

Liquid metal-embraced photoactive films for artificial photosynthesis

The practical applications of solar-driven water splitting pivot on significant advances that enable scalable production of robust photoactive films. Here, we propose a proof-of-concept for fabricating robust photoactive films by a particle-implanting technique (PiP) which embeds semiconductor photoabsorbers in the liquid metal. The strong semiconductor/metal interaction enables resulting films efficient collection of photogenerated charges and superior photoactivity. A photoanode of liquid-metal embraced BiVO4 can stably operate over 120 h and retain ~ 70% of activity when scaled from 1 to 64 cm2. Furthermore, a Z-scheme photocatalyst film of liquid-metal embraced BiVO4 and Rh-doped SrTiO3 particles can drive overall water splitting under visible light, delivering an activity 2.9 times higher than that of the control film with gold support and a 110 h stability. These results demonstrate the advantages of the PiP technique in constructing robust and efficient photoactive films for artificial photosynthesis.

Pt-Black-Modified (Hemi)spherical AFM Sensors: In Situ Imaging of Light-Driven Hydrogen Peroxide Evolution.

In this work, we present (hemi)spherical atomic force microscopy (AFM) sensors for the detection of hydrogen peroxide. Platinum-black (Pt-B) was electrodeposited onto conductive colloidal AFM probes or directly at recessed microelectrodes located at the end of a tipless cantilever, resulting in electrocatalytically active cantilever-based sensors that have a small geometric area but, due to the porosity of the films, exhibit a large electroactive surface area. Focused ion beam-scanning electron microscopy tomography revealed the porous 3D structure of the deposited Pt-B. Given the accurate positioning capability of AFM, these probes are suitable for local in situ sensing of hydrogen peroxide and at the same time can be used for (electrochemical) force spectroscopy measurements. Detection limits for hydrogen peroxide in the nanomolar range (LOD = 68 ± 7 nM) were obtained. Stability test and first in situ proof-of-principle experiments to achieve the electrochemical imaging of hydrogen peroxide generated at a microelectrode and at photocatalytically active structured poly(heptazine imide) films are demonstrated. Force spectroscopic data of the photocatalyst films were recorded in ambient conditions, in solution, and by applying a potential, which demonstrates the versatility of these novel Pt-B-modified spherical AFM probes.

Characterization and photocatalytic activity of TiO2 thin films prepared by sol-gel method for NOx degradation

Titanium dioxide (TiO2) thin film photocatalysts for the elimination of nitrogen oxides (NOx) were prepared by the dip-coating process using the sol–gel method. To prepare the sols, titanium (IV) butoxide (Ti(OBu)4), diethanolamine (DEA), butanol, and HCl were chosen. The TiO2 coatings were prepared using sols with varying volume ratios of Ti(OBu)4:DEA:Butanol. Additionally, three withdrawal speeds from the sol were employed. Subsequently, the TiO2 thin films were sintered at 500 and 700 °C. The obtained thin films were characterized using SEM to determine thickness, AFM to determine roughness, and the Step 500 platform for the adhesion test. NOx was found to be efficiently eliminated by TiO2 thin film photocatalyst. It is possible to obtain a TiO2 coating that is capable of degrading 300 ppb of NO in real time under specific conditions: a relative humidity of 30 %, a UV intensity of 20 W/m2, a gas flow rate of 1 dm3/min.

Correction: Sein–EY marvels: effortless elegance in crafting flexible film photocatalysts for formic acid production from CO2 and cyclization of thioamides in the air’s embrace

Correction for ‘Sein–EY marvels: effortless elegance in crafting flexible film photocatalysts for formic acid production from CO2 and cyclization of thioamides in the air’s embrace’ by Rehana Shahin et al., New J. Chem., 2024, https://doi.org/10.1039/d4nj00531g.

Sein–EY marvels: effortless elegance in crafting flexible film photocatalysts for formic acid production from CO2 and cyclization of thioamides in the air's embrace

Carbon dioxide reduction together with aerobic oxidative cyclization using eosin Y-based light-harvesting photocatalysts remains a key challenge.

Synergistic effects of Fe and Ag doping on the structural and optical properties of a TiO2 thin film: a dual function platform for hydrogen generation and dye degradation.

The global population is increasing at an alarming pace, leading to a rapid surge in industrialization and concomitant environmental degradation. In light of the present circumstances, it is crucial to find sustainable solutions to mitigate pollution and ensure a safe and clean environment for the present and future society. One promising solution is photocatalysis, which utilizes solar energy to address environmental issues while providing a renewable and sustainable energy source. Herein, a TiO2-based multi-layer thin film photocatalyst was developed, and its hydrogen generation and Rhodamine 6G dye degradation properties were analysed. As TiO2 undergoes excitation in the UV region, in order to shift the absorbance towards the visible region, bandgap engineering was performed with Fe and Ag doping. As a consequence, the band gap effectively reduces, and Fe and Ag doping result in the least gap energies measuring 2.7 eV and 2.85 eV, respectively. DFT band structure study was performed, which shows the presence of additional electronic states that lie in the conduction and valence energy bands of TiO2 owing to the doping of elements. Additionally, the effect of the number of thin film layers on photocatalysis was investigated. To confirm the presence of structural distortions and oxygen vacancies, different characterizations were performed.

ZnIn2S4 thin films with hierarchical porosity for photocatalysis

A solution-based route towards hierarchically porous ZnIn2S4 photocatalyst films combining macropores (300 nm), and nanopores (1.6 nm) is presented.