Effects of fluorine on photocatalysis

Manipulating the H2O2 Reactivity on Pristine Anatase TiO2 with Various Surface Features and Implications in Oxidation Reactions

Anatase TiO2 is commonly used as a catalyst/support in reactions involving H2O2, yet the understanding of interactions between common TiO2 surfaces and H2O2 remains limited. Herein, we synthesized well-defined TiO2 crystallites with (101), (001), and fluorine-modified (001) [F-(001)] surfaces to examine how surface features, including the arrangement of five-coordinated Ti (Ti5c) sites and the presence of fluorine, influence H2O2 activation. Our findings reveal that these surface features significantly affect the physiochemical properties of adsorbed H2O2. Specifically, fluorine on the F-(001) surface introduces an additional hydrogen bond to the Ti5c-peroxo species, altering the electronic structure of H2O2 compared to those with the (101) and (001) surfaces. Using cyclohexene as a probe substrate, we successfully distinguished the reactivities of the Ti5c-peroxo species. The activity of those on the F-(001) surface was significantly higher than the activity of those on the (001) surface, while the (101) surface showed negligible oxidation activity. These insights can guide the design of TiO2-based catalysts for H2O2-related reactions.

Construction of Covalent Triazine Frameworks with Electronic Donor-Acceptor System for Efficient Photocatalytic C-H Hydroxylation of Imidazole[1,2-α]Pyridine Derivatives

Covalent triazine frameworks (CTFs) are promising heterogeneous photocatalyst candidates owing to their excellent stability, conjugacy, and tunability. In this study, a series of CTFs decorated with different substituents (H, MeO, and F) were synthesised and utilised as photocatalysts for C-H activation reactions. The corresponding optoelectronic properties could be precisely regulated by the electronic effects of different substituents in the nanopore channels of the CTFs; these CTFs were effective photocatalysts for C-H activation in organic synthesis due to their unique structures and optoelectronic properties. Methoxy-substituted CTF (MeO-CTF) exhibited extraordinary catalytic performance and reusability in C-H functionalization by constructing an electronic donor-acceptor system, achieving the highest yield in the photocatalytic C3-H hydroxylation of 2-phenylimidazole[1,2-α]pyridine. This strategy provides a new scaffold for the rational design of CTFs as efficient photocatalysts for organic synthesis.

Electron repulsion tuned electronic structure of TiO2 by fluorination for efficient and selective photocatalytic ammonia generation

The photocatalytic conversion of nitrogen into high-value ammonia products holds tremendous potential in the global nitrogen cycle. However, the activation of N2 and competition of hydrogen evolution limit the improvement of nitrogen fixation performance. In this study, we developed a fluorinated TiO2 (F-TiO2) using a hydrothermal-annealing method. The incorporation of F dopants not only enhances the adsorption and activation of N2 through electronic structure regulation, but also facilitates an in situ increase in active sites via the electron repulsion effect between F and Ti atoms. In addition, the presence of F on the surface effectively improved the nitrogen supply problem and optimized the nitrogen fixation selectivity for its hydrophobic modulation. The NH3 yield of the F-TiO2 photocatalyst reached 63.8 μmol h-1 g-1, which was 8.5 times higher than that of pure TiO2. And the selectivity experiment showed that the electronic ratio of NH3 to H2 production reached 0.890. This research offers valuable insights for the design of highly efficient and selective nitrogen-fixing photocatalysts.

Preparation and Application of a Novel S-Scheme Nanoheterojunction Photocatalyst (LaNi0.6Fe0.4O3/g-C3N4)

Rapid recombination of photogenerated electrons and holes affects the performance of a semiconductor device and limits the efficiency of photocatalytic water splitting for hydrogen production. The use of an S-scheme nanoscale heterojunction catalyst for the separation of photogenerated charge carriers is a feasible approach to achieve high-efficiency photocatalytic hydrogen evolution. Therefore, we synthesized a three-dimensional S-scheme nanoscale heterojunction catalyst (LaNi0.6Fe0.4O3/g-C3N4) and investigated its activity in photocatalytic water splitting. An analysis of the band structure (XPS, UPS, and Mott-Schottky) indicated effective interfacial charge transfer in an S-scheme nanoscale heterojunction composed of two n-type semiconductors. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectroscopy confirmed that the light-induced charge transfer followed the S-scheme mechanism. Based on the capture test (EPR) of •OH free radicals, it can be seen that the enhanced activity is attributed to the S-scheme carrier migration mechanism in heterojunction, which promotes the rapid adsorption of H+ by the abundant amino sites in g-C3N4, thus effectively generating H2. The 2D/2D LaNi0.6Fe0.4O3/g-C3N4 heterojunction has a good interface and produces a built-in electric field, improving the separation of e- and h+ while increasing the oxygen vacancy. The synergistic effect of the heterostructure and oxygen vacancy makes the photocatalyst significantly better than LaNi0.6Fe0.4O3 and g-C3N4 in visible light. The hydrogen evolution rate of the composite catalyst (LaNi0.6Fe0.4O3/g-C3N4-70 wt %) was 34.50 mmol·h-1·g-1, which was 40.6 times and 9.2 times higher than that of the catalysts (LaNiO3 and g-C3N4), respectively. After 25 h of cyclic testing, the catalyst (LaNi0.6Fe0.4O3/g-C3N4-70 wt %) composite material still exhibited excellent hydrogen evolution performance and photostability. It was confirmed that the synergistic effect between abundant active sites, enriched oxygen vacancies, and 2D/2D heterojunctions improved the photoinduced carrier separation and the light absorption efficiency of visible light. This study opens up new possibilities for the logical design of efficient photodecomposition using 2D/2D heterojunctions combined with oxygen vacancies.

Advances and future perspectives of water defluoridation by adsorption technology: A review

Fluoride contamination in water sources poses a significant challenge to human health and the environment. In recent years, adsorption technology has emerged as a promising approach for water defluoridation due to its efficiency and cost-effectiveness. This review article comprehensively explores the advances in water defluoridation through adsorption processes. Various adsorbents, including natural and synthetic materials, have been investigated for their efficacy in removing fluoride ions from water. The mechanisms underlying adsorption interactions are elucidated, shedding light on the factors influencing defluoridation efficiency. Moreover, the review outlines the current state of technology, highlighting successful case studies and field applications. Future perspectives in the field of water defluoridation by adsorption are discussed, emphasizing the need for sustainable and scalable solutions. The integration of novel materials, process optimization, and the development of hybrid technologies are proposed as pathways to address existing challenges and enhance the overall efficacy of water defluoridation. This comprehensive assessment of the advances and future directions in adsorption-based water defluoridation provides valuable insights for researchers, policymakers, and practitioners working towards ensuring safe and accessible drinking water for all.

High-Entropy Photothermal Materials

High-entropy (HE) materials, celebrated for their extraordinary chemical and physical properties, have garnered increasing attention for their broad applications across diverse disciplines. The expansive compositional range of these materials allows for nuanced tuning of their properties and innovative structural designs. Recent advances have been centered on their versatile photothermal conversion capabilities, effective across the full solar spectrum (300-2500 nm). The HE effect, coupled with hysteresis diffusion, imparts these materials with desirable thermal and chemical stability. These attributes position HE materials as a revolutionary alternative to traditional photothermal materials, signifying a transformative shift in photothermal technology. This review delivers a comprehensive summary of the current state of knowledge regarding HE photothermal materials, emphasizing the intricate relationship between their compositions, structures, light-absorbing mechanisms, and optical properties. Furthermore, the review outlines the notable advances in HE photothermal materials, emphasizing their contributions to areas, such as solar water evaporation, personal thermal management, solar thermoelectric generation, catalysis, and biomedical applications. The review culminates in presenting a roadmap that outlines prospective directions for future research in this burgeoning field, and also outlines fruitful ways to develop advanced HE photothermal materials and to expand their promising applications.

Enhanced photocatalytic performance of Bi2O2CO3/Bi4O5Br2/reduced graphene oxide Z-schemehe terojunction via a one-pot room-temperature synthesis

Bi2O2CO3(BOC)/Bi4O5Br2(BOB)/reduced graphene oxide (rGO) Z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method. Ultra-thin nanosheets of BOC and BOB were grown in situ on rGO. The formed 2D/2D direct Z-scheme heterojunction of BOC/BOB with oxygen vacancies (OVs) effectively leads to lower negative electron reduction potential of BOB as well as higher positive hole oxidation potential of BOC, showing improved reduction/oxidation ability. Particularly, rGO is an acceptor of the electrons from the conduction band of BOC. Its dual roles significantly improve the transfer performance of photo-induced charge carriers and accelerate their separation. With layered nanosheet structure, rich OVs, high specific surface area, and increased utilization efficiency of visible light, the multiple synergistic effects of BOC/BOB/rGO can achieve effective generation and separation of the electron-holes, thereby generating more •O2- and h+. The photocatalytic reduction efficiency of CO2 to CO (12.91 µmol/(g·hr)) is three times higher than that of BOC (4.18 µmol/(g·hr)). Moreover, it also achieved almost 100% removal of Rhodamine B and cyanobacterial cells within 2 hours.

Remarkable Enhancement of Photocatalytic Activity of High-Energy TiO2 Nanocrystals for NO Oxidation through Surface Defluorination

The superior photocatalytic activity of TiO2 nanocrystals with exposed high-energy (001) facets, achieved through the use of hydrofluoric acid as a shape-directing reagent, is widely reported. However, in this study, we report for the first time the detrimental effect of surface fluorination on the photoreactivity of high-energy faceted TiO2 nanocrystals towards NO oxidation (resulting in a NO removal rate of only 5.9%). This study aims to overcome this limitation by exploring surface defluorination as an effective strategy to enhance the photocatalytic oxidation of NO on TiO2 nanocrystals enclosed with (001) facets. We found that surface defluorination, achieved through either NaOH washing (resulting in an improved NO removal rate of 23.2%) or calcination (yielding an enhanced NO removal rate of 52%), leads to a large increase in the photocatalytic oxidation of NO on TiO2 nanocrystals with enclosed (001) facets. Defluorination processes stimulate charge separation, effectively retarding recombination and significantly promoting the production of reactive oxygen species, including superoxide radicals (·O2-), singlet oxygen (1O2), and hydroxyl radicals (·OH). Both in situ diffuse reflectance infrared Fourier-transform spectroscopy and density functional theory calculations confirm the higher adsorption of NO after defluorination, thus facilitating the oxidation of NO on TiO2 nanocrystals.

Sensitive sensing of Hg(II) based on lattice B and surface F co-doped CeO2: Synergies of catalysis and adsorption brought by doping site engineering

Transition metal oxides are widely used in the detection of heavy metal ions (HMIs), and the co-doping strategy that introducing a variety of different dopant atoms to modify them can obtain a better detection performance. However, there is very little research on the co-doped transition metal oxides by non-metallic elements for electrochemical detection. Herein, boron (B) and fluorine (F) co-doped CeO2 nanomaterial (BFC) is constructed to serve as the electrochemically sensitive interface for the detection of Hg(II). B and F affect the sensitivity of CeO2 to HMIs when they were introduced at different doping sites. Through a variety of characterization, it is proved that B is successfully doped into the lattice and F is doped on the surface of the material. Through the improvement of the catalytic properties and adsorption capacity of CeO2 by different doping sites, this B and F co-doped CeO2 exhibits excellent square wave anodic stripping voltammetry (SWASV) current responses to Hg(II). Both the high sensitivity of 906.99 μA μM-1 cm-2 and the low limit of detection (LOD) of 0.006 μM are satisfactory. Besides, this BFC glassy carbon electrode (GCE) also has good anti-interference property, which has been successfully used in the detection of Hg(II) in actual water. This discovery provides a useful strategy for designing a variety of non-metallic co-doped transition metal oxides to construct trace heavy metal ion-sensitive interfaces.

Advances in photothermal regulation strategies: from efficient solar heating to daytime passive cooling

Photothermal regulation concerning solar harvesting and repelling has recently attracted significant interest due to the fast-growing research focus in the areas of solar heating for evaporation, photocatalysis, motion, and electricity generation, as well as passive cooling for cooling textiles and smart buildings. The parallel development of photothermal regulation strategies through both material and system designs has further improved the overall solar utilization efficiency for heating/cooling. In this review, we will review the latest progress in photothermal regulation, including solar heating and passive cooling, and their manipulating strategies. The underlying mechanisms and criteria of highly efficient photothermal regulation in terms of optical absorption/reflection, thermal conversion, transfer, and emission properties corresponding to the extensive catalog of nanostructured materials are discussed. The rational material and structural designs with spectral selectivity for improving the photothermal regulation performance are then highlighted. We finally present the recent significant developments of applications of photothermal regulation in clean energy and environmental areas and give a brief perspective on the current challenges and future development of controlled solar energy utilization.

Synthesis of Fluoride-Substituted Layered Perovskites ZnMoO4 with an Enhanced Photocatalytic Activity

Oxyfluorides possess considerable attention for their multiple excellent properties, but the conventional high-temperature solid-state syntheses have seen bottlenecks in the synthesis of new compounds. Herein, we report a novel layered oxyfluoride ZnMoO4:F, which is prepared by a facile hydrothermal method using ZnF2 as the fluoride source. The fluoride anions are successfully introduced into the oxygen sublattice, which is confirmed by a combined analysis using XRD, STEM, and TGA techniques. The as-synthesized ZnMoO4:F has an absorption edge at around 550 nm, indicating a red shift of Eg to the visible region compared to the oxide counterpart. The layered oxyfluoride exhibits an enhanced photocatalytic active for hydrogen evolution under simulated sunlight (λ > 350 nm), and the activity of ZnMoO4:F (651.9 μmol g-1) was 2 times higher than that of ZnMoO4 (309.7 μmol g-1). Further electrochemical analysis has shown that the conduction band position plays a critical role in the high performances of ZnMoO4:F. This work sheds new light on the future design and synthesis of novel fluoride-doped materials for photocatalysis applications.

Electrochemical or Photoelectrochemical Alkenylpolyfluoroalkylation of 3-Aza-1,5-dienes: Regioselective Entry to Polyfluoroalkylated 4-Pyrrolin-2-ones

An electrochemical or photoelectrochemical regioselective polyfluoroalkylation/cyclization cascade of 3-aza-1,5-dienes with sodium fluoroalkanesulfinates is presented. This protocol proceeds with a broad substrate scope and good functional group tolerance under mild, oxidant-free, transition-metal-free, and electrolyte-free conditions to provide 3-polyfluoroalkylated 4-pyrrolin-2-ones in one step from readily available N-vinylacrylamides, and it is readily scalable to the Gram scale.

Visible-Light-Driven Photocatalytic Dehydrogenation of Alcohols on TiO2 via Ligand-to-Metal Charge Transfer for Coproduction of H2 and Aldehydes

Developing visible-light-driven photocatalysts for the catalytic dehydrogenation of organics is of great significance for sustainable solar energy utilization. Here, we first report that aromatic alcohols could be efficiently split into H₂ and aldehydes over TiO₂ under visible-light irradiation through a ligand-to-metal charge transfer (LMCT) mechanism. A series of TiO₂ catalysts with different surface contents of the hydroxyl group (-OH) have been synthesized by controlling the hydrothermal and calcination synthesis methods. An optimal H₂ production rate of 18.6 μmol h^-1 is obtained on TiO₂ synthesized from the hydrothermal method with a high content of surface -OH. Experimental characterizations and comparison studies reveal that the surface -OH markedly influences the formation of LMCT complexes and thus changes the visible-light-driven photocatalytic performance. This work is anticipated to inspire further research endeavors in the design and fabrication of visible-light-driven photocatalyst systems based on the LMCT mechanism to realize the simultaneous synthesis of clean fuel and fine chemicals.

F-doped TiO2(B)/reduced graphene for enhanced capacitive lithium-ion storage

A composite of F-doped TiO₂(B) and reduced graphene oxide (F-TiO₂(B)/rGO) was successfully synthesized via a one-step hydrothermal route. It was found that the introduction of F ions in the synthetic process has led to the uniform dispersion of TiO₂(B) on rGO nanosheets. The F ions have also been doped into the lattice of TiO₂(B), which greatly improved the conductivity of the materials. Consequently, this composite delivered a large capacity of 249.4 mA h g^-1 at 0.2 A/g. It also demonstrated a capacity of 203.1 mA h g^-1 and an excellent capacity retention of 96% after 500 cycles even at a high current density of 2 A/g.

Enhancing the eosin-yellowish dye degradation in drinking water by using TiO2 coatings co-doped with Ni and In

This work reports on the structural, morphological, and photocatalytic properties of titanium dioxide (TiO₂) and TiO₂:NiIn (T-NiIn) coatings fabricated by spin coating. The SEM images revealed coatings with average thicknesses of 3.59 and 3.37 μm for the TiO₂ and T-NiIn, respectively. EDS spectra and Raman studies confirmed the presence of TiO₂ co-doped with nickel (Ni) and indium (In) in the coatings. XRD analysis showed the anatase and rutile phases for the TiO₂ coatings, while the T-NiIn coatings presented the rutile and brookite phases. These samples were evaluated in the photocatalytic degradation of the eosin-yellowish (EY) dye. The T-NiIn coatings showed 9.1% higher effectiveness than the undoped TiO₂ coatings after 300 min under UV irradiation. Meanwhile, the T-NiIn coatings exposed to solar light removed 40% more dye than the TiO₂ coatings. Furthermore, T-NiIn coating was the most stable because its effectiveness was reduced by only 1.4% after 4 cycles of reuse. Additionally, the scavenger tests confirmed that the main oxidizing sites were the •OH^- radicals and the superoxides •O₂^-. Thus, the use of coatings based on TiO₂ co-doped with Ni and In is a feasible strategy to increase the degradation of the EY dye in drinking water.

Efficient and Stable Catalytic Hydrogen Evolution of ZrO2/CdSe-DETA Nanocomposites under Visible Light

Composite photocatalysts are crucial for photocatalytic hydrogen evolution. In this work, ZrO2/CdSe-diethylenetriamine (ZrO2/CdSe-DETA) heterojunction nanocomposites are synthesized, and efficiently and stably catalyzed hydrogen evolution under visible light. X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscope (HRTEM) confirm the formation of heterojunctions between ZrO2 (ZO) and CdSe-DETA (CS). Ultraviolet–visible spectroscopy diffuse reflectance spectra (UV-vis DRS), Mott–Schottky, and theoretical calculations confirm that the mechanism at the heterojunction of the ZrO2/CdSe-DETA (ZO/CS) nanocomposites is Type-I. Among the ZO/CS nanocomposites (ZO/CS-0.4, ZO/CS-0.6, and ZO/CS-0.8; in the nanocomposites, the mass ratio of ZO to CS is 0.1:0.0765, 0.1:0.1148, and 0.1:0.1531, respectively). ZO/CS-0.6 nanocomposite has the best photocatalytic hydrogen evolution activity (4.27 mmol g−1 h−1), which is significantly higher than ZO (trace) and CS (1.75 mmol g−1 h−1). Within four cycles, the ZO/CS-0.6 nanocomposite maintains an efficient catalytic hydrogen evolution rate. Due to the existence of the heterojunction of the composites, the photogenerated electron-hole pairs can be effectively separated, which accelerates the photocatalytic hydrogen evolution reaction and reduces the progress of photocorrosion. This work reveals the feasibility of ZO/CS nanocomposite photocatalysts for hydrogen evolution.

Existence of Ti3+ and dislocation on nanoporous CdO-TiO2 heterostructure applicable for degrading chlorophenol pollutant

This study addresses the significance of wastewater recuperation by a simple and facile treatment process known as photocatalyst technology using visible light. Titanium di-oxide (TiO₂) is the most promising photocatalyst ever since longing decades, has good activity under UV light, owing to its small band gap. Hence, TiO₂ has been modified with metal oxides for the positive response against visible light. Since this is an efficient process, the novelty has been made on nanometal oxide CdO (cadmium oxide) combined with TiO₂ to acquire the best efficiency of degrading organic chlorophenol contaminant. Initially, the composites were synthesized by sol-gel and thermal decomposition methods and investigated for their various outstanding properties. The characterized outcomes have exhibited heterostructures with reduced crystallite size from the X-ray diffraction studies. Then, the determination of nanoporous feature was recognized through HR-TEM analysis which was also detected with some dislocations. The EDX spectrum was identified the perfect elemental composition. The nitrogen adsorption-desorption equilibrium was attained that offers many pores measured with high surface area. The XPS result convinced that Ti³⁺ was accessible along with TIO₂/CdO composite. Further the absorption towards higher wavelength was obtained from UV-vis spectra. Finally, for the photocatalytic application of chlorophenol, the composite shows higher percentage of degrading efficiencies than the pristine TiO₂. The photocatalytic mechanism was discussed in detail.

Nanomaterials photocatalytic activities for waste water treatment: a review

Water is necessary for the survival of life on Earth. A wide range of pollutants has contaminated water resources in the last few decades. The presence of contaminants incredibly different dyes in waste, potable, and surface water is hazardous to environmental and human health. Different types of dyes are the principal contaminants in water that need sudden attention because of their widespread domestic and industrial use. The toxic effects of these dyes and their ability to resist traditional water treatment procedures have inspired the researcher to develop an eco-friendly method that could effectively and efficiently degrade these toxic contaminants. Here, in this review, we explored the effective and economical methods of metal-based nanomaterials photocatalytic degradation for successfully removing dyes from wastewater. This study provides a tool for protecting the environment and human health. In addition, the insights into the transformation of solar energy for photocatalytic reduction of toxic metal ions and photocatalytic degradation of dyes contaminated wastewater will open a gate for water treatment research. The mechanism of photocatalytic degradation and the parameters that affect the photocatalytic activities of various photocatalysts have also been reported.

Recent Progress of Natural Mineral Materials in Environmental Remediation

Organic contaminants, volatile organic compounds (VOCs), and heavy metals have posed long-term threats to the ecosystem and human health. Natural minerals have aroused widespread interest in the field of environmental remediation due to their unique characteristics such as rich resources, environmentally benign, and excellent photoelectric properties. This review briefly introduced the contributions of natural minerals such as sulfide minerals, oxide minerals, and oxysalt minerals in pollution control, which include organic pollution degradation, sterilization, air purification (NO VOCs oxidation), and heavy metal treatment by means of photocatalysis, Fenton catalysis, persulfate activation, and adsorption process. At last, the future challenges of natural mineral materials in pollution control are also outlooked.

Facile Preparation of Highly Active CO2 Reduction (001)TiO2/Ti3C2Tx Photocatalyst from Ti3AlC2 with Less Fluorine

To date, (001)TiO2/Ti3C2Tx hybridized photocatalyst is usually prepared through the complicated treatment of Ti3AlC2 in the presence of corrosive fluorine with a molar ratio of nF:nTi of more than 20. To reduce the use of corrosive fluorine, herein, exploiting beyond the conventional method, we report a facile synthetic method for (001)TiO2/Ti3C2Tx, elaborately using HF as both an etchant for Al elimination and a morphology control agent for the growth of (001)TiO2 nanosheets, with a sharply diminished use of fluorine (nF:nTi = 4:1) and simplified operation procedures. After optimization, the resulting (001)TiO2/Ti3C2Tx heterojunction exhibited markedly high photocatalytic activity with the CO2 reduction rate of 13.45 μmol g−1 h−1, which even surpasses that of P25 (10.95 μmol g−1 h−1), while the photoelectron selectivity to CH4 is approaching 92.84%. The superior photoactivity is interpreted as the fact that Ti3C2Tx with a lower work function induces photoinduced hole transfer and suppresses the charge recombination, thus facilitating the CO2 multi-electron reduction. This study provides a novel and simple synthesis for (001)TiO2/Ti3C2Tx towards sustainable energy transformations.

Bridging Effect of S-C Bond for Boosting Electron Transfer over Cubic Hollow CoS/g-C3N4 Heterojunction toward Photocatalytic Hydrogen Production

The construction of interfacial effects and chemical bonds between catalysts is one of the effective strategies to facilitate photogenerated electron transfer. A novel hollow cubic CoS is derived from Co-ZIF-9 and the S-C bond is successfully constructed between CoS and g-C₃N₄. The S-C bond acts as a bridge for electronic transmission, allowing the rapid transmission of photoelectron to hydrogen evolution active site in CoS. In addition, the results of electrochemical impedance spectroscopy and time-resolved photoluminescence spectroscopy show that the S-C bond acts as a bridge to quickly transfer photogenerated carriers in the composite material, and achieves the effect of high-efficiency hydrogen evolution. The hydrogen production of SgZ-45 reaches 9545 μmol·g^-1 in 5 h, which is 53 and 12 times that of g-C₃N₄ and ZIF-9, respectively. The intrinsic mechanism of photoelectron transfer through S-C bonds can be further confirmed by density functional theory (DFT) calculations. This work provides new insights for building a chemical bond electron transfer bridge between MOF derivatives and nonmetallic photocatalytic materials.

In situ composite of Co-MOF on a Ti-based material for visible light multiphase catalysis: synthesis and the photocatalytic degradation mechanism

A Co-MOF/Ti-based Z-type heterojunction prepared by an in situ growth method exhibits good photocatalytic activity for tetracycline.

Improved H-adsorption ability of Cu of CuNi alloy nanodots toward efficient photocatalytic as H2-evolution activity of TiO2

Compared with noble metal Pt, non-noble metal Cu as a cocatalyst exhibits a low hydrogen-evolution activity owing to its weak Cu-H bond (11 kcal mol-1), which inhibits the hydrogen adsorption...

Novel, Simple and Low-Cost Preparation of Ba-Modified TiO2 Nanotubes for Diclofenac Degradation under UV/Vis Radiation

A novel low-cost synthesis of barium-modified TiO2 nanotube (TNT) arrays was used to obtain an immobilized photocatalyst for degradation of diclofenac. TNT arrays were prepared by electrochemical anodization of titanium thin films deposited on fluorine-doped tin oxide (FTO) coated glass by magnetron sputtering, ensuring transparency and immobilization of the nanotubes. The Ba-modifications were obtained by annealing solutions of Ba(OH)2 spin coated on top of TNT. Three different concentrations of Ba(OH)2 were used (12.5 mM, 25 mM and 50 mM). The crystalline structure, morphology and presence of Ba were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. Ba-modified TiO2 nanotubes (BTNT) were tested for photocatalytic degradation of diclofenac under UV/Vis radiation and it was proven that all of the Ba-modified samples showed an increase in photocatalytic activity with respect to the unmodified TNTs. The most efficient photocatalyst was the sample prepared with 25 mM Ba(OH)2 which showed 90% diclofenac degradation after 60 min. This result was in agreement with cyclic voltammetry measurements that showed the largest increase in photo-oxidation current densities for the same sample due to the increased generation of •OH radicals obtained by a more efficient photogenerated charge separation.

Photodegradation of organic water pollutants under visible light using anatase F, N co-doped TiO2/SiO2 nanocomposite: Semi-pilot plant experiment and density functional theory calculations

Visible-light driven photocatalysts are of great importance in wastewater treatment. In this work, fluorine and nitrogen co-doped titanium dioxide/silica nanocomposite (F-N-TiO₂/SiO₂) was synthetized using a sol-gel approach. The as-developed nanocomposite was well characterized using different techniques. In particular, an anatase structure with high surface area (345.69 m²/g) and a band gap of 2.97 eV were observed for the as-synthesized nanocomposite, which makes it a potential candidate for photocatalytic applications under visible light. A systematic density functional theory calculation was performed to get more insight into the effect of dopant atoms on the band gap of TiO₂ nanoparticles. To enhance the reusability of the photocatalyst in semi-pilot scale, the as-developed nanocomposite was immobilized onto the glass beads by coupling dip-coating and heat attachment methods. A semi-pilot scale custom-designed fixed-bed photoreactor was used to evaluate the photocatalytic performance of the as-developed nanocomposite under both visible and solar irradiations. A mixture of three azo dyes (i.e., basic red 29, basic blue 41 and basic yellow 51) was used as the model industrial wastewater. The analysis of the wastewater showed that the complete removal of the pollutants under visible light and sunlight can occurred at pH of 3 and flow rate of 280 mL/min. The durability results demonstrated the successful degradation of the pollutants for five cycles. The results of this study show how careful controlling the operational parameters as well as using a highly photocatalytic nanomaterial can lead to successful decontamination of organic water pollutants. This approach might open up new windows to the future applications of photocatalytic nanomaterials for wastewater treatment.

Facile fabrication of AgI/Sb2O3 heterojunction photocatalyst with enhanced visible-light driven photocatalytic performance for efficient degradation of organic pollutants in water

The construction of heterojunction is considered as a promising approach to designing highly effective visible-light driven photocatalysts. In this research, the AgI/Sb₂O₃ heterojunction photocatalyst was synthesized by a simple in situ deposition-precipitation procedure, which was supported by XPS results. Among the prepared samples, the 60% AgI/Sb₂O₃ samples exhibited the best ARG degradation ratio (98.3%) in 1 h under visible light irradiation, while the pure Sb₂O₃ and AgI exhibited almost none photocatalytic performance. The trapping experiments and EPR proved that the photo-generated ·O₂^- and ·OH made major contributions to the photocatalytic degradation of ARG by the 60% AgI/Sb₂O₃ samples. The enhanced photocatalytic performance of AgI/Sb₂O₃ heterojunction photocatalysts was ascribed to that the e^- produced in the CB of AgI would be transferred to the empty CB of Sb₂O₃, which could effectively promote separation of photo-induced carries. More importantly, the transfer of electrons from AgI to Sb₂O₃ would be in favor of restraining the reduction of Ag⁺ to Ag⁰ resulting in the good stability of heterojunction photocatalysts. The heterojunction photocatalyst provided in this work might be a prospective candidate for decontamination of water.

Engineered Nanoparticles with Decoupled Photocatalysis and Wettability for Membrane-Based Desalination and Separation of Oil-Saline Water Mixtures

Membrane-based separation technologies are the cornerstone of remediating unconventional water sources, including brackish and industrial or municipal wastewater, as they are relatively energy-efficient and versatile. However, membrane fouling by dissolved and suspended substances in the feed stream remains a primary challenge that currently prevents these membranes from being used in real practices. Thus, we directly address this challenge by applying a superhydrophilic and oleophobic coating to a commercial membrane surface which can be utilized to separate and desalinate an oil and saline water mixture, in addition to photocatalytically degrading the organic substances. We fabricated the photocatalytic membrane by coating a commercial membrane with an ultraviolet (UV) light-curable adhesive. Then, we sprayed it with a mixture of photocatalytic nitrogen-doped titania (N-TiO₂) and perfluoro silane-grafted silica (F-SiO₂) nanoparticles. The membrane was placed under a UV light, which resulted in a chemically heterogeneous surface with intercalating high and low surface energy regions (i.e., N-TiO₂ and F-SiO₂, respectively) that were securely bound to the commercial membrane surface. We demonstrated that the coated membrane could be utilized for continuous separation and desalination of an oil–saline water mixture and for simultaneous photocatalytic degradation of the organic substances adsorbed on the membrane surface upon visible light irradiation.

Anti-algal activity of a fluorine-doped titanium oxide photocatalyst against Microcystis aeruginosa and its photocatalytic degradation

Fluorine-doped TiO2 was successfully synthesised and applied as algaecide. Studies on algae removal efficiencies and mechanisms illustrated that F-TiO2 was suitable for algae elimination in natural water bodies.