Conduction Band Of TiO2 Research Articles

Photocatalysis of Adsorbed Catechol on Degussa P25 TiO2 at the Air-Solid Interface.

Semiconductor photocatalysis with commercial TiO2 (Degussa P25) has shown significant potential in water treatment of organic pollutants. However, the photoinduced reactions of adsorbed catechol, a phenolic air pollutant from biomass burning and combustion emissions, at the air-solid interface of TiO2 remain unexplored. Herein we examine the photocatalytic decay of catechol in the presence of water vapor, which acts as an electron acceptor. Experiments under variable cut-off wavelengths of irradiation (λcut-off ≥ 320, 400, and 515 nm) distinguish the mechanistic contribution of a ligand-to-metal charge-transfer (LMCT) complex of surface chemisorbed catechol on TiO2. The LMCT complex injects electrons into the conduction band of TiO2 from the highest occupied molecular orbital of catechol by visible light (≥2.11 eV) excitation. The deconvolution of diffuse reflectance UV-visible spectral bands from LMCT complexes of TiO2 with catechol, o-semiquinone radical, and quinone and the quantification of the evolving gaseous products follow a consecutive kinetic model. CO2(g) and CO(g) final oxidation products are monitored by gas chromatography and Fourier-transform infrared spectroscopy. The apparent quantum efficiency at variable λcut-off are determined for reactant loss (Φ- TiO2/catechol = 0.79 ± 0.19) and product growth ΦCO2 = 0.76 ± 0.08). Spectroscopic and electrochemical measurements reveal the energy band diagram for the LMCT of TiO2/catechol. Two photocatalytic mechanisms are analyzed based on chemical transformations and environmental relevance.

Ultrafast Electron Dynamics at the P‐rich Indium Phosphide/TiO2 Interface

AbstractThe current efficiency records for generating green hydrogen via solar water splitting are held by indium phosphide (InP)‐based photo‐absorbers, protected by TiO2 layers grown through atomic layer deposition (ALD). InP is also a leading material for photonic integrated circuits and computing, where ultrafast near‐surface behavior is key. A previous study described electronic pathways at the phosphorus‐rich (P‐rich) surface of p‐doped InP(100) using time‐resolved two‐photon photoemission (tr‐2PPE) spectroscopy. Here, the intricate electron pathways of the P‐rich InP surface modified with ALD‐deposited TiO2 are explored. Photoexcited bulk InP electrons migrate through a bulk‐to‐surface transition cluster of states and surface states and inject into the TiO2 conduction band (CB). Energy levels and occupation dynamics of CB states in P‐rich InP and TiO2 adlayers are observed, with discrete states preserved up to 10 nm TiO2 deposition. Thermalization lifetimes of excited electrons > 0.8 eV above the InP conduction band minimum (CBM) are preserved for layer thicknesses up to 2.5 nm. Annealing at 300 °C to achieve crystalline TiO2 reconstructions destroys interfacial states, affecting charge transfer. These observations enable innovative engineering of the P‐rich InP/TiO2 heterointerface, opening new possibilities for studying hot‐carrier extraction, adsorbate effects, surface plasmons, and improving photovoltaic and PEC water‐splitting devices.

Novel unsymmetrical squaraine dyes for dye-sensitized solar cells: Synthesis, characterization, and comparative photovoltaic performance of USQI-NPh2Me2 and USQI-OMe

This study presents the synthesis, characterization, and photovoltaic performance of two novel unsymmetrical squaraine dyes, USQI-NPh2Me2 and USQI-OMe, engineered for application in dye-sensitized solar cells (DSSCs). These chromophores were functionalized with distinct electron-donating groups, di-p-tolylamine for USQI-NPh2Me2 and methoxy for USQI-OMe. Their molecular structures were confirmed through FT-IR, 1HNMR, 13C NMR, and mass spectrometry. Comprehensive photophysical and electrochemical studies were conducted to fine-tune the HOMO and LUMO energy levels of both dyes, optimizing charge injection into the TiO2 conduction band and facilitating dye regeneration with the iodolyte (I₃⁻/I⁻) redox mediator. USQI-NPh2Me2 exhibited a strong absorption maximum at 661 nm, achieving a high short-circuit current density (JSC) of 13.17 mA/cm2, an open-circuit voltage (VOC) of 0.71V, and an overall efficiency of 7.01 %. USQI-OMe, with its absorption peak at 651 nm, reached a JSC of 11.88 mA/cm2, a higher VOC of 0.72 V, but a slightly lower overall efficiency of 6.41 %. Both dyes demonstrated reduced aggregation on the TiO2 surface, contributing to enhanced DSSCs performance. A Comparative analysis revealed that USQI-NPh2Me2 exhibits higher efficiency, while USQI-OMe provided a greater voltage output, highlighting the influence of electron-donating groups on photovoltaic properties. These findings provide valuable insights into structure-property relationships in unsymmetrical squaraine dyes, paving the way for future DSSCs chromophore design and optimization.

Design and characterization of novel A2B2 porphyrins: Solar cell applications, antimicrobial properties, and molecular docking insights

We synthesized novel A2B2 porphyrin derivatives (5a-e, 7a,b) with yields of 60–73 %. Porphyrin 2 was prepared by reacting dipyrromethane 1 with p-bromobenzaldehyde. Porphyrin 2 was then treated with n-BuLi in DMF at -15 °C to produce porphyrin 3. The final compounds, 5a-e and 7a,b, were synthesized by reacting porphyrin 3 with activated nitriles (4a-e) and thiazolone derivatives (6a,b). The structures of the novel compounds were confirmed using infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), mass spectrometry (MS), and elemental analysis. DFT calculations were used to explore the electronic structures and energy levels of the synthesized compounds. Compounds 7a and 7b showed improved electron transfer efficiency compared to 5a-e, with HOMO and LUMO levels aligned for optimal DSSC performance. The HOMO levels are below the electrolyte's redox potential (-5.2 eV), and the LUMO levels are above TiO2's conduction band (-4.2 eV), facilitating efficient electron injection and dye regeneration. Key parameters such as open-circuit voltage (VOC), free energy of injection (ΔGinj), and regeneration (ΔGreg) were calculated, highlighting these compounds' potential for DSSC applications. The newly synthesized compounds were tested for antibacterial activity against C. albicans, B. subtilis, and E. coli. Compounds 5e (MIC50 3.125 µg/mL, with inhibition zone 45 mm against B. subtilis) and (MIC50 12.5 µg/mL, with inhibition zone 31 mm against E. coli) and 7a (MIC50 3.125 µg/mL, with inhibition zone 44 mm against B. subtilis) and (MIC50 12.5 µg/mL, with inhibition zone 30 mm against E. coli) showed the highest antimicrobial activity. Compound 5e's carboxylic acid group likely enhances activity through strong hydrogen bonding and improved solubility, aiding interaction with microbial enzymes or cell walls. Compound 7a's dimalononitrile groups, being highly electron-withdrawing, increase reactivity, while phenylthiazolidine rings offer additional binding sites through hydrogen bonding and pi-stacking interactions. Docking studies of the most potent antibacterial porphyrin analogues, 5e and 7a, against the target protein PDB: 1ECl showed promising results. Compound 5e achieved a docking score of ‐7.9559 kcal/mol with an RMSD of 1.9743 Å, while compound 7a had an even better score of ‐8.9174 kcal/mol. Compound 7a formed interactions with two H-acceptors from its cyano groups, binding to Arg136 and Lys488, and a Pi-H interaction between the thiazolone ring and Asn158, with distances of 3.19, 3.63, and 3.71 Å, respectively.

How to choose proper electron acceptor groups for highly efficient copper electrolyte-based dye-sensitized solar cells?

A better understanding of electron-accepting groups (EAGs) is important for the development of potentially efficient dyes. Density functional theory (DFT) and time-dependent DFT were employed in this study to investigate a variety of dyes derived from XY1b (11.8 %) in conjunction with prominent EAGs including 2-cyano-3-phenylacrylic acid (CPA), 2-cyano-acrylic acid (CA), and benzoic acid (BA). Various critical parameters pertaining to short-circuit current density (Jsc) and open-circuit photovoltage (Voc) were calculated, including light-harvesting ability, conduction band energy shift, dye-[Cu(tmby)2]2+ interaction, dye aggregation, and charge recombination, in order to illustrate the advantages and limitations of these EAGs. The findings indicate that dyes based on CA demonstrate a redshifted absorption spectrum, stronger electronic coupling with TiO2 conduction band, extended excited state lifetime, and enhanced dye regeneration driving force, resulting in higher Jsc compared to CPA and BA-based dyes. Regarding Voc, CA-based dyes show an increased conduction band energy shift due to their larger vertical dipole moment and reduced charge recombination with [Cu(tmby)2]2+. Additionally, it is suggested that future studies on structure–property relationships should prioritize identifying the optimal dye conformation, as it significantly influences adsorption configuration and vertical dipole moment. Overall, among the commonly utilized EAGs, CA stands out for its ability to enhance Jsc, Voc, and adsorption stability over CPA and BA-based dyes.

Light harvesting S-scheme g-C3N4/TiO2/M photocatalysts for efficient removal of hazardous moxifloxacin

The development of advanced photocatalysts with enhanced efficiency for environmental remediation is critical for addressing persistent organic pollutants like Moxifloxacin. In this study, we present a novel S-scheme heterojunction g-C3N4/TiO2/M photocatalyst designed to optimize light harvesting and charge separation for the effective degradation of Moxifloxacin. The innovative S-scheme configuration enables superior charge transfer dynamics by retaining potent photogenerated electrons in the conduction band of TiO2 and holes in the valence band of g-C3N4, significantly improving photocatalytic performance compared to conventional Type-II systems. Heterogeneous photocatalysis, particularly using TiO2-based materials, offers a promising approach. Here, we synthesized TiO2 hybridized with metal-doped g-C3N4 (GCNTM) via a simple hydrothermal method. The fabricated nanocomposites were characterized using SEM, XRD, FTIR, and UV–Vis (DRS). These GCNTM nanocomposites were employed for the degradation of hazardous Moxifloxacin (MXF) under visible light. Detailed analysis of the photocatalytic mechanism reveals that the synergistic interaction between g-C3N4, TiO2, and the co-catalyst M not only broadens the light absorption spectrum but also enhances the separation and lifespan of charge carriers. Among the synthesized materials, GCNTLa demonstrated the highest degradation efficiency, achieving 96 % removal of MXF. This enhanced activity is attributed to the effective suppression of charge recombination, leading to the generation of reactive species responsible for MXF degradation. Additionally, GCNTM showed remarkable stability and reusability, with only a 6 % reduction in efficiency after five cycles, confirming its high reusability and mechanical stability. Our S-scheme photocatalyst demonstrates a marked increase in the degradation rate of Moxifloxacin under visible light irradiation, highlighting its potential for practical environmental applications.

Simultaneous photocatalytic degradation of remdesivir, favipiravir, and diclofenac from aqueous solutions using a quaternary plasmonic Ag/Ag-SG-TiO2-rGO photocatalyst: Synthesis, characterization, optimization, and toxicity assessment

This study presents a novel quaternary plasmonic photocatalyst, Ag/Ag-Sol-Gel(SG)-TiO2-rGO, designed for efficient removal of remdesivir (RDV), favipiravir (FAV), and diclofenac (DCF) as COVID-19 antiviral drugs from water samples. Various characterization techniques were employed to analyze the Ag/Ag-SG-TiO2-rGO nanocomposites, which were synthesized with different Ag to SG-TiO2-molar ratios. The photocatalyst, containing 30 % Ag plasmonic within its framework, exhibited the highest pollutant removal under visible light. This efficiency is attributed to the surface plasmon resonance (SPR) generated by metallic Ag nanoparticles and the optimal energy alignment between the TiO2 conduction band and the rGO work function. Trapping experiments were used to identify the most active species. It was confirmed that O2− and OH were the main active species in the photocatalytic process. The degradation kinetics, following a pseudo-first-order model, was assessed using an optimized LC-MS/MS. An optimization of the photodegradation process was done using a central composite design, as well as a study of the effects of prolonged irradiation. This resulted in the total elimination of the target compounds at a dosage of 0.087 g, irradiation time of 80 min, and pH value of 8. The photodegradation efficiency of sewage treatment plant effluent and tap water was reduced by matrix components, particularly in highly contaminated samples. An additional confirmatory MTT assay revealed a very low viability difference for mouse fibroblast cells, L929, in untreated, treated (97 %) and control samples. This study sheds light on the photodegradation of anti-COVID-19 drugs and offers insights into their remediation in aquatic environments.

Far-red active squaraine dye-sensitized photoanode for dye-sensitized solar cells with a copper (II/I) electrolyte

In dye-sensitized solar cells (DSSC), controlling the dye-aggregation on TiO2 and charge recombination between electrons present in TiO2 and electrolyte can be achieved by wrapping the long alkyl groups around the dye structure and further introducing bulky donor on the dye is a potential approach to enhance both the open-circuit potential and short-circuit current parameters. Additionally, bulky donor containing dye structures modulates the photophysical and electrochemical properties of the sensitizer which helps reducing the over potentials required for the dye regeneration process by utilizing a multidentate ligand containing [Cu(tme)]2+/+ and I−/I3− redox electrolytes. Hagfeldt donor appended far-red NIR active unsymmetrical squaraine dye (SQ-HF) has been designed, synthesized, and characterized. SQ-HF dye showed an intense absorption at 676 nm (ε 1.7 × 105 M−1cm−1). Photophysical and electrochemical studies indicated that the LUMO and HOMO energy levels of the SQ-HF dye were suited for charge injection (from the LUMO of the dye to the conduction band of TiO2) and dye-regeneration processes, respectively. The DSSC device efficiency of 5.15 % (JSC of 10.83 mA/cm2 and VOC of 0.690 V) has been achieved for SQ-HF dye by utilizing a literature reported [Cu(tme)]2+/+ and 4.11 % (JSC of 8.74 mA/cm2 and VOC of 0.702 V) in I−/I3− redox shuttles, respectively.

Pyrazine-Based Aromatic Dyes as Novel Photosensitizers with Improved Conduction Band and Photovoltaic Features: DFT Insights for Efficient Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have garnered significant attention due to their exceptional ability to convert solar energy into electricity at a relatively low cost. Novel organic photosensitizers (FZB1-FZB9) from the pyrazine-based aromatic dye (E)-3-(5-(2,3-bis(40-(diphenylamino)-[1,10-biphenyl]-4-yl)-7 (trifluoromethyl)quinoxalin-5-yl)thiophen-2-yl)-2-cyanoacrylic acid (TPPF) have been quantum chemically modeled for their application in dye-sensitized nanocrystalline TiO2 solar cells (DSSCs). The electrochemical and photovoltaic features of modeled dyes are investigated by performing DFT insights, i.e. FMOs, absorption maxima, DOS, TDM, NBO, exciton and binding energy, radiative lifetime analysis (ꚍ), electron-injection (Δ G inject ) and regeneration analysis ( Δ G dye regen )@TiO2. FMO analysis confirmed the better electron injection as HOMO of designed dyes was found to be more positive than redox potential I/I3 (-4.8 eV), and the LUMO appeared more negative than the conduction band of TiO2 (-4.0 eV). The modeled photosensitizers exhibited red shift λmax from 338-494 nm with a lower energy gap from 5.62 eV in FZB (R) to 5.17 eV in FZB9. Bridging modification reduces the exciton and binding energy for designed dye FZB9 and FZB7 compared to reference FZB. The designed dyes appeared with a lower radiative lifetime of up to 1.32 than the reference dye of 1.63, better light harvesting efficiency (LHE), and the highest NBO charge on bridges of designed photosensitizers for enhanced light emitting efficiency. The investigated dyes exhibited more negative values for electron injection, i.e. −0.003 and the highest values of dye regeneration ( Δ G regedye regen ) up to 11.717, which unveils innovative and effective injection of electrons toward semiconductor TiO2. Among all dyes, FZB8 proved best with the novel bridging modification that enables quick charge transfer as exhibited the lowest gap (5.17 eV), lowest excitation energy, better LHE, highest charge on LUMO and more negative electron injection (Δ G inject ) . The outcomes of this computational study confirmed that this research established a new benchmark for achieving novel and efficient photosensitizers, thus recommending them for future DSSC applications.

Synergistic charge-transfer dynamics of novel D-D-A-π-A framework containing indoline-benzo[d][1,2,3]thiadiazole based push-pull sensitizers: from structural engineering to performance metrics in photovoltaic solar cells.

Dye-sensitized solar cells (DSSCs) present a convincing substitute for conventional silicon-based solar cells because of their possible lower manufacturing costs and versatile uses. Electron injection and dye regeneration processes are important in meeting the need for photosensitizers with improved efficiency and stability. Aimed at enhancing the performance and efficiency of DSSCs, this study focuses on the structural engineering to performance metrics of novel indoline-benzo[d][1,2,3]thiadiazole based push-pull sensitizers (LHZ1 to LHZ9) with D-D-A-π-A framework. The current study provides insights into the photovoltaic and optoelectronic properties of the investigated dyes, which are significantly influenced by the modification of auxiliary donors (D), internal acceptors with thiophene as a spacer, and cyanoacrylic acid (A) as the terminal acceptor. These modifications enhance rapid charge transfer among the dyes, highlighting the critical role of dye-semiconductor interactions. The suitability of developed sensitizers for DSSCs applications is confirmed by executing quantum methods like NBO, TDM, FMO, DOS, Eb, ΔGreg, ΔGinject, VRP, and ICT parameters qCT (e-), DCT ( ), H index ( ), ∆( ), t index ( ), and μCT (D). All of the investigated dyes have HOMO levels lower than the electrode I-/I3-'s redox potential (-4.8 eV) and LUMO values that are appropriately higher than the conduction band of TiO2 (-4.0 eV). The novel dyes showed a closing of the energy gap (2.38-1.84 eV). The LHZ7 and LHZ8 molecules with the lowest Eg (1.97 eV and 1.84 eV) demonstrated the highest absorption (up to 746 nm > 402 nm for LHZ), which was caused by the insertion effect of varied donors and internal acceptors. Almost all photosensitizers appeared with remarkable properties, i.e., red-shifted absorption maxima (746 nm), lowest Ex (1.66 eV), Eb (0.02 eV), and highest values of LHE (0.958). The TDM analysis revealed high charge density on HOMO of donor and LUMO of acceptors in designed dyes. DOS analysis revealed that the donor parts of the molecules delocalized the highest occupied molecular orbitals of dye particles. The electronic properties predicted by the NBO analysis showed that donor groups donate high and faster transfer of charge, and internal acceptor groups rapidly accept them. The electron injection (ΔGinject) and dye regeneration (ΔGreg) analysis of photosensitizers attached with TiO2 proved efficient charge transfer properties from the donor of newly designed dyes onto the conduction band of TiO2. This study, also supported by the thermodynamic stability of dyes with negative values of Gibbs free energy, revealed that the performance of the designed dyes is augmented by modifying the donor and internal acceptors of the reference photosensitizer for effective application in the experimental community. All of the dyes are suitable for DSSCs based on the calculated parameters. Still, the LHZ9 dye proved proficient in applying dye-sensitized solar cells due to its remarkable properties, i.e., lowest gap and red-shifted absorption maxima.

Molecular Design and DFT Analysis of High-performance Dyes Based on Pyrene with Different Donor Parts and Their Optoelectronic Applications.

The performance and efficacy of dyes, which are crucial photon-harvesting components in dye-sensitized solar cells (DSSCs), must be meticulously analysed at the molecular level. This research focuses on a theoretical investigation of dye characteristics rather than the synthesis of novel compounds. Using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT), we have analysed six D-π-A structure dyes designed with pyrene as the π-bridge and various functional groups as donors. Our study examines their geometrical, electronic, optical, electronic localization, and electrochemical properties. The findings reveal that these theoretically designed D-π-A dyes show significant improvements in light-harvesting efficiency, open-circuit photovoltage, electron injection efficiency, and overall photovoltaic performance. The analysis indicates effective electron injection from each dye into the conduction band of TiO2, followed by efficient regeneration and enhanced intra- and intermolecular charge transfer properties. The incorporation of pyrene as a π-bridge and the use of different functional groups as donors are crucial for facilitating electron transfer from the donor to the acceptor region. Among the dyes studied, the D-π-D modified dye demonstrates superior theoretical performance, attributed to its higher energy levels of the lowest unoccupied molecular orbital and greater oscillator strengths for excited states. This results in improved intramolecular electron transfer and electron injection into the conduction band of TiO2, followed by effective regeneration. Overall, our study highlights the potential of these theoretically modeled dyes as highly promising sensitizers for DSSCs, due to their exceptional optical and electronic properties and impressive photovoltaic parameters. These findings position these molecular structures as strong candidates for future applications in organic DSSCs.

Theoretical Investigation of the Effects of Aldehyde Substitution with Pyran Groups in D-π-A Dye on Performance of DSSCs.

This work investigated the substitution of the aldehyde with a pyran functional group in D-π-aldehyde dye to improve cell performance. This strategy was suggested by recent work that synthesized D-π-aldehyde dye, which achieved a maximum absorption wavelength that was only slightly off the threshold for an ideal sensitizer. Therefore, DFT and TD-DFT were used to investigate the effect of different pyran substituents to replace the aldehyde group. The pyran groups reduced the dye energy gap better than other known anchoring groups. The proposed dyes showed facile intermolecular charge transfer through the localization of HOMO and LUMO orbitals on the donor and acceptor parts, which promoted orbital overlap with the TiO2 surface. The studied dyes have HOMO and LOMO energy levels that could regenerate electrons from redox potential electrodes and inject electrons into the TiO2 conduction band. The lone pairs of oxygen atoms in pyran components act as nucleophile centers, facilitating adsorption on the TiO2 surface through their electrophile atoms. Pyrans increased the efficacy of dye sensitizers by extending their absorbance range and causing the maximum peak to redshift deeper into the visible region. The effects of the pyran groups on photovoltaic properties such as light harvesting efficiency (LHE), free energy change of electron injection, and dye regeneration were investigated and discussed. The adsorption behaviors of the proposed dyes on the TiO2 (1 1 0) surface were investigated by means of Monte Carlo simulations. The calculated adsorption energies indicates that pyran fragments, compared to the aldehyde in the main dye, had a greater ability to induce the adsorption onto the TiO2 substrate.

Low‐cost 0D and 2D carbon material co‐decorated titanium dioxide ternary heterojunction for rapid and efficient bacteria killing under visible light

AbstractRecently, the issue of bacterial resistance has gotten worse because of the overuse of antibiotics. The newborn superbacteria, such as vancomycin‐resistant bacteria, were hard to kill, inspiring researchers to find new ways to kill the bacteria efficiently. TiO2 was used as an efficient photocatalyst for water splitting and pollutant degradation. However, the weak efficiency limited the application to solve the drug‐resistance problem. Consequently, the incorporation of low‐cost 0D carbon quantum dots (CQDs) and 2D graphene oxide (GO) was pursued to amplify the visible light absorption capabilities of TiO2 and thereby elevate its photocatalytic activity. After forming the heterogeneous interface of CQDs and TiO2, CQDs converted part of visible light into wavelength less than 400 nm using the up‐conversion property. The modification of CQDs enabled electrons to be easily transferred from the conduction band of CQDs to the conduction band of TiO2. Meanwhile, GO can act as an electron acceptor, reduce the recombination efficiency of holes and electrons, and transfer the photogenerated electrons in the redox reaction in the heterogeneous interface. Because of the excellent absorption of GO, TiO2/CQDs/GO reached 57.8°C after 20 min irradiation under 1.5 times sunlight, which provided a prerequisite for photodynamic antibacterial therapy/photothermal antibacterial therapy synergistic antibacterial potential. TiO2/CQDs/GO possessed an antibacterial efficiency as high as 99.3% toward Staphylococcus aureus which has a bright future in disinfection in vivo and medical devices as well as water sterilization.

Oxidation cocatalyst/S-scheme junction cooperatively assists photocatalytic H2 production in ternary hybrid: The case of PdO@TiO2-Cu2O

Solar-driven photocatalytic hydrogen production from water splitting holds significant potential in addressing the energy crisis and environmental pollution. However, rapid recombination of photogenerated carriers and insufficient surface catalytic reaction kinetics hinder the photocatalytic process. Constructing the catalytic systems with multi-channel charge-separation can effectively alleviate those issues. In this work, ternary PdO@TiO2-Cu2O composites have been synthesized through precursor calcination and low-temperature reduction, where PdO and Cu2O nanoparticles couple with the TiO2 nanorods. Comparing to single TiO2, binary PdO@TiO2 and TiO2-Cu2O, the PdO@TiO2-Cu2O hybrid exhibits enhanced photocatalytic hydrogen production performance (5831μmol g-1h−1), with a hydrogen production rate more than three times that of single TiO2. Based on the band structures of TiO2 and Cu2O, along with the photochemical/electrochemical, in-situ EPR, Photoluminescence (PL) tests, and work function calculations, the formation of an S-scheme heterojunction at the TiO2-Cu2O interface under light illumination facilitates the recombination of electrons in the conduction band (CB) of TiO2 with holes in the valence band (VB) of Cu2O. In this regard, the established built-in electric field significantly accelerates the transfer of photogenerated charges while preserving their respective strong oxidation and reduction capabilities. Meanwhile, the introduction of PdO enriches the holes and further enhances the rate of charge separation. This S-scheme heterojunction with directional charge transfer and oxidation cocatalyst collectively form multi-channels of charge separation, optimizing charge migration and enabling efficient hydrogen production, thus improving the photocatalytic capability of pristine TiO2. This study provides a rational approach to construct efficient S-scheme heterojunction/oxidation cocatalyst multi-component catalytic systems for water splitting into hydrogen.

Synthesis, Crystal Structure, and Theoretical Screening of Solvatochromism and Light-Harvesting Performance of Hexamine V-Substituted Lindqvist-Based Photosensitizer for Photovoltaic Solar Cells.

In this paper, we employ density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches to predict the solvatochromism and light-harvesting properties of a newly synthesized hybrid hexamine (HMTA) vanadium-substituted Lindqvist-type (V 2 W 4 ) polyoxometalate (POM), (C7H15N4O)2(C6H13N4)2[V2W4O19]·6H2O, (HMTA-V 2 W 4 ) for application in dye-sensitized solar cells (DSSCs). Single crystal X-ray diffraction (XRD) and noncovalent interaction (NCI) analyses show a 3D-supramolecular packing stabilized by means of hydrogen bonds and van der Waals (vdW) and ionic interactions between highly nucleophilic cage-like HMTA surfactant, lattice water, and electrophilic V 2 W 4 polyanions. Experimental and theoretical UV/vis absorption spectra show large absorption in the visible region, which is strongly solvent polarity dependent. This solvatochromic behavior can be attributed to hydrogen bonding interactions between the V 2 W 4 polyanion and protic solvents. Furthermore, the energy level of semiconductor-like nature of HMTA-V 2 W 4 with high LUMO level matches well with the conduction band (CB) of TiO2, which is beneficial for the photovoltaic device performance. The photovoltaic empirical parameters are theoretically predicted to demonstrate a remarkably high open-circuit voltage (Voc) value (1.805 eV) and a photoelectric conversion efficiency (PCE) value up to 8.7% (FF = 0.88) along with superior light-harvesting efficiency (LHE) (0.7921), and therefore, the studied compound is expected to be a potential candidate as a photosensitizer dye for applications in DSSCs. The aim of this work was to broaden the range of applications of POMs, owing to their low-cost fabrication, leveraging and flourishing optoelectronic properties, and ever-improving efficiency and stability for use in future technology pointed to the development of clean and green renewable energy sources to solve the current energy crisis.

A polysaccharide extracted from guar beans-based gel polymer electrolytes for efficient dye-sensitized solar cells

Liquid electrolytes in dye-sensitized solar cells (DSSCs), while effective in minimizing recombination of TiO2 conduction band with redox couple (I−/I3−), suffer from leakage and evaporation issues, hindering commercialization. Although solid-state electrolytes were introduced as an alternative, their performance is constrained by poor electrode contact. To solve these issues, gel polymer electrolytes (GPE) have been formulated based on guar gum (GG) crosslinked with poly (ethylene glycol) (PEG 200) incorporating potassium iodide (KI) as the doping salt. The incorporation of PEG 200 into the GPE allows a stable gel polymer electrolyte to form by using dimethyl sulfoxide (DMSO) as the organic solvent. The GPE boasts a structure free from leakage, showcases captivating ionic conductivity and thermal stability. Comprehensive structural and thermal analyses, including Fourier Transform Infrared spectroscopy (FTIR), Differential Scanning Calorimeter (DSC), and Thermogravimetric Analysis (TGA) have been carried out. The electrochemical properties of the GPE were also studied via Electrical Impedance Spectroscopy (EIS) and are significantly enhanced with higher concentration of KI introduced into the GPE. The highest ionic conductivity (σ) value of 9.76 × 10−3 S cm−1 is obtained in the GPE contained 40 wt% KI, with an efficiency of 5.65 %. Importantly, this study introduces a better and effective approach for designing electrolyte materials with high ionic conductivity, efficiency, and stability in DSSC.

The Influence of Au Loading and TiO2 Support on the Catalytic Wet Air Oxidation of Glyphosate over TiO2+Au Catalysts

This study aimed to explore the impact of varying amounts of added Au (0.5 to 2 wt.%) and the structural characteristics of anatase TiO2 supports (nanoparticles (TP, SBET = 88 m2/g) and nanorods (TR, SBET = 105 m2/g)) on the catalytic efficiency of TiO2+Au catalysts in eliminating the herbicide glyphosate from aqueous solutions via the catalytic wet air oxidation (CWAO) process. The investigation was conducted using a continuous-flow trickle-bed reactor. Regardless of the TiO2 support and the amount of Au added, the addition of Au has a positive effect on the glyphosate degradation rate. Regarding the amount of Au added, the highest catalytic activity was observed with the TP + 1% Au catalyst, which had a higher Schottky barrier (SB) than the TP + 2% Au catalyst, which helped the charge carriers in the TiO2 conduction band to increase their reduction potential by preventing them from returning to the Au. The role of glyphosate degradation product adsorption on the catalyst surface is crucial for sustaining the long-term catalytic activity of the investigated TiO2+Au materials. This was particularly evident in the case of the TR + 1% Au catalyst, which had the highest glyphosate degradation rate at the beginning of the CWAO experiment, but its catalytic activity then decreased over time due to the adsorption of glyphosate degradation products, which was favoured by the presence of strong acidic sites. In addition, the TR + 1% Au solid had the smallest average Au particle size of all analyzed materials, which were more easily deactivated by the adsorption of glyphosate degradation products. The analysis of the degradation products of glyphosate shows that the oxidation of glyphosate in the liquid phase involves the rupture of C–P and C–N bonds, as amino-methyl-phosphonic acid (AMPA), glyoxylic acid and sarcosine were detected.

Enhancing the performance of pyridyl carboxamide-N,N-dimethyl amino chalcone (PCC) as a dye sensitizer for dye-sensitized solar cells (DSSCs) through the incorporation of electron donor moieties

This study has focused on enhancing the performance of pyridyl carboxamide-N,N-dimethyl amino chalcone (PCC) as a sensitizer for dye-sensitized solar cells (DSSCs) by strategically incorporating electron donor moieties identified in a literature review. Our reviewing the previous reports highlights the pivotal role of electron donors in optimizing light harvesting, electron injection, and overall power conversion efficiency in organic dye sensitizers, particularly those following a donor-bridge-acceptor (D-π-A) architecture. The selected donor moieties, including dithieno[3,2-b:2′,3′-d]thiophene (DTT), benzodithiophene (BDT), triphenylamine (TPA), carbazole (CBZ), and triazatruxene (TAZ), are systematically introduced into the molecular structure of PCC (abbreviated as PCC-DTT, PCC-BDT, PCC-TPA, PCC-CBZ, and PCC-TAZ, respectively). The performance of these modified compounds is rigorously evaluated using density functional theory (DFT) methods. Validation results revealed that the most reliable method for PCC derivative characterization involved the combination of the functional B3PW91 with a 6-31G(d) basis set. The results indicate that the incorporation of certain donor moieties, particularly BDT, significantly enhances the electronic and optical properties of PCC, including lower HOMO energy levels, a narrow energy gap (Egap), enhanced absorption intensity, and a redshift in absorption peaks. Evaluation of photovoltaic properties including electron injection (ΔGinj), and open circuit voltage (Voc), indicated facilitating spontaneous electron injection from the dyes to the TiO2 conduction band. Notably, PCC-TAZ demonstrated the lowest electron regeneration (ΔGreg), suggesting a notable potential for efficient electron regeneration.

Antibacterial Activity of Visible Light Responsive‐Silver‐Nanoparticle/Titania Composite Thin Films with Unprecedently Higher Amounts of Silver

AbstractTo study the antibacterial efficacy of metallic Ag nanoparticle/titania (Ag‐NP)/TiO2 composite thin films against Escherichia coli (ATCC 25922), COMP‐Agn with various amounts of Ag (10 mol% ≤ n ≤ 80 mol%) are fabricated on a quartz glass substrate at 600 °C using the molecular precursor method. The films are characterized by X‐ray diffraction, X‐ray photoelectron, scanning electron microscopy, transmission electron microscopy, photoluminescence, and UVvis techniques. The analysis reveals that the films are composed of metallic Ag‐NPs embedded in a mixture of anatase and rutile matrix, with a volumetric fraction of Ag ranging from 0.18 to 0.68. The antibacterial activity of the TiO2 thin film and COMP‐Agn are determined by disk diffusion and viable cell count methods. Neither pure TiO2 nor pure Ag films exhibit any discernible antibacterial under dark and visible light. The antibacterial of Ag content in composite films is observed to persist for a maximum increase of 70%. The model is proposed on the basis of photoexcited electron transfer from Ag NPs to the TiO2 conduction band of COMP‐Agn, which clarifies the main factors affecting the photoresponse and the excellent response to visible light via surface plasmon resonance.

Enhancement of visible light response of TiO2 photocatalyst by 3D-deposited Ag nanowires and its charge separation mechanism

In 3D-deposited AgNW/TiO2, which is prepared by spray-applying titanium dioxide suspension to deposited silver nanowire sheets, the synergistic effects of increased crossing points of AgNWs to enhance localized surface plasmon resonance excitation and longer-lived electrons in the conduction band of TiO2 generated by plasmon-induced charge transfer have successfully resulted in photocatalytic activity in the visible light range. We have developed photocatalytic sheets in which TiO2 particles are uniformly attached to 3D-deposited AgNWs. Regarding the prepared sheet, it was confirmed that TiO2 was indeed well adhered to the AgNWs, and electron transfer was efficient at the interface. This sheet solves the problem that the response wavelength range of the photocatalytic reaction using TiO2 is only in the ultraviolet region and exhibits sufficient photocatalytic effect in the visible light region. Transient absorption spectroscopy measurements in the diffuse reflectance configuration confirmed that the electrons of AgNWs actually move into the conduction band of TiO2 under visible light and that the interaction is independent of the excitation light intensity, thereby extending the lifetime of the electrons.