Morphology Of TiO Research Articles

Tailoring Interface via Tuning the Phase and Morphology of TiO2 for Efficient Mesoporous Perovskite Solar Cells.

The efficiency of mesoporous perovskite solar cells (mp-PSCs) is significantly influenced by favorable charge transport properties across their various interfaces. The interfaces involving compact-TiO2, mesoporous electron transport layer (ETL), and perovskite layer are particularly vital for high-performing devices. Our study presents a combined experimental and computational approach, specifically employing density functional theory, to explore the impact of mesoporous-ETL/perovskite interface properties on carrier transport. These properties are examined in relation to the phases and morphologies of the mesoporous layer. Different phases of TiO2, including anatase, rutile, and brookite, and various morphologies such as nanocubes, nanorods, and disks/clusters, were synthesized using a simple hydrothermal synthesis route. They constitute the mesoporous layer, and Cs0.05FA0.84MA0.14PbI2.55Br0.45 is used as the perovskite absorber in mp-PSCs. The performance of the resulting mesoporous-TiO2 (mp-TiO2) device was investigated in relation to the different phases and morphologies of mp-TiO2. The mp-PSCs with the anatase phase as the mesoporous ETL exhibited the highest device parameters, including power conversion efficiency of 19.15%, short-circuit current density of 22.55 mA/cm2, fill factor of 76.50%, and open-circuit voltage of 1.11 V. The superior performance of the anatase structure is attributed to its promising band edge alignment, which results from a small negative conduction band offset compared to other phases, thereby enhancing carrier transport. This study underscores the potential of interface optimization to improve device performance. By investigating the device performance across different phases and morphologies of the mp-TiO2 layer, we can pave the way for the design of next-generation energy devices.

Synthesis of Ag/Cu decorated 3D self-assembled nanowire TiO2 photocatalyst for hydrogen production: a promising pathway towards sustainable energy generation.

Here, synthesis and characterization of TiO2 with different morphologies along with the cost-effective bimetallic decoration on optimized 3D self-assembled nanowire TiO2 (NWT) photocatalyst (Ag/Cu-NWT) with overwhelming hydrogen production rate is reported. All the photocatalysts were well characterized by different characterization techniques. Initially, the effect of morphology change obtained by changing the NaOH concentration has been studied for TiO2. Morphology obtained at 10M NaOH solution, i.e., NWT (678μmol/g), showed better hydrogen production than morphology obtained at 5M (410μmol/g), 15M (210μmol/g), and 20M (160μmol/g) NaOH solutions. Further, with the aim to achieve comparable or better activity low-cost photocatalyst as compared to Pt-TiO2 system, NWT was decorated with various Cu percentages and then with a minimal percentage of Ag on an optimized Cu-NWT photocatalyst. The observed trend for photocatalytic hydrogen production has been found to be P25 TiO2 < NWT < 1.0Cu-NWT < 0.5Pt-NWT ≤ 0.1Ag/1.0Cu-NWT. The marked increase by a factor of 103 in hydrogen production for the optimized bimetallic 0.1Ag/1.0Cu-NWT (10,184μmol/g) photocatalyst compared to P25 TiO2 (99μmol/g), nearly threefold increment in hydrogen production than an optimized 1.0 Cu-NWT (3907μmol/g) photocatalyst and comparable hydrogen production as compared to 0.5Pt-NWT (10,050μmol/g) may be attributed to the successful synthesis of a highly porous NWT morphology, which offers large surface area, increased light absorption combined with the synergistic effects of surface plasmon resonance (SPR), and the Schottky barrier for H+ reduction to H2 gas. The optimization of TiO2 morphology and an inexpensive bimetallic decoration strategy opens up promising opportunities for the development of cost-effective photocatalysts in the realm of energy and environment.

Precisely regulated crystalline phase of TiO2@composite G doped with Al3+: For the preparation of highly conductive, corrosion resistant conductive coatings

The development of conductive materials is crucial to the upgrading of modern science and technology industries. In recent years, the research on conductive materials synthesized based on TiO2 has mainly focused on improving the conductivity and stability of the materials. And this study, based on the high conductivity of the material, innovatively proposes a method to precisely regulate the crystal phase and morphology of TiO2 by CH3COOH and temperature together. Meanwhile, the heterostructure was successfully built by doping Al3+ into the TiO2 lattice, and a new conductive pathway (Al-O-C) was constructed. Finally, the composite G was prepared as an Al3+-doped TiO2 composite G (Al-T/G) functional material, and it was verified by first-principles calculations (DFT). The experimental results show that the Al-T/G material not only has the low surface resistance and high whiteness of TiO2, but also is endowed with more excellent resistivity (0.203 Ω·cm) and protection efficiency (92.45 %). Meanwhile, compared with the conventional antimony-doped tin dioxide (ATO) conductive materials, the Al-T/G functional materials prepared in this paper are basically harmless to the environment in the experimental process while ensuring high conductivity. Most importantly, this paper explores the bonding mechanism of Al3+-doped TiO2 conductive materials, which provides new insights and ideas in the field of dopant-modified TiO2 conductive materials.

Mn doping and core-shell engineering of silane-modified Mn-TiO2@SiO2 nanoparticles with drastically reduced photocatalytic activity for transparent UV-shielding hybrid materials

The photocatalytic ability and incompatibility with the organic matrix of TiO2 limit its application in UV-shielding hybrid materials. Tuning the electronic structure and engineering the morphology of TiO2 are effective in reducing photocatalytic activity but remain challenging in drastic reduction. Herein, a Mn-TiO2@SiO2 structure with an average size of 24.4 nm is constructed via a combination strategy of Mn doping and core–shell engineering to accelerate the recombination of carriers and build surface barriers. Impressively, compared with pure TiO2, the 2 %Mn-TiO2@SiO2 shows 336, 447, and 237 times lower photocatalytic reaction rate constants (k) for the degradation of three dyes (reactive red 120, methyl orange, and methyl blue), respectively, demonstrating the drastically reduced photocatalytic activity of Mn-TiO2@SiO2 structure. The characterizations and density functional theory calculations reveal that Mn doping introduces an occupied deep level and an unoccupied shallow level, which facilitates the co-trapping of electrons and holes, accelerating the recombination of carriers, and the SiO2 shell serves as a barrier to mitigate the interfacial charge transfer. Additionally, surface modification using silanes enables monodisperse core–shell structure and improves its compatibility with substrates, providing the UV-shielding Mn-TiO2@SiO2-C12 silane/fluorocarbon hybrid coatings with high transparency and anti-UV aging ability.

2D TiO2 Nanosheets Decorated Via Sphere-Like BiVO4: A Promising Non-Toxic Material for Liquid Phase Photocatalysis and Bacterial Eradication.

An in-depth investigation was conducted on a promising composite material (BiVO4/TiO2), focusing on its potential toxicity, photoinduced catalytic properties, as well as its antibiofilm and antimicrobial functionalities. The preparation process involved the synthesis of 2D TiO2 using the lyophilization method, which was subsequently functionalized with sphere-like BiVO4 through wet impregnation. Finally, we developed BiVO4/TiO2 S-scheme heterojunctions which can greatly promote the separation of electron-hole pairs to achieve high photocatalytic performance. The evaluation of concentration- and time-dependent viability inhibition was performed on human lung carcinoma epithelial A549 cells. This assessment included the estimation of glutathione levels and mitochondrial dehydrogenase activity. Significantly, the BiVO4/TiO2 composite demonstrated minimal toxicity towards A549 cells. Impressively, the BiVO4/TiO2 composite exhibited notable photocatalytic performance in the degradation of rhodamine B (k=0.135 min-1) and phenol (k=0.016 min-1). In terms of photoinduced antimicrobial performance, the composite effectively inactivated both gram-negative E. coli and gram-positive E. faecalis bacteria upon 60 minutes of UV-A light exposure, resulting in a significant log 6 (log 10 CFU/mL) reduction in bacterial count. In addition, a 49 % reduction of E. faecalis biofilm was observed. These promising results can be attributed to the unique 2D morphology of TiO2 modified by sphere-like BiVO4, leading to an increased generation of (intracellular) hydroxyl radicals, which plays a crucial role in the treatments of both organic pollutants and bacteria. This research has significant potential for various applications, particularly in addressing environmental contamination and microbial infections.

Enhancing structural and optical properties of titanium dioxide nanoparticles (TiO2 NPs) incorporating with indium tin oxide nanoparticles (ITO NPs): effects of annealing temperature

TiO2 NPs and ITO NPs embedded systems are vital for surface modification in various applications. Enhancing the characterization of TiO2 NPs/ITO NPs nanoparticles to improve application efficiency is a key research direction. This study focuses on characterizing nanocomposites using TEM, SEM, XRD, UV-Vis spectroscopy, EDS, and PL spectroscopy. TiO2 NPs and ITO NPs were separately prepared using the sol-gel method, and their hybridization was achieved through an appropriate method. TEM images reveal the nano size of TiO2 NPs and TiO2 NPs/ITO NPs, with mean diameters of 12.25 ± 13 nm and 11.43 ± 11 nm, respectively. Hexagonal structures like nanoparticles are observed in the TEM analysis. SEM images demonstrate the uniform dispersion and smooth surface morphology of TiO2 NPs/ITO NPs. XRD analysis confirms the crystalline nature of TiO2 NPs, corresponding to specific crystallographic planes in the hexagonal structure. The addition of ITO NPs induces a redshift in the UV-Vis spectra, suggesting an influence on the bandgap of TiO2 NPs and potential applications in photocatalytic degradation and solar energy utilization. Photoluminescence spectroscopy reveals optical characteristics of the TiO2 NPs/ITO NPs hybrid nanostructures, with a visible emission peak redshift nm at room temperatures ranging from 400 °C to 600 °C. These findings contribute to understanding the optical behavior and interaction between ITO NPs and TiO2 NPs in the hybrid nanostructures. Overall, these characterization techniques provide valuable information on size, shape, crystallinity, optical properties, and interactions within the nanocomposites, benefiting further research and potential applications.

Synergetic regulation of interfacial electronic structure of Cu, N co-doped carbon modified TiO2 for efficient photocatalytic CO2 reduction

TiO2 was a promising candidate material for CO2 photoreduction, but its development was greatly limited due to inherent defects such as high recombination rate of photogenerated charge carriers and limited number of active sites. In this study, a method involving chelation of metal ions with amino acids followed by high-temperature pyrolysis was employed to prepare Cu, N co-doped carbon-modified TiO2 composite materials, aiming to enhance the photocatalytic CO2 reduction performance of TiO2. The introduction of Cu, N co-doped carbon effectively improved the surface morphology of TiO2, increased the specific surface area and porosity, and enhanced the adsorption capacity of CO2. Simultaneously, the modification of TiO2 by Cu, N co-doped carbon optimized the electronic structure of catalysts, facilitating the separation and transfer of photogenerated electron-hole pairs, reducing charge carrier recombination, and thereby synergistically improving the thermodynamics and kinetics of CO2 reduction. Photocatalytic performance tests revealed that 10 % Cu-TiO2 exhibited the best CO2 reduction performance at a calcination temperature of 450 °C, with a CO production rate of up to 46 μmol·g−1·h−1, approximately 18 times that of pure TiO2. Density functional theory (DFT) calculations further confirmed that the introduction of Cu, N co-doped carbon reduced the Gibbs free energy of the CO2 reduction reaction, promoting the reaction. This study provides a simple, cost-effective strategy for developing efficient photocatalytic CO2 reduction materials.

Study of Microstructure, Morphology and Functional Groups of Titanium Dioxide (Tio2) Impregnated With Copper (Cu)

This research aims to determine the differences in the microstructure, morphology, and functional groups of TiO2 (P-25) after being impregnated with Cu. Cu-impregnated TiO2 samples are synthesized using the impregnation method with TiO2 (P-25) and copper sulfate as precursors. The microstructure and functional groups of TiO2 (P-25) and Cu-TiO2 were investigated using X-ray diffraction (XRD), scanning electron microscope-energy dispersive x-ray (SEM-EDX), and Fourier transform infrared (FTIR) analysis. The lattice parameters (a, b, and c) of the TiO2 sample were found to be a = b = 0.3778 nm, c = 0.9494 nm, and these values increased to a = b = 0.3779 nm, c = 0.9496 nm after the addition of Cu. The distance between the lattices of the TiO2 sample was measured at 0.3505 nm and increased to 0.3509 nm after Cu addition. The average crystallite size of the TiO2 sample was 33 nm, which increased to 43 nm after Cu impregnation. The strain value decreased from 2.76×10^(-3) to 1.82×10^(-3) after Cu addition. SEM results revealed that the morphology of the particles from the Cu-doped synthesis showed agglomeration. The success of Cu doping was confirmed by EDX mapping, which showed the presence of Ti, O, and Cu evenly distributed on the TiO2 surface. The FTIR spectrum indicated that TiO2 (P-25) and Cu-TiO2 particles had absorption peaks at similar wave numbers. However, in the absorption area of 1000 cm^-1 to 1250 cm^-1, new absorption bands affiliated with Cu-O bonds appeared in the Cu-TiO2 sample, resulting from TiO2 vibrations after Cu addition.

Efficient synthesis and lithium storage performance of SiO2/TiO2 composite film anode by plasma electrolytic oxidation

SiO2/TiO2 composite films with different phase ratios have been successfully fabricated via the one-step plasma electrolytic oxidation (PEO) method in an alkaline electrolyte on Ti foil to obtain a binder-free anode for Li-ion batteries. The formed composite films present porous morphology of TiO2 with a uniform distribution of SiO2. The specific capacity can stabilize above 400 mAh/g at the current density of 100 μA cm−2 for 500 cycles, together with the apparent improved initial coulombic efficiency of 88.7 % and excellent rate capability, which arises from the peculiar structure and the synergic enhancement effect of SiO2 active materials and TiO2 matrix. This work provides an efficient and low-cost route for the preparation of Li-ion battery binder-free anodes and enriches the application of plasma electrolysis technology in energy field.

Design and fabrication of layered TiO2/rGO composited photoanode and its photovoltaic performance regulation for dye-sensitized solar cells

To improve the photovoltaic performance of the traditional TiO2 photoanode for dye-sensitized solar cells (DSSCs), a series of layered TiO2/rGO composited DSSCs photoanode was assembled by changing the morphologies of the TiO2 and introducing reduced graphene oxide (rGO) into different areas of the photoanode films. Firstly, TiO2 nanoflowers (TiO2-NFs), TiO2 nanorods (TiO2-NRs) were prepared employing the hydrothermal method and used as photoanode materials to explore the synergistic effect of TiO2 with different morphologies in layered photoanode. Then, TiO2-NFs/rGO composited photoanode (TNF/rGO) were fabricated to research the mechanism of rGO on improving electron transmission in the layered photoanode. The effect of adding rGO at different parts of the layered photoanode on the performance of DSSCs was also investigated. Attributing to the enhancement of light absorption and charge transfer, a champion power conversion efficiency (η) of 9.21 % (Jsc = 23.36 mA cm−2, Voc = 0.74 V, FF = 0.53) was achieved with the layered TiO2/rGO composited photoanode containing two consecutive layers of TiO2-NFs/rGO and P25/rGO, which exhibited an 82.01 % increase than traditional TiO2 (pure P25) photoanode (η = 5.06 %, Jsc = 12.09 mA cm−2, Voc = 0.73 V, FF = 0.58). It is an effective way to design and fabrication of layered TiO2/rGO composited photoanode to regulate the photovoltaic performance of traditional TiO2 photoanode for DSSCs based on the synergistic effect of its multi-layer structure, TiO2 morphologies and introduction of rGO.

Nitrogen assisted one-step hydrothermal synthesis of commercial TiO2 for methylene blue degradation under visible light irradiation

Strategies to make more efficient use of sunlight have been developed. Different synthesis parameters have been studied for the production of multiphase photocatalysts. In this work, for the first time, the performance of a one-step nitrogen-assisted hydrothermal synthesis of TiO2 using TiO2–P25 as a Ti precursor was investigated for the degradation of methylene blue under visible light irradiation. Urea and ethylenediamine (EDA) were evaluated as nitrogen sources. The produced photocatalysts had a rod-like nanostructure with the formation of mesopores. The resulting phase was a heterojunction of anatase, TiO2(B), and rutile, which enhanced charge separation. The presence of nitrogen during the hydrothermal reaction altered the morphology of TiO2, impacting the crystallite size. The U photocatalyst (urea source) achieved the best result for visible light with prior adsorption, degrading around 11 % of methylene blue in 5 h. This shows that it is possible to obtain a photocatalyst with superior performance to TiO2–P25 under both ultraviolet and visible light. This study presents an efficient strategy for improving the optical response of TiO2 by using nitrogen during a hydrothermal reaction, which has potential for industrial applications.

Strontium ferrite oxide (Sr3Fe2O7) decorated TiO2 photoanode improves the photo-absorption and photoelectrochemical cell efficiency

In this study, a coating of strontium ferrite oxide (SFO), Sr3Fe2O7, on TiO2 demonstrated an enhancement in photoelectrochemical cell (PEC) performance. Pure TiO2 and SFO decorated TiO2 (SFO/TiO2) were synthesized using the hydrothermal method. The concentration of SFO precursor in this study varied between 0.5, 1.0, and 1.5 mmol. Most of the optimized SFO concentration showed the better Applied Bias Photon-to-current Efficiency than the pure TiO2. The structure, chemistry, and surface morphology of TiO2 and SFO/TiO2 materials were investigated using several techniques, including X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The UV–visible spectra revealed that SFO was able to reduce the energy band gap of pristine TiO2 from 3.09 to 2.55 eV. The photoluminescence spectroscopy displayed that almost SFO/TiO2 materials exhibited the lower recombination time than the pristine TiO2. Moreover, 1.0 mmol of SFO/TiO2 exhibited the highest photocurrent density, at approximately 12.5 μA/cm2, which was 12 times greater than pure TiO2. The Mott-Schottky analysis revealed the energy band edge of SFO and the TiO2 was well alignment. Therefore, SFO plays a crucial role in improving the photo-absorption efficiency of PEC cell. The enhanced PEC performance was achievable due to the materials’ tailored light response.

Study on Photocatalytic Properties of TiO2 with Special Morphology by Using Natural Template

The TiO₂ photocatalysts with special morphology were synthesized in this paper. The authors used malus micro malus leaves and in docalamus leaves as template, and tetrabutyl titanate (TBT)as Ti source. The special shaped TiO₂ photocatalysts have high photocatalytic activity because of its unique morphology and s tructure. The structure and morphology of TiO₂ were characlerized by XRD and SEM, respectively. The photocatalytic activities were examined by the photodegradation of methylene blue (MB) under ultraviolet light (λ=365nm) iradiation. The results indicated that the TiO2 photocatalyst,using indocalamus leaves as templates, exhibited better adsorption and photocatalytic performance in degrading MB than using malus micro malus leaves, when the amount of nitric acid was 20 mL and following heat treatment at 600 ℃.

Effect of current density on the morphology and electrochemical properties of nanotubular TiO2 for implant applications

This study focuses on investigating the influence of current density (i) (A/dm2) at values of 0.5 A dm−2, 1.0 A dm−2 1.5 A dm−2, and 2.0 A/dm2 on the surface structure of nanotubular titanium dioxide (TiO2) in an ethylene glycol solvent containing a certain amount of fluoride salt and water. The surface structure observed via FESEM images reveals that different current densities yield different nanotubular TiO2 structures, predominantly in the form of anatase TiO2 crystals. EIS and CV measurements indicate that at a current density of i = 1.5 A dm−2, the nanotubular TiO2 layer exhibits corrosion resistance performance up to 90.06% compared to the bare titanium (Ti) samples. Confocal laser scanning microscopy (CLSM) demonstrates enhanced attachment of BHK cells on anodized titanium surfaces compared to unmodified controls. These findings suggest that nanotubular TiO2 presents a biocompatible material with promising potential for biomedical implant applications.

Precursor-concentration-controlled Morphology of TiO2 Nanorod/Nanoflower Films for Enhanced Photoelectrochemical Water Splitting and Investigating Their Growth Mechanism

Titanium dioxide (TiO2) has been considered as one of the most promising photocatalysts for photoelectrochemical (PEC) water splitting. Therefore, numerous efforts have been devoted to improving its PEC water splitting performance. In this study, TiO2 nanorod/nanoflower (NRF) films with controlled morphology were synthesized on fluorine-doped tin oxide (FTO) glass substrates by following a facile one-step hydrothermal method. The TiO2 NRF films were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectrometer (EDS), and ultraviolet-visible (UV-Vis) spectrophotometer. FE-SEM showed that the TiO2 films are composed of a simultaneous growth of a primary layer of TiO2 nanorod arrays (NRAs) and a second layer of TiO2 nanoflowers (NFs). The proposed growth mechanism highlighted the influence of precursor concentration on nucleation sites, affecting the preferred crystallographic plane growth of rutile TiO2 and nanorod alignment on the FTO substrate. Intriguingly, TiO2 NRF films prepared with 1.0 mL of titanium butoxide exhibited a maximum photocurrent density of 3.58 mA.cm−2 at 1.23 V versus (vs.) the reversible hydrogen electrode (RHE), along with a maximum photoconversion efficiency of 0.69%. The enhanced photocurrent density and photoconversion efficiency were attributed to the optimum thickness in the range of 4.52-7.31 µm, which caused the film to be formed with a unique morphology of the primary layer with well-vertically aligned nanorods and the second layer of flowers consisting of numerous rods stacked on top of one another. This study demonstrates the importance of designing semiconductors with 1D nanorod/3D nanoflower structures as high-performance photoelectrodes for PEC water splitting. Copyright © 2024 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Morphological and Compositional Study of Nitrogen-TiO₂ Anchored Composite with Azo Dyes in a DSSC

The efficiency of Dye-Sensitized Solar Cells (DSSCs) heavily relies on the structural and morphological characteristics of the photoanode materials [1]. This study investigates the effects of Nitrogen on TiO2 and the subsequent anchoring with two different Azo dyes RP and VC, to evaluate their impact on DSSC performance [2]. A comprehensive analysis was conducted using Scanning Electron Microscopy (SEM) to study the surface morphology of pure TiO2, Nitrogen TiO2 (N-TiO2), and N-TiO2 composites with RP and VC Azo dyes [3]. Energy-Dispersive X-Ray Spectroscopy (EDS) provided insight into the elemental composition and confirmed the successful incorporation of nitrogen into the TiO2 structure. The SEM images reveal significant morphological differences between the pure and N-TiO2 samples, as well as changes induced by the azo dye anchoring [4]. The Nitrogen incorporation was found to increase surface roughness and enhance dye adsorption [5]. A comparative analysis of the N-TiO2 composite with RP and VC azo dyes highlights variations in dye distribution and surface coverage, which may influence light absorption and charge transfer efficiency. The findings provide valuable insights into the design of optimized photoanode materials, aiming to improve the photovoltaic performance of DSSCs [6].

Morphology and Structure of TiO2 Nanotube/Carbon Nanostructure Coatings on Titanium Surfaces for Potential Biomedical Application.

Titanium is the most used material for implant production. To increase its biocompatibility, continuous research on new coatings has been performed by the scientific community. The aim of the present paper is to prepare new coatings on the surfaces of the pure Ti Grade 2 and the Ti6Al4V alloy. Three types of coatings were achieved by applying anodization and chemical vapor deposition (CVD) methods: TiO2 nanotubes (TNTs) were formed by anodization, carbon nanotubes (CNTs) were obtained through a metal-catalyst-free CVD process, and a bilayer coating (TiO2 nanotubes/carbon nanostructures) was prepared via successive anodization and CVD processes. The morphology and structure of the newly developed coatings were characterized using SEM, EDX, AFM, XRD, and Raman spectroscopy. It was found that after anodization, the morphology of the TiO2 layer on pure Ti consisted of a "sponge-like" structure, nanotubes, and nano-rods, while the TNTs layer on the Ti alloy comprised mainly nanotubes. The bilayer coatings on both materials demonstrated different morphologies: the pure Ti metal was covered by a layer of nanotubular and nano-rod TiO2 structures, followed by a dense carbon layer decorated with carbon nanoflakes, and on the Ti alloy, first, a TNTs layer was formed, and then carbon nano-rods were deposited using the CVD method.

Computational and experimental investigation of the structure, morphology, optical and electrical properties of TiO2 and caffeine adsorbed TiO2 in methyl ammonium lead iodide

Effects of caffeine and titanium dioxide (TiO2) in methylammonium lead iodide (MAPbI3/CH3NH3PbI3) as a photon absorber are studied. XRD showed high crystallinity of TiO2:Caffeine:MAPbI3 with larger crystallite size of ∼3.9 nm compared to TiO2:MAPbI3 with ∼3.6 nm. Large grain size of ∼550 µm was obtained for TiO2:Caffeine:MAPbI3 compared to ∼256 µm of TiO2:MAPbI3. Rod-like structures were observed though TiO2:Caffeine:MAPbI3 morphology and was smoother compared to TiO2:MAPbI3. Reduced bandgap energy of ∼2.3 eV was observed from TiO2:Caffeine:MAPbI3 and PL quenching indicated the possibility of reduction of the electron-hole recombination. TiO2:Caffeine:MAPbI3 showed better electrical conductivity compared to TiO2:MAPbI3. Density functional theory calculations showed increased charge transfer/redistribution which accounts for the slight enhanced electrical conductivity for TiO2:Caffeine:MAPbI3. The density of state calculations suggests the formation of unoccupied states and O 2p, Ti 3p, N 2p and C 2p as major contributors to the electronic and electrical properties of TiO2:Caffeine.

Efficient flexible dye-sensitized solar cells from rear illumination based on different morphologies of titanium dioxide photoanode

The TiO2 with nanoparticles (NPs), nanowires (NWs), nanorods (NRs) and nanotubes (NTs) structures were prepared by using a in-situ hydrothermal technique, and then proposed as a photoanode for flexible dye-sensitized solar cell (FDSSC). The influences of the morphology of TiO2 on the photovoltaic performances of FDSSCs were investigated. Under rear illumination of 100 mW·cm−2, the power conversion efficiencies of FDSSCs achieved 6.96%, 7.36%, 7.65%, and 7.83% with the TiO2 photoanodes of NPs, NWs, NRs, and NTs and PEDOT counter electrode. The FDSSCs based on TiO2 NRs and NTs photoanodes have higher short circuit current densities and power conversion efficiencies than that of the others. The enhanced power conversion efficiency is responsible for their nanotubes and rod-shaped ordered structures, which are more beneficial to transmission of electron and hole in semiconductor compared to the TiO2 nanoparticles and nanowires disordered structure.

MoS2 thin film decorated TiO2 nanotube arrays on flexible Ti foil for solar water splitting application

MoS2/TiO2 nanostructure provides a lot of advantages in photoelectrochemical (PEC) applications due to the absorption of the wide spectrum solar radiation, more catalytically active sites, proper band alignment, and better separation of photogenerated charge carriers. Here we report PEC water splitting studies of MoS2 thin film grown by chemical vapor deposition on TiO2 nanotubes fabricated on flexible thin Ti foil. Raman and x-ray diffraction analysis confirmed the polycrystalline growth of a few layers MoS2 on TiO2/Ti through their characteristic peaks. Field emission scanning electron microscopy revealed the nanotube surface morphology of TiO2 having a diameter in the range of 200–300 nm. The chemical and electronic composition of MoS2 and TiO2 were investigated by x-ray photoelectron spectroscopy. PEC measurements performed in 0.5 M Na2SO4 aqueous electrolyte solution under 100 mW cm−2 (AM 1.5G) simulated sunlight revealed 2-fold improved photocurrent density for MoS2/TiO2 heterostructure (∼135.7 μA cm−2) compared to that of bare TiO2 (∼70 μA cm−2). This is attributed to extended light absorption and more catalytically active surface area resulting from MoS2 functionalization of the TiO2 nanotubes, which results in better PEC activity. This study provides a new insight to explore the performance of thin metal foil-based photoelectrode in PEC applications that can be beneficial to develop roll-to-roll device fabrication to advance futuristic flexible electronics.