Photocatalytic Activity Of TiO2 Nanoparticles Research Articles

Antibacterial, antifungal, antiviral, and photocatalytic activities of TiO2 nanoparticles, nanocomposites, and bio-nanocomposites: Recent advances and challenges

The applications of nanomaterials specifically metal and metal nanoparticles in various medical and industrial fields have been due to their unique properties compared to bulk materials. A combination of pharmacology and nanotechnology has helped the production of novel antimicrobial agents to control resistant microorganisms of bacteria and fungi. The properties of metal nanoparticles and metal oxides such as titanium dioxide (TiO2), zinc oxide (ZnO), silver (Ag), and copper (Cu) are well known as efficient antimicrobial agents. In particular, TiO2 nanoparticles have been considered as an attractive antimicrobial compound due to their photocatalytic intrinsic and their stable, non-toxic, inexpensive, and safe physicochemical properties. Therefore, in this review, recent advances and challenges of antibacterial, antifungal, antiviral, and photocatalytic activities of TiO2 nanoparticles, nanocomposites, and bio-nanocomposites are presented to help future studies.

Eco-friendly mechanochemical synthesis of titania-graphene nanocomposites for pesticide photodegradation

Titania graphene hybrid nanocomposites (TiO2-FLG) synthesized from graphite and TiO2 precursors, in a simple and sustainable approach via a three-step method, including the mechanochemical treatment of pre-synthesized FLG and TiO2 NPs are efficient has led to the preparation of TiO2-FLG as efficient nano-catalysts for photocatalytic degradation of a complex mixing of pesticides (isoproturon, pyrimethanil, alachlor and methomyl). The effect of few layer graphene (FLG) loading (0–1.0%) was analyzed to define the optimal ratio of FLG to TiO2 and compared with the corresponding physical mixtures. X-ray Powder Diffraction (XRD) patterns of all these hybrid photocatalysts have presented the same crystal structure, with anatase as the main crystalline phase and brookite as secondary phase. An interaction between the graphene structure and the TiO2 nanoparticles has been observed from Energy Dispersive X-Ray (EDX), X-ray photoelectron (XPS) and Raman spectroscopy studies, indicating that FLG is mainly deposited on the surface wrapping the TiO2 nanoparticles. The presence of FLG in low concentrations and the mechanochemical activation are the key steps to improve the photocatalytic activity of TiO2 nanoparticles on these hybrid nanocomposites. The TiO2-FLG-0.5% hybrid nanocomposite, with circa 1.9 % content of graphitic carbon in surface, has showed the best photocatalytic performance in the degradation of pesticides. Pesticides were completely removed at 350 min, and around 82 % of total organic carbon (TOC) conversion was achieved at 540 min of irradiation time.

Simultaneous adsorption-photocatalytic treatment with TiO2-Sep nanocomposites for in situ remediation of sodium pentachlorophenol contaminated aqueous and soil

Sodium pentachlorophenol (NaPCP) is a highly toxic and persistent organic pollutant. With sepiolite as the support, a series of TiO2-Sep nanocomposites (NCs) with different Ti/Sep ratios were developed. The objective was to understand the effect of Ti/Sep ratio on the structure and activity of the NCs in aqueous and soil systems and to evaluate the feasibility of the NCs for in situ soil remediation. The prepared NCs were characterized with XRD, SEM, TEM, and N2 adsorption-desorption, respectively. The results showed that high surface area and good dispersion of TiO2 on sepiolite surface were obtained. The photocatalytic activities in aqueous and soil of the as-developed NCs were examined using NaPCP as a model pollutant. Compared with bare sepiolite and TiO2, the heterogeneous NCs showed significantly higher photocatalytic performance in decomposing NaPCP, and the photocatalytic activities varied with the content of TiO2 in the NCs. In aqueous media, treatment with TiO2-S-30 showed excellent degradation efficiency with about 90% NaPCP decomposed in 140min. Nevertheless, the sample TiO2-S-20 promotes maximum rate reduction of NaPCP with above 90% within 20-h irradiation in soil. The results indicate that an appropriate Ti/Sep ratio could significantly enhance the activities of NCs on NaPCP remediation and the role of carrier sepiolite is more important in soil media than that in aqueous phase. The excellent performance of the TiO2-Sep in wastewater degradation and soil remediation can be attributed to the synergistic effects between the high photocatalytic activity of TiO2 nanoparticles and the strong adsorption capacity of sepiolite nanofibers. This work revealed that sepiolite adsorption coupled with TiO2 photocatalysis can be one promising technique for in situ remediation of NaPCP-contaminated soil.

Effects of nitrogen/bismuth-doping on the photocatalyst composite of carbon dots/titanium dioxide nanoparticles (CDs/TNP) for enhanced visible light-driven removal of diclofenac

The present work demonstrates the coupling of titanium dioxide, TiO2 nanoparticles (TNP) with N-doped, Bi-doped, and N–Bi co-doped rice husk-derived carbon dots (CDs) via a facile dispersion method, forming respective photocatalyst composites of CDs/TNP, N-CDs/TNP, Bi-CDs/TNP and N–Bi-CDs/TNP. Characterization analyzes verified the successful incorporation of respective CDs samples into TNP, forming photocatalyst composite with narrowed band gap and quenched photoluminescence intensity. Photocatalytic activity of TNP and the respective composites was investigated for photodegradation of diclofenac (DCF) under both simulated sunlight and natural sunlight irradiation. The as-prepared N–Bi-CDs/TNP composite showed the best photocatalytic performance among all composites, able to completely degrade 5 ppm of DCF within 60 min and 180 min under both types of visible light irradiation, respectively. The N–Bi-CDs/TNP composite also showed a TOC removal efficiency up to 87.63%. N–Bi-CDs, worked as photosensitizer and electron reservoir, contributed to the outstanding photocatalytic activity of N–Bi-CDs/TNP, whereby the recombination was prolonged and light absorption was shifted towards the visible light region. Furthermore, the composite of N–Bi-CDs/TNP also demonstrated good stability and reusability over repeated degradation cycles. The photodegradation of DCF resulted into several intermediates, which were identified from LC-MS analysis. The present work could provide an insight on the application of heteroatoms doped and co-doped carbon dots in semiconductor oxide as high performance photocatalysts.

Investigation of photocatalytic activity of TiO2 nanoparticles synthesized by sol–gel technique

Anatase phase TiO2 nanoparticles were synthesized by sol–gel method using titanium(IV) butoxide as a starting material. The pH of solution was maintained by adding HNO3 and NaOH. The obtained powder was heat-treated at 350 °C for 2 h. The XRD study shows that the crystalline size and crystallinity of samples increase with pH of solution. Raman spectra confirm the dominance of anatase phase of TiO2. Morphology study of samples was done by scanning electron microscope (SEM). The size of prepared samples was calculated by XRD and confirmed by TEM analysis. The energy bandgap was calculated by optical absorption spectra and it was found to decrease by increasing pH of the solution. The photodegradation activity of Indigo Carmine (IC) dye under visible light irradiation was carried out by synthesized TiO2 nanoparticles. The removal of Indigo Carmine dye and degree of mineralization after photodegradation were studied using HPLC and TOC analysis respectively.

Functionalized mesoporous silicas SBA-15 for heterogeneous photocatalysis towards CECs removal from secondary urban wastewater

The photocatalytic activity of TiO2 nanoparticles (NPs) supported on mesoporous silica SBA-15 (TiO2/SBA-15) was evaluated for the photodegradation of sulfadiazine (SDZ), as target contaminant of emerging concern (CEC), using either pure water solutions (PW) or a real secondary urban wastewater (UWW) spiked with SDZ. For this purpose, TiO2/SBA-15 samples with 10, 20 and 30% TiO2 (w/w) were prepared by the sol-gel post synthetic method on pre-formed SBA-15, using titanium (IV) isopropoxide as a precursor. The TiO2/SBA-15 materials were characterized by HRTEM, SAXS and XRD, nitrogen adsorption isotherms and UV–vis diffuse reflectance spectroscopy. TiO2 NPs were shown to be attached onto the external surface, decorating the SBA-15 particles. The TiO2/SBA-15 catalysts were active in SDZ photodegradation using the annular FluHelik photoreactor, when irradiated with UVA light. The 30% TiO2/SBA-15 sample presented the best performance in optimization tests performed using PW, and it was further used for the tests with UWW. The photocatalytic activity of 30% TiO2/SBA-15 was higher (56% SDZ degradation) than that of standard TiO2–P25 (32% SDZ degradation) in the removal of SDZ spiked in the UWW ([SDZ] = 2 mg L−1). The photodegradation of SDZ with 30% TiO2/SBA-15 eached 90% for UWW spiked with a lower SDZ concentration ([SDZ] = 40 μg L−1). Aside of SDZ, a suit of 65 other CECs were also identified in the UWW sample using LC-MS spectrometry. A fast-screening test showed the heterogeneous photocatalytic system was able to remove most of the detected CECs from UWW, by either adsorption and/or photocatalysis.

Synergetic photocatalytic-activity enhancement of lanthanum doped TiO2 on halloysite nanocomposites for degradation of organic dye

A reusable and efficient photo-catalyst based on halloysites (HNTs) and La3+ ion-doped TiO2 nanoparticles was prepared using a sol-gel process and a sonochemical method for decomposing organic dyes. As a support, the HNTs increased the adsorption efficiency of substrates, improving the photocatalytic activity of TiO2 nanoparticles by ∼3 times. The La3+ ion doping of TiO2 decreased the bandgap from 3.25 eV to 3.01 eV, expanding the spectral response to the visible region and enhancing the photocatalytic activity under the sunlight by 1.5 times. Through the integration of the halloysite support and the La3+ ion doping of TiO2, the synergistic enhancement of photocatalytic activity was observed and systematically investigated using XRD, Raman spectroscopy, FT-IR, FE-SEM, EDX-TEM, and zeta potential. In this research, we used Rhodamine B molecules as a model pollutant. During the decomposing process, the HNTs enhanced the local dye concentration nearby the photo-catalyst through the electrostatic interaction, thereby boosting the photocatalytic activity by ∼3 times. Additionally, the catalyst can be separated by simple centrifugation and reused at least five recycles without any activity decrease. The halloysite support, the La3+ ion doping of TiO2 and their simple synthesis approach could provide a practical tool for environmental purification in wastewater using sunlight.

Photocatalytic Hydrogen Evolution Over Pt/Co-TiO2 Photocatalysts

Aims: In this study, the photocatalytic hydrogen evolution reaction from aqueous methanol was investigated upon simulated solar light using platinum loaded on cobalt doped TiO2 (Pt/Co-TiO2) composites. Background: Controversial results of cobalt-based composites create doubts about their photocatalytic activity. Thus, cobalt doped TiO2 composites were synthesized differently, and the photocatalytic activity was examined for the photocatalytic hydrogen generation. Objective: The current study aims to investigate the influence of cobalt doping and platinum loading on the photocatalytic activities of TiO2 nanoparticles for the photocatalytic H2 generation. Methods: The 0.5 wt.% Co-TiO2 and bare TiO2 photocatalysts were synthesized using two different methods, namely, reflux and hydrothermal synthesis. Additionally, the Pt deposition on the prepared Co-TiO2 and TiO2 catalysts (1 wt.% Pt) was performed using a photo-platinization method. : The as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy/ energy dispersive X-ray analysis (SEM/EDX), transmission electron microscopy (TEM), ultraviolet- visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and electrochemical impedance spectroscopy (EIS). Result: The XRD and EPR studies clearly indicated that the Co was incorporated into the titanium dioxide lattice. The EIS results suggested that the reduction of protons over Co-TiO2 and bare TiO2 materials was possible from a thermodynamic point of view. However, the photocatalytic results revealed that the formed amount of H2 was extremely low and close to the detection limit. The evolution of H2 from aqueous methanol (10 vol%) showed higher rates when employing 1 wt.% Pt loaded on 0.5 wt.% Co-TiO2 photocatalysts under simulated solar light irradiation. A maximum of 317 ± 44 μmol.h-1 was observed over the Pt/Co-TiO2-HT photocatalyst. Conclusion: EPR results confirmed that the cobalt ions were introduced into the TiO2 lattice by trapping the photogenerated conduction band electrons and decreasing the defects in the crystal cell. The Mott−Schottky analysis of electrochemical impedance measurements showed that all catalysts were ntype semiconductors and that cobalt doping induces impurity level within the band gap of TiO2. The experimental results of photocatalytic H2 generation from methanol-reforming demonstrated that no significant impact of Co-doping on the photocatalytic H2 formation was observed neither for bare TiO2 samples nor for the platinized materials. Based on these experimental findings, a possible mechanism for the continuous photocatalytic activity of Pt/Co-TiO2 photocatalysts under simulated solar light was proposed.

Sunlight mediated enhanced photocatalytic activity of TiO2 nanoparticles functionalized CuO-Cu2O nanorods for removal of methylene blue and oxytetracycline hydrochloride

Metal free heterojunctions have shown promising applicability as potential photocatalyst materials. Like the commonly explored metal-non metal heterojunctions, semiconductor-semiconductor junctions are also capable of facilitating charge separation and improved lifetimes, leading to augmented surface reaction efficacy. However, unlike the metal carrying heterojunctions, they are much economical and easier to fabricate and tune. Through this study, we present a facile one step hydrothermal route to synthesize CuO-Cu2O nanorods/TiO2 nanoparticles heterostructures (CTHS) with their potential application as a low cost photocatalytic alternative. The average size of the synthesized heterojunction components, as estimated from transmission electron microscopy (TEM) evaluation was 13 and 5 nm respectively for the nanorod length and width, while the functionalizing TiO2 nanoparticles were averaged around 10 nm. Heterojunction formation was confirmed using Raman spectroscopy, X-ray diffraction, high resolution TEM, and elemental mapping. X-ray photoelectron spectroscopy data marked with presence of Cu+ and Cu+2 state of CuO in CuXO-TiO2 also supported junction formation. Optical characteristics of the heterojunction were studied using UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. Compared to TiO2 nanoparticles, CTHS exhibited superior sunlight-induced photodegradation activity. CuXO/TiO2 heterojunction could also remediate toxic waste water containing model antibiotic residue (Oxytetracycline hydrochloride, 0.4 mg/mL) and organic pollutant (methylene blue, 10 µM) in 20 and 60 min respectively. Ultra-fast degradation using a nonmetal heterojunction nanohybrid, like ours, finds negligible mention in literature. Improved visible light absorption and reduction in recombination rate for CuXO-TiO2 nanohybrids were ascribed as major contributing factors towards their enhanced photocatalytic potential. The charge separation mechanism for nanohybrids has been studied and elaborated in detail.

The role of lanthanum in improving the visible-light photocatalytic activity of TiO2 nanoparticles prepared by hydrothermal method

In this work, the La-doped TiO2 (La–TiO2) nanoparticles with different La content were successfully synthesized by hydrothermal method aiming at enhancing the visible-light photocatalytic performance. The as-prepared photocatalysts were characterized by XRD, BET, TEM, XPS, FT-IR, photocatalytic performance and photo-electrochemical analysis. The experimental results indicate that La doping could suppress the phase transformation and hinder the crystallite growth of TiO2. Compared with other samples, the 1.5% La–TiO2 displays the highest photocatalytic activity under visible light, attributing to the synergic effect of the larger specific surface area and better separation capability of photo-generated holes and electrons. In addition, 1.5% La–TiO2 exhibits the outstanding recycling performance, and the degradation efficiency of the fifth day falls by 6.34% compared with the first day.

Application of TiO2 Nano-particles to incorporate Self- Cleaning in Polyester Fabric with the Help of Binder and to Study Changes in Physical Properties

The study aims at application of Nano scaled titanium dioxide nanoparticles with photocatalytic activity. The titanium dioxide nanoparticles were applied by a dip-pad–dry-cure process with the help of binders to textile materials for producing photocatalytic self-cleaning thin films. The study was focused on the application and characterization of titanium dioxide. The photocatalytic activity of TiO2 nanoparticles was studied against Methyl Orange degradation test in solar box test instrument by dissolving TiO2 nano-composites in an aqueous solution at low temperature. Polyester is most widely used synthetic fibre in textile and clothing. In this study, Anatase TiO2 nanoparticles are dispersed at room temperature via Sonication and treated polyester fabrics exhibit significant photocatalytic self-cleaning properties of degradation of coffee stains. The mechanical properties like bending length, breaking strength, air permeability and durability of TiO2 treated polyester fabrics were accessed. The study discovered that anatase TiO2 based self-cleaning system shows potential systems for self-cleaning textiles having high potential in commercialization being environmentally affable, energy and water saving, low cost as of reduced laundry cycles of the finished textiles.

Formation of TiO2 nanostructures modified Eumelanin films with enhanced properties for biopolymer implementations

Thin films of hybrid melanin-TiO2 nanoparticles (eumelanin: TiO2) deposited from solution by electro-spray were accurately inspected to unveil modified structural and electronic properties for device implementations. Based on the reorganization of the melanin electronic valence orbital, among other interesting behaviors, we observed up to a two orders increase in the absorption coefficient in the visible range. Furthermore the red-shifted absorption features, disclose that the extended π- stacking of oligomers is mainly responsible for the tunability of the optical gap as confirmed by photoluminescence. TiO2 nanostructures via oxidative polymerization, further improve the oligomeric character observed by means of Raman scattering. Finally, the photocatalytic activity of TiO2 nanoparticles helps the saturation of shallow trap states in melanin structure and consequently enhances the charge carrier transport.

Tuning the photocatalytic activity of TiO2 nanoparticles by ultrathin SiO2 films grown by low-temperature atmospheric pressure atomic layer deposition

We employed atomic layer deposition (ALD) to deposit ultrathin SiO2 layers on P25 TiO2 nanoparticles to fabricate TiO2/SiO2 core/shell nanostructures. The ALD process was carried out in a fluidized bed reactor working at atmospheric pressure using SiCl4 and H2O as precursors, enabling the deposition of SiO2 at 100 °C with the ability to control the thickness at the sub-nanometer level. By controlling the thickness of the SiO2 in a very narrow range, i.e., below 2 nm, the photocatalytic activity of TiO2 can be tuned. In particular, an enhancement was obtained for the SiO2 layers with a thickness below 1.4 nm, in which the layer with a thickness of about 0.7 nm exhibited the highest photocatalytic activity; for SiO2 layers thicker than 1.4 nm, the photocatalytic activity was strongly suppressed. The photocatalytic activity enhancement and the degradation mechanism of RhB by the TiO2/SiO2 photocatalysts were investigated by combining X-ray photoelectron spectroscopy, UV–Vis absorption spectroscopy, photoluminescence spectroscopy and the aid of charge carrier and radical scavengers. Our findings have revealed an improvement of photogenerated charge separation due to the SiO2 coating and the dominating role of hydroxyl radicals in the degradation of RhB.

Photocatalytic landfill leachate treatment using P-type TiO2 nanoparticles under visible light irradiation

Landfill leachate treatment is a necessary measure for environmental protection and supporting sustainable development. Photocatalytic treatment method using N- or P-type TiO2 nanoparticles has been proposed as an efficient method for the treatment of recalcitrant pollutants. Since main oxidizing agents in the photocatalytic treatment by N- and P-type TiO2 are different, investigating their performance for the photocatalytic treatment of landfill leachate is necessary. Therefore, the purpose of this study is to evaluate the performance of P-type TiO2 nanoparticles for the photocatalytic treatment of landfill leachate under visible light irradiation. Silicon (Si) element was considered as TiO2 dopant, and Si-doped TiO2 nanoparticles were synthesized by sol–gel method. Four effective parameters on the photocatalytic treatment process, i.e., the dopant content of Si (Si wt.%), calcination temperature (T), pH, and exposure time, were considered as independent variables, and temporal normalized concentration of leachate residual COD was considered as dependent variable. Decision tree (M5P) model was applied for modeling the photocatalytic process of landfill leachate treatment using the data of 167 experiments. Based on the results, the optimum value of pH, calcination temperature, and dopant content for Si-doped TiO2 nanoparticles are 6, 500 °C, and 2.5 weight percentage, respectively, and the leachate COD removal efficiency at these conditions is about 85% for leachate with 600 mg/L initial COD. Therefore, Si dopant considerably enhances the photocatalytic activity of TiO2 nanoparticles under visible light irradiation. This photocatalytic process can be efficiently applied for landfill leachate treatment. Finally, the performance of Si-doped TiO2 nanoparticles as P-type TiO2 was compared with the performance of tungsten (W)-doped TiO2 nanoparticles as N-type TiO2 for leachate COD removal. Results showed that both types of nanoparticles have a similar performance for oxidizing the leachate COD, and there is no significant difference between them.

Microwave plasma assisted sol-gel technique for synthesis of TiO2 nanoparticles

Titanium dioxide (TiO2) nanoparticles have attracted the attention of research community due to their novel functionalities as compared to the bulk material. TiO2 is an excellent photocatalyst due to its high photosensitivity, nontoxicity, high refractive index, strong oxidizing ability, high stability, wide band gap and high resistance to photochemical. The main objective of this study was to investigate the influence of microwave (MW) plasma treatment on TiO2 nanoparticles synthesized using sol-gel method. TiO2 nanoparticles were obtained through sol-gel method at ambient temperature. The suspension was heated at 300 °C for 2 hours to evaporate the organic content. The obtained nanoparticles were placed in partially vacuumized chamber for MW plasma treatment. The plasma treatment is a promising technique for oxidation of nanomaterials. Both plasma treated and untreated samples were evaluated with X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Visible spectroscopy for crystallite size, crystal phases, band gap energy and surface morphology. The obtained results confirmed the existence of anatase and rutile phases of TiO2 with smaller particle size within the range of 0.2 to 14 nm. The particles were of aggregated and trigonal shapes. The MW Plasma treatment improved the photocatalytic activity of TiO2 nanoparticles by raising their band gap energy and reducing the grain size.

Preparation and characterization of TiO2 nanoparticles by two different precipitation methods

This paper describes the structural and photocatalytic studies of TiO2 nanoparticles prepared by two different precipitation methods using titanium tetrachloride (TiCl4) and titanium oxalate [Ti(C2O4)2] as raw materials for the first time. The samples were characterized by TG-DSC, XRD, TEM, EDS, SAED, UV–Vis, Raman, N2 adsorption-desorption isotherms, and XPS to investigate the effects of salt type and calcination temperature on the crystal structure, morphology, composition, energy band gap and photocatalytic activity of TiO2 nanoparticles. Results indicated that when TiCl4 was used as Ti source, the crystallization temperature of amorphous TiO2 to anatase TiO2 was as low as 250 °C, but it increased to ~450 °C when Ti(C2O4)2 was selected. Besides, TiCl4 was able to dynamically modify the crystalline structure of TiO2 nanoparticles from anatase into rutile after calcination at ~450 °C, however this temperature was increased to ~850 °C for Ti(C2O4)2. The optimal photocatalytic property of methyl orange (MO) degradation in two TiO2 systems was 99.08% and 38.6% with corresponding calcination temperatures of 450 °C and 550 °C, respectively, which was mainly correlated with the different crystal structure and crystallite size.

Photocatalytic removal of airborne indoor pollutants by IR illuminated silver coated TiO2 catalyst: Advantage of one-dimensional TiO2 nanostructures in IR active photocatalysis

The development of IR sensitive photocatalysts is indispensable for the abatement of indoor pollutants as most of the photocatalysts mainly absorb radiation in the UV region and weakly in the visible region and not responding to indoor conditions. On the other hand, IR photons initiated photochemical reaction needs a highly efficient excited charge separation step as it is a multi-excitation process. In order to enhance the charge separation process in multi-step excitation photocatalytic systems, in this investigation the photocatalytic activities of silver coated 1-D TiO2 nanotubes were employed and the photocatalytic activity of 1-D TiO2nanotubes was compared with the photocatalytic activity of TiO2 nanoparticles. A superior photocatalytic activity was noted with the silver coated 1-D TiO2 nanotubes under IR irradiations than that of silver coated TiO2 nanoparticles. The impedance measurements were conducted by electrochemical impedance spectroscopy to differentiate the transport resistances, electron-hole recombination and electron lifetime of the silver coated 1-D TiO2nanotubes and nanoparticles. The possibility of the use of silver coated 1-D TiO2 nanotubes for the degradation of common airborne pollutants with near IR photons (similar to indoor conditions) was successfully demonstrated.

Synthesis, characterization and study of photocatalytic activity of TiO2 nanoparticles

Nanoparticles of TiO2 have attracted significant interest due to their special properties and have attained a great importance in several technological applications such as photocatalysis, sensors, solar cells and memory devices. Titania commonly exists in anatase (tetragonal), brookite (orthorhombic) and rutile (tetragonal) phase. In the present work, TiO2 nanoparticles of rutile phase were prepared by a simple chemical precipitation method using titanium tetra isopropoxide as a precursor. The band gap of the nanoparticles of TiO2 was calculated from the UV–Visible absorption spectrum and was found to be 3 eV which was less compared to bulk TiO2. The photocatalytic activity of TiO2 nanoparticles was studied on photo degradation of methylene blue and observed that methylene blue was degraded with increase in time.

Protective stainless steel micropillars for enhanced photocatalytic activity of TiO2 nanoparticles during wear

Enhanced photocatalytic activity of liquid flame spray (LFS) deposited TiO2 nanoparticles under tribological wear was investigated on metal injection molded (MIM) stainless steel substrates having micropillars as the load carrying support. A combination of LFS with MIM microtextures on the surface is a simple and cost-efficient way for manufacturing efficient photocatalytic substrates. Computer controlled microworking technique in combination with MIM was used to produce stainless steel micropillar surfaces that were functionalized by the LFS deposition of photocatalytically active TiO2 nanoparticles. The photocatalytic activity was measured in gas-phase with an in-house built photoreactor. Our results show that micropillars with controlled spacing we can control the surface area and increased photocatalytic activity of the micropillar substrate was observed compared to flat reference. The wear test confirmed that micropillars not only increase the surface area but they also provide protective support against wear whereas flat reference substrate lost the photocatalytic activity completely during wear.

Assessing the adsorption and photocatalytic activity of TiO2 nanoparticles for the gas phase acetaldehyde: A computational and experimental study

Herein, we report the photocatalytic activity of TiO2 NPs for the photodegradation of gas-phase acetaldehyde. TiO2 NPs with different morphologies were synthesized by using a hydrothermal method, which display distinctive dominant facets, including {001}, {101}, and {010}. The specific surface area values of TiO2 NPs showing different dominant facets, i.e., {001}, {101}, and {010} being measured as 92, 43.45, and 19 m2g-1, respectively. A 100% photodegradation efficiency (PE) could be achieved with TiO2 {001} NPs for 500 ppm acetaldehyde with a flowing rate of 10 sccm, while those of TiO2 NPs with dominant {101} and {010} facets exhibited low PE such as 83% and 62%, respectively. The first principle calculation revealed that acetaldehyde molecule strongly adsorbs (Eads = 0.606 eV) on TiO2 (001) surface while only weakly interacts with TiO2 (101) and (010) surfaces. We calculated the bandgap values of TiO2 NPs with different exposed facets, i.e., {001}, {101}, and {010} facets as 3.26, 3.23, and 3.21 eV, respectively. As an innovative exploration, this study isolates the photocatalytic activity of TiO2 NPs with unique morphologies and exposed facets, which can be exploited for the development of a potential photocatalyst for the photodegradation of other VOCs.