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This study aimed to explore the synergistic mechanism of lignin chromophore modifications via UV treatment and to analyze the effects of mechanical treatments on LCNF properties for future uses. The procedure involved two steps: first, lignin's chromophore modification via UV illumination, and then the ball milling process was proceeded for 1 h, followed by high-intensity ultrasonic for 15–135 min. Characterization included preserved lignin content percentage, FTIR, UV–vis NMR, and color analysis for UV-modified samples, and to access the influence of mechanical treatment on LCNF samples further yield, zeta potential analysis, XRD, thermogravimetric analysis, atomic force microscopy, and scanning electron microscopy were performed. LCNFs S-120 demonstrated a zeta potential of −21.7 mV, indicating enhanced stability compared to the S-135 sample (−10.95 mV). The S-120 sample also showed the highest yield (74.02 %) and TGA at 391 °C. In XRD analysis, the S-120 sample demonstrated the highest CrI 64.3 %, than the S-15 sample (48.2 %). Preserved lignin in the LCNFs led to a slight reduction in crystallinity across all samples but improved thermal stability for all the prepared LCNFs samples. The UV and ultrasonication improved the homogeneity and durability of the LCNF samples, enabling a process that may be used to industries. [Display omitted] • UV and mechanical processes produce maximum lignin-rich cellulose nanofibrils. • Lignin chromophore modification and ultrasonication's effect on LCNFs were analyzed • LCNFs samples showed good zeta potential and thermal stability. [ABSTRACT FROM AUTHOR]

The wetness impregnation method was used to synthesize 0.1% CdSe/TiO 2 photocatalysts with different atomic molar ratios (90–10, 70–30, 50–50, and 30–70). These catalysts were characterized by XRD, SEM-EDX and mapping, TEM-EDS, UV–VIS spectroscopy, fluorescence spectroscopy, XPS, TPR, TPO, and TPD analyses. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) analyses were performed to examine the photocatalytic activity for photocatalytic fuel cells (PFCs) in glucose solution in the dark and under UV illumination. The characterization analyses revealed that anatase TiO 2 formed the catalyst and electronic structure and surface properties changed when doped with metal. The photocatalytic glucose electrooxidation (PGE) results demonstrate that the 0.1% CdSe(50-50)/TiO 2 catalyst has higher photocatalytic activity, stability, and resistance than other catalysts both in the dark (2.71 mA cm−2) and under UV illumination (7.20 mA cm−2). These results offer a promising new type of photocatalyst for PFC applications. • TiO 2 is the most common semiconductor used in photocatalytic applications. • Cd and Se are metals with quantum dot properties. • Wet-impregnation, the most widely used method in catalyst synthesis. • Glucose is an organic material containing high energy in its structure. [ABSTRACT FROM AUTHOR]

We observe enhancements of both conductive and dielectric properties under UV illumination by using a ferroelectric absorber, potassium tantalate niobate (KTa 1-x Nb x O 3 , KTN). The UV-generated electron-hole pairs weaken the intrinsic ferroelectric polarization while enhance the conductive property. The UV-induced heat effect causes the enhancement of the dielectric property. The results are further confirmed by the maximal rectification ratio which shows an opposite trend between the direct heating process and the UV illumination. Our results are useful for better understanding of ferroelectric properties under UV illumination and the development of new optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this work, a wide and highly sensitive chemiresistive sensor has been developed based on the AZO nanocolumn array film. This is meant for the room detection of H 2 O 2 under UV illumination. A cost-effective one step multi-layers growth process was adopted for the synthesis of the AZO nanocolumn array. The experimental studies were done by scanning electron microscopy (SEM), transmission and electron microscopy (TEM).Then X-ray diffraction confirmed that the AZO column array was closely packed, connected, vertically aligned, and polycrystalline, with a high surface area. This structure ensures better electrical conduction over random and separated nanostructures. The hall-effect measurement indicates that the AZO film was n-type, with high conductivity (3.60 × 103 Ωcm), high carrier density (11.3 × 1020cm−3) and with acceptable mobility (0.95 cm2/Vs). The x-ray photoemission spectroscopy suggests that the AZO film consists of a large amount of adsorbed oxygen-related species at the sheath layer of the thin-film, which is vital for sensors. By the UV light activation, sensors based on the AZO nanocolumn array exhibited enhanced H 2 O 2 detection properties at room temperature. At a concentration from 15 μM to 30 mM, H 2 O 2 sensitivity evaluated by relative response was remarkably increased from 15% to 36%. The operation under ambient conditions and wide range sensing shows that this chemiresistive AZO sensor is adequate for biomedical and environmental applications. [ABSTRACT FROM AUTHOR]

Chemiresistive gas sensors have been extensively explored for hazardous gas detection. Currently, an overwheming majority of previous attention was focused on the parameter improvement of sensor performance while the impact of carrier gas species on the performance was severely ignored. Aiming to a deep insight into this issue, in this work we prepared zinc oxide (ZnO) nanowire-network sensor and explored its UV-activated sensing performance toward trace nitrogen dioxide gas (NO 2) at room temperature (25 °C) under two carrier gases, i.e., dry nitrogen (N 2) and air. Within N 2 , the sensor exhibited a reversible response of 157 toward 50 ppb NO 2 and a sensitivity of 7.8/ppb, which was not only among the best showcases of the existing work, but much larger than those within air (11 and 0.091/ppb, respectively). Moreover, decent selectivity and long-term stability were demonstrated. Far more UV irradiation-induced electrons which reacted with adsorbed NO 2 molecules on ZnO surface as well as smaller baseline resistance under N 2 than those under air jointly led to the superior response and sensitivity. After long-time UV exposure prior to gas-sensing tests within both carrier gas cases, the remaining oxygen ions (O 2 −) were weakly bonded on ZnO surface, contributing to the reversible behaviors at room temperature. The interconversion between physisorbed O 2 molecules and ionic O 2 − on ZnO surface was proposed to rationalize the sensing phenomena especially when no continuous oxygen was supplied under N 2 atmosphere, which enriched the current transduction mechanisms. [ABSTRACT FROM AUTHOR]

Photocorrosion of a photocatalyst's surface, leading to degradation of its catalytic efficiency/cyclability, is a major concern which must be tackled for designing efficient processes. Despite that the photocorrosion of ZnO has been widely explored, a deep understanding of the mechanism involved is still elusive. Here, a detailed investigation of the photocorrosion mechanism is presented. Controlled UV treatment of ZnO dispersions took place in the absence of pollutants. Employing advanced characterization techniques, we have elucidated the intricate pathways through which the photocorrosion takes place. Successive photocatalytic MB degradation cycles were performed using untreated ZnO nanocrystals to assess their photostability and reusability. It is shown that UV treatment up to 4 h, deteriorates the ZnO crystal which in turn diminishes its photocatalytic activity. For prolonged irradiation up to 8 h, an effective regeneration of the ZnO lattice takes place, reverting the photocatalytic activity to pristine levels. Understanding the photocorrosion mechanism could constitute the key in fabricating large-scale reusable photocatalysts that can be regenerated by UV light. [Display omitted] • Internal and external photocorrosion mechanisms are elucidated. • Prolonged UV treatment in the absence of pollutants leads to catalyst regeneration. • Photocorrosion pathways are explored by advanced surface characterization. • Surface composition determines the photocatalytic rate. [ABSTRACT FROM AUTHOR]

A reliable and high-performance oxygen (O 2) sensor based on TiO 2 -decorated bridging Gallium Nitride nanowires (TiO 2 /GaN NWs) was fabricated, which operates under ultraviolet (UV) irradiation at room temperature (RT). The TiO 2 /GaN NWs were prepared by direct-bridge growth of GaN NWs across the trench of GaN coated sapphire substrate, followed by titanium (Ti) sputtering and thermal oxidation. The morphology characteristic shows that TiO 2 nanoparticles (NPs) are anchored uniformly on the surface of GaN NWs. The sensors with various TiO 2 film thickness (0, 2, 5, 10 nm) were measured at RT under 365 nm UV illumination with O 2 concentrations varying from 1% to 25%. Experimental results show that when the TiO 2 film thickness is 5 nm, the O 2 response reaches its maximum and the limit of detection (LOD) as low as 0.45% O 2. Moreover, the 5 nm TiO 2 /GaN NWs sensor were also measured under different wavelengths (λ = 280, 365, 450 nm) UV illumination and found that the lower light wavelength, the higher O 2 sensing. In addition, the sensor has excellent repeatability, selectivity and long-term stability, thus has a wide application in the field of O 2 gas sensing. [Display omitted] • A oxygen gas sensor based on TiO 2 /GaN NWs was fabricated and well studied. • The sensor operates in air atmosphere under UV illumination (λ = 365 nm) at room temperature (∼25 ℃). • When the TiO 2 thickness is 5 nm, the O 2 response reaches its maximum and the limit of detection ∼ 0.45% O 2. • The sensor has excellent repeatability, selectivity and long-term stability. • Oxygen response under different UV wavelengths was also studied. [ABSTRACT FROM AUTHOR]

Massive free electrons in metals could escape from the metal surface to generate a convection current when colliding with high-energy photons (e.g. UV light). Namely, metals with specific work functions could transduce light energy into direct-current (DC) electricity via the famous external photoelectric effect. However, obtaining alternating-current (AC) electricity via a non-Faraday's law of electromagnetic induction directly using metal foil is challenging. Inspired by our recent work, we herein for the first time report a subtle method to directly transduce UV light energy into AC electricity by metal foil nanogenerators and propose a new mechanism regarding the transduction of UV light into AC electricity entitled the neglected internal photoelectric effect (NIPE). According to the NIPE, a zinc foil-based NIPE nanogenerator (NIPEG) can output an optimal open-circuit voltage (V oc) and a short-circuit current (I sc) of 108 V and 320 μA, respectively. The maximum output power and the photoelectric conversion efficiency of the fabricated nanogenerator approach 23.9 W m−2 and 77.02%, respectively. Meantime, the electrical energy stored in the capacitor connected to the Zn foil-based nanogenerator after rectification is several orders of magnitude higher than that of the conventional Cu/PTFE/PET/Cu-based triboelectric nanogenerator and Cu/PTFE/Al-based water droplet nanogenerator. The herein approach potentially offers a novel energy harvesting and conversion avenue to develop self-powered and wearable electronic devices. [Display omitted] • UV-light can be transduced into AC electricity using a metal foil nanogenerator. • A neglected internal photoelectric effect of metal foil is proposed. • The optimal V oc and I sc of the nanogenerator under UV reach 108 V and 320 μA, respectively. • The optimal output power and photoelectric conversion efficiency reach 23.9 W m−2 and 77.0%, respectively. • The energy stored in a 2200 μF capacitor is several orders of magnitude higher than typical TENGs. [ABSTRACT FROM AUTHOR]

Selectivity of the Zirconia-based amperometric gas sensors can be easily controlled via manipulating the applied bias voltage. Nevertheless, poor sensitivity and inadequate response signal hindered their research foreground. Recently, light-regulated electrochemical reaction has been confirmed to be helpful in improving the electrocatalytic activity of photoactive sensing materials, herein, we studied the impact of UV illumination on the sensing performance of zirconia-based amperometric gas sensor, with utilizing photoactive ZnO sensing electrode and Pt counter electrode (vs. Mn-based reference electrode). Through manipulating the applied bias voltage, the sensor demonstrates acceptable selectivity to C 3 H 6 against CO and NO. Moreover, after illuminated by UV light, response signal to all the examined hazardous gases is enhanced. Interestingly, relatively large enhancement is solely observed for sensing C 3 H 6 , leading to simultaneous improvements in the sensitivity and selectivity for the sensor operated upon illumination. These promising results shed light on an alternative strategy for artificially tailoring gas sensing characteristics via light-regulated amperometric gas sensors. [ABSTRACT FROM AUTHOR]

In this work, reduced graphene oxide (rGO)/GaN nanorods (NRs) hybrid structure based sensors for hydrogen (H 2 ) and hydrogen sulfide (H 2 S) gases has been demonstrated at room temperature. The morphological, elemental, and structural analyses were carried out by using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The electrical characterization of rGO/GaN NRs hybrid structures showed good rectifying behavior compared to pristine GaN NRs. The H 2 and H 2 S gas sensing measurements at different gas concentrations revealed that the rGO/GaN NRs exhibit superior sensing properties compared to pristine GaN NRs. In order to find the gas sensing mechanism of rGO/GaN NRs, hybrid structure sensor is also tested with NO x gas. Our experimental results revealed that the rGO/GaN NRs are good candidates for selective detection of H 2 S gas. The rGO/GaN NRs showed remarkably improved response under ultra-violet (λ = 365 nm) illumination, the photogenerated carriers could be responsible for increasing response of the gas sensor at 30 °C under UV illumination. In addition, humidity test of the rGO/GaN NRs sensor was also conducted in this work. Our experimental results suggested that decorating GaN NRs with solution-processable rGO is one of the effective ways to enhance the response of GaN nanostructures. [ABSTRACT FROM AUTHOR]

The aim of this work was to prepare, characterize and evaluate the potential of novel ZnO/stellerite composite photocatalysts against Staphylococcus aureus ( S. aureus ). SEM/EDS studies employed to study the surface morphological properties revealed stellerite as the catalysts carrier played a role of dispersant for ZnO nanoparticles. The XRD patterns of the ZnO/stellerite indicated hexagonal crystal structure with 20–30 nm size. It was found that the crystallite size of ZnO/stellerite was much smaller as compared to pure ZnO and increased with increasing ZnO loading amount. The results of optical properties of ZnO/stellerite showed smaller band gap in contrast to pure ZnO, investigated by UV–vis absorption. Due to the optimum ZnO loading, the as-prepared ZnO-20 composite had the highest BET surface area and the pore volume. Using the TG-DSC measurement, the high thermal stability of the product was studied for different temperature values. Antibacterial activity of ZnO/stellerite affected by the ZnO loading, concentration of samples and light conditions (under dark and UV irradiation conditions) was examined by disinfection of S. aureus . The as-prepared ZnO-20 composite with 100 mg/L was found to exhibit excellent inactivation efficiencies (87.65% in the dark and 97.67% under UV illumination) towards S. aureus. Compared with pure ZnO, the obtained composite photocatalysts showed significantly better antibacterial performance by studying the disinfection kinetics of S. aureus. Thus, the present study reveals that the novel ZnO/stellerite shows great potential for its use in the targeted disinfection applications. [ABSTRACT FROM AUTHOR]

As an n-type metal oxide semiconductor (MOS), vanadium pentoxide (V 2 O 5) has shown great potential in gas sensing, especially for the detection of NO 2. Herein, a highly sensitive NO 2 sensor based on 3D porous V 2 O 5 microrods (MRs) derived from metal organic frameworks (MOFs) was reported. The porous structure of vanadium-based MOF-derivatives (MIL-47) was tuned by the control of annealing temperature (300 °C–600 °C) in the pyrolysis process. The gas sensors with the MOF-derivatives are exposed to NO 2 at 150 ℃ for gas sensing tests. The sensor with MOF-derivatives annealed at 500 °C (MIL-47–500) showed the highest response (527 %) to 50 ppm NO 2. It also showed excellent selectivity, low limit of detection, and good repeatability. The NO 2 -sensing behaviors of the MIL-47–500 sensor under ultraviolet (UV) illumination have also been investigated. Under UV illumination, the response of the MIL-47–500 sensor increased to 706 %. At 75 °C, the response of the MIL-47–500 sensor toward 50 ppm NO 2 was significantly improved from 57 % to 538 % under UV illumination. The response/recovery times were reduced from 102 s/300–48 s/178 s. The excellent performance was attributed to the unique porous structure of MIL-47–500 and the UV light excited charge carriers. [Display omitted] • 3D porous V 2 O 5 were prepared by annealing vanadium-based MOF (MIL-47). • The microstructures of V 2 O 5 at different annealing temperature were studied. • The V 2 O 5 annealed at 500 ºC showed the high response of 527 % to 50 ppm NO 2. • Under UV, the properties of sensor are greatly improved at low temperature. [ABSTRACT FROM AUTHOR]

Low-frequency current noise measurements were performed on Mg-doped ZnO (MZO) nanorod photodetectors (PD), and 1/f noise was observed in both dark and under ultraviolet (UV) illumination. Results show that the average length and diameter of the nanorods were 609 nm and approximately 50 nm, respectively. The X-ray diffraction spectrum showed that the Mg-doped ZnO nanorods had a wurtzite hexagonal sturcture. The photoelectric properties of the nanorods were stable under UV illumination. The resulting Mg-doped ZnO nanorods had excellent potential for UV photodetector applications. Mg-doped ZnO nanorod UV photodetectors had a high UV-to-visible ratio and a fast rise/fall time. The dynamic response of the Mg-doped ZnO nanorod photodetector was stable and reproducible with an on/off current contrast ratio of approximately 4 × 10 3 . The UV-to-visible rejection ratio of the sample was approximately 400 when biased at 1 V, and the fabricated UV photodetector was visible-blind with a sharp cutoff at 350 nm. The low-frequency noise spectra obtained from the UV photodetector were caused by the 1/f noise. The noise-equivalent power (NEP) and normalized detectivity (D * ) of the Mg-doped ZnO nanorod PD were 3.35 × 10 −10 W and 1.49 × 10 8 cm Hz0.5 W −1 , respectively. Under UV illumination, the NEP and D * were 1.8 × 10 −6 W and 2.7 × 106 cm Hz0.5 W −1 , respectively. [ABSTRACT FROM AUTHOR]

An improvement in the response of a graphene-based acetone sensor is achieved by the combination of optimizing the spacing between the electrodes and UV illumination during the sensing measurement. A monolayer graphene membrane was grown on Cu foil by low pressure chemical vapor deposition, and then, it was transferred to an interdigitated electrode to achieve a resistive-type gas sensor. The response of the sensor to acetone was small without UV light illumination, but improved 7 times for an acetone concentration of 1000 ppb with UV illumination continuously applied during the measurement. In addition, the sensor response for a spacing of 400 μm was approximately 2X higher compared to that for a spacing of 50 μm for acetone concentrations of 100–1000 ppb. Furthermore, short-time UV illumination performed on these graphene-based sensors resulted in low power consumption and achieved similar results compared to continuous UV illumination. The origin of these improvements could be due to the reduction of hole carriers by oxygen and water molecule desorption from the graphene surface due to UV illumination. The surface area ratio of graphene on the glass showed a strong positive correlation to the acetone response and sensitivity, which could be related to the higher affinity in the unit sensing area. The substrate doping effect could be an important factor for the graphene-based gas sensors. [ABSTRACT FROM AUTHOR]

UV-B radiation (5, 10 and 15 kJ m − 2 ) treatments, single or combined with UV-C (9 kJ m − 2 ), were hereby firstly studied as bioprocessing tools to enhance bioactive compounds of broccoli byproducts (leaves and stalks) compared to edible florets during storage (72 h/15 °C). Leaves showed similar total phenolic content (TPC) and antioxidant capacity (TAC) than florets, and 2.5/14.5 higher glucoraphanin/glucobrassicin contents than florets. UV increased initial TPC and TAC of leaves/stalks up to 31–97/30–75 and 20–120/170–420%, respectively. UV-B10 + C induced the highest TPC increase (110%) in leaves while UV-B10 and UV-B10 + C led to the highest TPC of stalks after 48 h. UV-B10 + C increased (34%) glucobrassicin levels of leaves while UV-B15 and UV-B15 + C induced the highest glucoraphanin levels (131 and 117 mg kg − 1 ) in florets after 72 h. Conclusively, single or combined postharvest UV-B and UV-C treatments can revalorize such agricultural byproducts and also add value to edible broccoli parts. Industrial relevance This work demonstrates the high potential of the use of postharvest treatments with UV-B and UV-C, optimized as single or combined treatments, to be used as bioprocessing tools to enhance the bioactive compounds of broccoli byproducts (leaves and stalks) being compared to edible florets. Thought this innovative application of this technology such agricultural wastes may be highly revalorized with a cheap technology leading to high production of health-promoting compounds with such eco-sustainable technology whose benefits can be even reach to the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

A gas sensor to detect H 2 S gas based on SnO 2 nanorods (NRs) and Ag doped SnO 2 nanoparticles (NPs) was fabricated by growing SnO 2 NRs on an interdigitated Au substrate and spin coating Ag doped SnO 2 NPs on the NRs' surface. The morphology, chemical, optical, and electrical properties of this nanostructure were examined using FESEM, EDAX, XRD, PL and absorption spectroscopy. The fabricated sensor was further enhanced by doping the SnO 2 NPs with Ag as well as utilizing an innovative method of simultaneous exposure to UV illumination and self-heating. The proposed design has proven to reduce the destructive effect of humidity due to its photocatalytic properties. This unique nanostructure design enhanced the sensing response of the device from 2.7 to 8 (in the detection range of 500 ppb-10 ppm). This improvement caused by an increase of the electron injection on the NPs' interfaces and a multiplication of the available active sites on which H 2 S gas is trapped. In addition, the sensor's response and recovery time toward 10 ppm H 2 S gas increased from 11 and 14 s to 5 and 8 s respectively. The sensor's cross-sensitivity toward C 6 H 6 , C 2 H 5 OH, CO 2, and NH 3 was also examined to determine the selectivity. [Display omitted] • Simultaneous treatment of device with UV and self-heating enhances the sensing parameters. • Doping the nanostructure with Ag increased the receding of depletion layer and sensitivity. • Wielding the deteriorating effect of humidity as an amplifying factor for device efficiency. • The device exhibited remarkable selectivity when cross-tested in the presence of other gases. [ABSTRACT FROM AUTHOR]

To increase the ethanol sensing at low operating temperatures in ZnO nanostructure sensors, the gold nanoparticles were introduced to ZnO nanostructures (ZnO:AuNPs) by a sputtering technique. Then, the ethanol sensing characteristics were investigated under UV illumination at the temperatures in the range of 25–125 °C. It was found that the sensor response of ZnO:AuNPs sensor under UV illumination was remarkably improved. Moreover, the sensor based on ZnO:AuNPs under UV illumination exhibited the increasing of sensor response toward ethanol vapor with an increasing of UV illumination intensity from 0 to 4.1 mW/cm 2 . The sensor response enhancement mechanism can be explained by two main effects including sensor response enhancement due to an addition of AuNPs on ZnO nanostructures and UV illumination. The AuNPs added onto ZnO nanostructure strongly affect the chemical reaction change in the oxygen adsorption reaction resulting in a larger depletion layer width. As a result, the sensor response is enhanced to higher than that of ZnO nanostructure sensor. The sensor response enhancement due to UV illumination is explained by the formation of weakly bound oxygen ions from electron carriers being excited from band to band and oxygen molecule in air. This produces a thinner depletion layer width with the weakly bound oxygen ions due to the photo activation which are easily removed from the ZnO surface resulting in high sensor response with lower resistance. [ABSTRACT FROM AUTHOR]

UV activated metal oxides for chemiresistive-type gas sensors have been recently studied aiming to lower the working temperature and thus lower the power consumption. In this work, the mesoporous hollow ZnO microspheres were prepared by template-assisted method and examined for VOCs detection with UV LED illumination at lower temperatures than 150 °C. The as-synthesized ZnO based sensor indicated an excellent response and selectivity to different concentrations of ethanol (10–1000 ppm) with low-powered UV LED (2 mW) at 80 °C. The response time is only ∼6 s while the recovery is a little sluggish (∼94 s). The enhanced sensing performance could be attributed to the mesoporous hollow microstructure of the synthesized ZnO and UV activated differential photoctalytic oxidation reactions at the shallow oxide surface regions. The repeatability and long term stability of the sensor and the sensor response were also investigated. A comparison with the conventional thermal-activated gas sensing of the hollow ZnO was also conducted and the photo-activated gas sensing mechanism was discussed. [ABSTRACT FROM AUTHOR]

Bi 2 S 3 nanorods with orthorhombic structure were successfully synthesized through hydrothermal method. Systematic experiments were accomplished to study the variable factors such as the Bi/S molar ratio, reaction time and reaction temperature, which have great impact on the structural morphologies of Bi 2 S 3 and the photocatalytic performance. TEM and FE-SEM images reveal that the prepared Bi 2 S 3 is flower-like built up from many nanorods with average 30–50 nm in diameter and 0.5–1 μm length. The optimal conditions for the preparation of Bi 2 S 3 nanorods were Bi/S molar ratio 1/2 for 20 h at 180 °C to obtain the highest photocatalytic activity of ~ 98% towards methylene blue (MB) degradation. It is also found that the determined k values for Bi 2 S 3 nanorods prepared at Bi/S molar ratio 1/2 was higher 40 and 5.5 times than that the samples prepared at either low or high Bi/S molar ratios 1/0.5 and 1/5, respectively. [ABSTRACT FROM AUTHOR]

In this work, a simple strategy was used to prepare Ti 3+ surface defect states through the simple UV irradiation of TiO 2 nanotubes (TiNT) formed in ethylene glycol/NH 4 F/H 3 PO4/H 2 O mixture at different anodizing potentials. The band gap electronic states created by Ti 3+ are mostly responsible for the effective narrowing of band gap. The effect of anodizing potential on surface states of TiO 2 nanotubes/electrolyte interface has been studied under UV irradiation. A quantitative and qualitative analysis of surface states of TiNT formed at different anodizing potential was performed using capacitance measurements. These measurements allow us to provide evidence for the presence of monoenergetic surface states in the band gap. The energy levels and the density of surface states have been determined. Both density and energetic location are very dependent on the geometric characteristics. Relatively wide distribution of these states in a range of electric energy of 0.17–0.35 eV below the edge of the conduction band was obtained according to the anodizing potential. The optical absorption at 630 nm may be attributed to deep level states originated from oxygen vacancies associated with Ti 3+ . The presence of energetic level states and elevated surface solid fraction factor of TiNT are the determining factors in enhancing the photoactivity in visible light as evidenced by high photocurrent densities up to 16 mA cm −2 . [ABSTRACT FROM AUTHOR]

In this work, a novel gas sensor based on ZnO/silk fibroin (ZnO/SF), which was synthesized by the hydrothermal method, was proposed for efficient and fast detection of NO 2 gas under the irradiation of 365 nm UV-light at room temperature. The prepared ZnO/SF sensor activated by UV showed a high sensing response of about 85 towards 20 ppm NO 2 gas at room temperature with an average response and recovery time of 26 s and 16 s, respectively. Test results of 1 ppm, 5 ppm, 10 ppm, 20 ppm NO 2 gas indicated that the ZnO/SF sensor had a very excellent response and linearity. Additionally, the sensing mechanism was analyzed as well. [ABSTRACT FROM AUTHOR]

Ternary hybrid composites are less explored for gas sensing purposes due to their complexity of structures. However, their complexity brings about a greater potential for resistance changes. In this study, we have synthesized a new ternary hybrid composite composed of polyaniline (PANI)-loaded Co 3 O 4 -TiO 2 composite nanoparticles (NPs) for acetone sensing at 25 ℃. For this purpose, PANI and Co 3 O 4 were added into TiO 2 NPs using sol-gel method. The gas sensing characteristics of PANI-TiO 2 , Co 3 O 4 -TiO 2 composite NPs and PANI-loaded Co 3 O 4 -TiO 2 composite NPs sensors were systematically investigated with and without UV illumination (at 25 °C). Based on the sensing results, the ternary 0.01 wt% PANI-loaded 0.85TiO 2 − 0.15 Co 3 O 4 composite NPs revealed the highest response to acetone under UV illumination at 25 ℃. The enhanced performance of optimized gas sensor was due to formation of p-n heterojunctions, promising effects of PANI, and UV light effect. The results obtained herein, highlighted the possibility of making a highly reliable acetone sensor working at 25 ℃ using this compounds or related compounds. • Gas sensing properties of PANI-Co 3 O 4 loaded TiO 2 nanoparticles were examined. • Heterojunctions and adsorbed oxygen species contributed to the sensing enhancement. • Higher adsorption energy between acetone and TiO 2 improved the selectivity. [ABSTRACT FROM AUTHOR]

Room temperature chemoresistive gas sensors could significantly decrease the demand of power consumption and are thus highly desirable in self-sustained nanosensors. Here we report that chemoresistive sensors fabricated from mesoporous hollow TiO 2 microspheres show high sensitivity and selectivity to sub-ppm level of formaldehyde at room temperature with the assistance of low powered UV LED photon energy (2.5 mW). The sensor indicated excellent selectivity to other possible interferrents such as methanol, ethanol, acetone, ammonia and methylbenzene at low concentrations. These sensors have a much faster response (∼40 s)/recovery (∼50 s) characteristic, which significantly surpass the sensing properties shown by other types of nanostructured TiO 2 reported in literature. [ABSTRACT FROM AUTHOR]

In this study, chitosan coated Mn-doped ZnS quantum dots (CS@ZnS:Mn D-dots) were obtained in aqueous media under ambient pressure. The interaction and illumination damages of CS@ZnS:Mn D-dots with bovine serum albumin (BSA) were studied by means of ultraviolet–visible (UV–vis) and fluorescence (FL) spectra. It was found that the FL of BSA was quenched by CS@ZnS:Mn D-dots. The dominating quenching mechanism of CS@ZnS:Mn D-dots with BSA belongs to dynamic quenching. Hydrophobic interaction plays a major role in the CS@ZnS:Mn–BSA interaction; binding processes are spontaneous. Influencing factors such as illumination time and CS@ZnS:Mn D-dots concentrations were considered. The FL quenching effect of BSA by CS@ZnS:Mn D-dots is enhanced with the increase of illumination time and CS@ZnS:Mn D-dots concentration. The FL enhancement of CS@ZnS:Mn D-dots by BSA under UV illumination was also observed. It was proved that, the interaction of CS@ZnS:Mn D-dots with BSA under UV illumination is mainly a result of a photo-induced free radical procedure. CS@ZnS:Mn D-dots may be used as photosensitizers in photodynamic therapy. [ABSTRACT FROM AUTHOR]

An increasing number of studies have focused on controlling the boiling flow field using external effects. This study is the first to propose a transition of bubble nucleation by triggering titanium dioxide (TiO 2) surfaces with ultraviolet (UV) illumination during the pool boiling process. In the presence of UV light, the wettability of the TiO 2 surface changed from hydrophobic to hydrophilic owing to photocatalysis. An opportune moment to activate the surface wettability transition using UV illumination occurred during the boiling process of isolated bubbles. High-speed camera images showed that the transition of the surface wettability with UV illumination changed the liquid vapor dynamics in the pool and affected the boiling heat transfer performance. The TiO 2 -coated surfaces of the test samples, upon UV illumination, showed an enhancement of 72% in the critical heat flux (CHF) and 49% in the heat transfer coefficient (HTC) compared with plain copper surfaces. [ABSTRACT FROM AUTHOR]

This paper introduces a high-efficiency CO gas sensor based on ZnO/SnSe 2 composite film. The rod-shaped SnSe 2 and polyhedral ZnO composite nanostructures were prepared by template sacrificial method and solvothermal method. The developed composite material was characterized by scanning X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and I-V testing methods, and its microstructure and composition were explored. Through comparative experiments, it was found that the response of ZnO/SnSe 2 was the highest when the loading rate of SnSe 2 is 25%, which was superior to pure ZnO and SnSe 2 sensors. The ZnO/SnSe 2 composite sensor showed excellent selectivity and good dynamic characteristics to CO at room temperature (RT). To further improve the performance of the prepared CO sensor, we studied the effect of ultraviolet (UV) light on the sensor, and the research concluded that UV light can improve the gas-sensing characteristics of the sensors. The possible CO sensing mechanism is related to the heterostructure between n-type SnSe 2 and n-type ZnO nanomaterials and the photoelectrons excited by UV light. • The rod-shaped SnSe 2 and polyhedral ZnO composite nanostructures were prepared by template sacrificial method. • The ZnO/SnSe 2 heterostructures exhibited an enhancement of CO sensing properties at room temperature. • The sensing performances of ZnO/SnSe 2 to CO were significantly improved with the irradiation of UV light. [ABSTRACT FROM AUTHOR]

The UV-enhanced sensing performance of the two-dimensional polyimide/indium oxide (2DPI/In 2 O 3) based sensor towards NH 3 was investigated at room temperature of 25 °C. The 2DPI/In 2 O 3 composite materials with hydrogen bond were synthesized by hydrothermal method, which is sensitive to NH 3 in the absence or presence of UV illumination. The microstructure, morphology and constituent elements of the prepared samples were characterized by SEM, TEM, XRD, XPS, FT-IR and UV–visible analysis. The as-prepared 2DPI/In 2 O 3 based sensor shows the best sensing performance compared to those of pure 2DPI and pure In 2 O 3 sensors. In terms of the sensitivity of the 2DPI/In 2 O 3 based sensor, the synergistic effect between 2DPI and In 2 O 3 leads to an enhancement of three times response of the composite sensors under UV illumination compared with the response of composite sensors without UV illumination. Particularly, the response time and recovery time of the 2DPI/In 2 O 3 based sensor towards 1 ppm NH 3 are shortened by 10 s and 20 s under 365 nm UV illumination, respectively. The significant enhancement in sensing performance is due to the formation of the heterojunction between 2DPI and In 2 O 3. Besides, 2DPI acts as photocatalytic promoter in the 2DPI/In 2 O 3 composite. The 2DPI/In 2 O 3 based sensor is a promising candidate for UV-assisted NH 3 detection at room temperature. • The 2DPI/In 2 O 3 composite based sensor exhibited an enhancement of ammonia sensing properties at room temperature. • The sensing performance of the 2DPI/In 2 O 3 composite based sensor was significantly improved with the irradiation of UV light. • The enhanced sensing properties were mainly attributed to the synergistic effect between 2DPI and In 2 O 3 heteronanostructures. [ABSTRACT FROM AUTHOR]

In the present study, UV light activated gas sensor was investigated for Al/Al 2 O 3 /p-Si and Al/TiO 2 /Al 2 O 3 /p-Si samplesby atomic layer deposition method (ALD). Generally, in order to obtain the sensing performance, traditional metal oxide semiconductor gas sensors are operated at 100–400 °C. However, this temperature range limits their applications to flammable gases, and causes high power consumption. It is important to note that sensing performance experiments should have been performed at room temperature. With the support of UV light, gas sensors do not need to be heated and they can work at room temperature easily. For this purpose, electrical measurements have been performed on sensing performance with and without UV irradiation for dedection of NO 2 gas. With the help of UV irradition, we obtained good sensitivity at the room temperature for Al/TiO 2 /Al 2 O 3 /p-Sistructure but under the same conditions no result was obtained for Al/Al 2 O 3 /p-Si structure. Without UV irradiation, there was no sensitivity for both.We observed that increasing of sensitivities at the room temperature show a direct effect of the light on the adsorbed oxygen ions. According to the relation of photocatalytic reaction and photoactivated gas sensing process, we concluded that TiO 2 might be an acceptable sensor for detection of nitrogen dioxide (NO 2 ) at room temperature under UV illumination. [ABSTRACT FROM AUTHOR]

A number of porous InGaN samples of relatively high In composition ∼47% were prepared via electrochemical etching using diluted KOH bath. The porous samples were synthesised with the assistance of different types of illumination; Xenon and UV light. Fabrication of porous InGaN without light illumination was also demonstrated. The effects of using different light sources on the properties of porous InGaN were studied for the first time. Observation through field emission scanning electron spectroscopy (FESEM) revealed that different types of illumination resulted in different surface morphologies. Overall, the high resolution X-ray diffraction (HR-XRD) rocking curves measurement showed that the value of full width at half maximum (FWHM) of all etched samples decreased relative to the as-grown sample due to removal of dislocation defects on the surface after etching. It should be noted that, etched sample that used Xenon illumination showed the lowest FWHM value. On the other hand, photoluminescence (PL) measurement indicated that all of the porous InGaN samples exhibited higher PL intensity than the as-grown sample, showing improvement in the aspect of optical property. Moreover, red-shifted characteristic in PL spectra was also observed in the porous samples, suggesting a relaxation of compressive stress occurred in the samples. The properties observed imply the potential utility of porous InGaN in optical and sensor applications. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO 2 ), which is the widely used photo-catalyst, has been synthesized by simple hydrothermal solution containing tetrabutyl titanate and hydrofluoric acid. The synthesized product has been applied to photo-degradation in aqueous phase of chlorinated solvents, namely tetrachloroethene (PCE), trichloroethene (TCE) and 1,1,1-trichloroethane (TCA). The photo-degradation results revealed that the degradation of these harmful chemicals was better in UV/synthesized TiO 2 system compared to UV/commercial P25 system and UV only system. The photo-catalytic efficiency of the synthesized TiO 2 was 1.4, 1.8 and 3.0 folds higher compared to the commercial P25 for TCA, TCE and PCE degradation, respectively. Moreover, using nitrobenzene (NB) as a probe of hydroxyl radical (·OH), the degradation rate was better over UV/synthesized TiO 2 , suggesting the high concentration of ·OH generated in UV/synthesized TiO 2 system. In addition, ·OH concentration was confirmed by the strong peak displayed in EPR analysis over UV/synthesized TiO 2 system. The characterization result using XRD and TEM showed that the synthesized TiO 2 was in anatase form and consisted of well-defined sheet-shaped structures having a rectangular outline with a thickness of 4 nm, side length of 50 nm and width of 33 nm and a surface 90.3 m 2 /g. XPS analysis revealed that ≡Ti-F bond was formed on the surface of the synthesized TiO 2 . The above results on both photocatalytic activity and the surface analysis demonstrated the good applicability of the synthesized TiO 2 nano-sheets for the remediation of chlorinated solvent contaminated groundwater. [ABSTRACT FROM AUTHOR]

Abstract: Building materials are regularly affected by the growth of microalgae. The consequences are mainly aesthetic but the colonization can cause biodeterioration of the material in the most extreme cases. This study investigates two building material treatments that can potentially inhibit or slow down such growth: photocatalytic coatings and water repellent treatments. The efficiency of these treatments in terms of biological growth inhibition was tested on the algae species Graesiella emersonii. Algal growth on building materials was investigated using two accelerated tests simulating different types of humidification (water capillary ascent and water run-off) under different lighting conditions. Mortars treated with photocatalytic coating or with water repellent were studied. The algal growth on the mortar surface was evaluated using image analysis (area covered and intensity of fouling). No slow down of the biological growth kinetics could be attributed to photocatalytic substrates. However, for mortars impregnated with a water-repellent preparation, algal growth slowed significantly under water run-off and even stopped under water capillary ascent. [Copyright &y& Elsevier]

In/ZnO/p-Si heterojunction diode was produced to investigate the photo-responsivity and electrical features under ultraviolet (UV) light. A hydrothermal synthesis technique was used to coat the ZnO layer on the p-Si single crystal as nanowhisker/rods. The formation of surface and nanowhisker properties of the ZnO layer were investigated by scanning electron microscope (SEM). The I-V (current-voltage) analysis of the In/ZnO/p-Si diode was realized in dark and under UV (290–400 nm) illumination. Further, the main electrical parameters of the diode; such as reverse bias saturation current (I-V), ideality factor (n), zero bias barrier height (Ф Bo), resistance (R) and interface state density (N ss) were obtained from the experimental I-V measurements by thermionic emission (TE) and Card and Rhoderick's function. Also, the power law of the photocurrents (I PC), photo-responsivity (PR) and response time were extracted. Photo-responsivity and response time values of In/ZnO/p-Si heterojunction diode were obtained as 2.0 A/W and (rise/decay) 160/200 ms, respectively. [Display omitted] • Hydrothermal synthesis route was used to prepare the ZnO on the p-Si single crystal as nanowhisker/rods. • Photo-responsivity and response time values were obtained as 2.0 A/W and (rise/decay) 160/200 ms, respectively. • A significant increase in photo-responsivity is obtained with the device. [ABSTRACT FROM AUTHOR]

We report on inverted solar cells using amine-containing polymer (polyethylenimine ethoxylated, PEIE) modified fluorine-doped tin oxide (FTO) as the electron-collecting electrode. PEIE lowers the work function of FTO from 4.6eV to 3.8eV, measured by Kelvin probe, sufficiently low for collecting electrons in solar cells. With the FTO/PEIE electrode, inverted solar cells based on poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene)-2,6-diyl]:phenyl-C61-butyric acid methyl ester exhibited an open-circuit voltage of 0.70±0.01V, a short-circuit current density of 15.2±0.2mA/cm2, a fill factor of 0.60±0.01 and a power conversion efficiency of 6.3±0.2% averaged over 9 devices under 100mW/cm2 AM1.5 illumination, which is comparable to the solar cells fabricated on indium–tin oxide glass substrates. In addition, we found that ultraviolet light-containing illumination can reduce the work function of bare FTO from 4.66eV to 4.34eV presumably because of the desorption of oxygen trapped in FTO. [ABSTRACT FROM AUTHOR]

Highlights: [•] Novel [Bi6O6(OH)3](NO3)3·1.5H2O sheets photocatalyst was synthesized and characterized. [•] The catalyst exhibited better photocatalytic effects superior to that of classic TiO2 P25. [•] Photodegradation mechanism was direct oxidation/reduction product of phenol by HO / . [ABSTRACT FROM AUTHOR]

Abstract: The room temperature sensing of formaldehyde with macroporous TiO2 based semiconductor-type sensor in the presence of humidity and UV irradiation was investigated using impedance spectroscopy. The normalized change in impedance in the presence of the formaldehyde was used to calculate the sensor response. A linear increase in sensor response to concentrations of formaldehyde in the range from 10ppm to 50ppm was observed. Significant enhancement of the sensor response was observed in the presence of both UV illumination and low relative humidity (∼6%). It is proposed that the role of UV illumination was to generate hydroxyl groups from the adsorbed water on the titania, and these active hydroxyl groups reacted with formaldehyde to enhance the sensor response. The a.c. impedance-type signals with formaldehyde were more stable than the conventional multimeter-based d.c. resistance changes. A possible explanation for the more stable response under a.c. conditions is that the potential barrier due to the build-up of the dissociated protons from water adsorbed on the oxide surface is effectively suppressed under the a.c. condition. [Copyright &y& Elsevier]

Abstract: An earlier report describing a lack of compensation to imposed myopic and hyperopic defocus in chicks reared in UV lighting has led to the belief that the spatial resolving power of the UV cone photoreceptor network in chicks is not capable of decoding optical defocus. However this study used dim light rearing conditions, of less than 10lx. The purpose of the current study was to determine if emmetropization is possible in young chicks reared under higher luminance, UV lighting conditions. Young, 4day-old chicks were reared under diurnal near UV (390nm) illumination set to either 20 or 200lx while wearing a monocular defocusing lens (+20, +10, −10 or −20D), for 7days. Similarly treated control groups were reared under diurnal white lighting (WL) of matching illuminance. The WL and UV LED sources were set to equivalent illuminances, measured in “chick lux”, calculated from radiometer readings taken through appropriate narrow band interference filters, and a mathematical model of the spectral sensitivity of the chick visual system. High resolution A-scan ultrasonography was undertaken on days 0 (before lenses were fitted), 2, 4, and 7 to track ocular dimensions and refractive errors were measured by retinoscopy on days 0 and 7. Compensation to negative lenses was unaffected by UV illuminance levels, with near full compensation being achieved under both conditions, as well as under both WL conditions. In contrast, compensation to the positive lenses was markedly impaired in 20lx UV lighting, with increased instead of decreased axial elongation along with a myopic refractive shift being recorded with the +10D lens. Compensation under both WL conditions was again near normal for the +10D lens. However, with the +20D lens, myopic shifts in refractive error were observed under both dim UV and WL conditions. The spatial resolving power of the UV cone photoreceptor network in the chick is sufficient to detect optical defocus and guide the emmetropization response, provided illumination is sufficiently high. However, compensation to imposed myopic defocus may be compromised, when either the amount of defocus is very high or illumination low, especially when the wavelength is restricted to the UV range. [Copyright &y& Elsevier]

Abstract: Platinum nanoparticles were doped on TiO2 nanotube arrays (TNT/Ti) by micro-emulsion method. TiO2 nanotube arrays were successfully fabricated by anodizing of titanium sheets. The morphology and surface analysis of Pt/TNT/Ti catalysts were investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The electro-oxidation of lactose on Pt/TNT/Ti catalysts in alkaline medium was studied by cyclic voltammetry and chronoamperometry methods. The results showed that the oxidation peak currents on the Pt/TNT/Ti catalyst for lactose oxidation are about ten times larger than a smooth platinum electrode and confirmed the better electro-catalytic activity and stability of these new electrodes. The photo-catalytic properties of TiO2 make the Pt/TNT/Ti catalyst refreshable after a short UV treatment and the electro-oxidation current density of Pt/TNT/Ti catalysts after UV-cleaning can be re-established. Also Pt/TNT/Ti catalysts showed a remarkably enhanced performance for lactose oxidation under UV illumination compared to that without UV illumination. [Copyright &y& Elsevier]

Abstract: In this paper, we discuss the fabrication and characterization of pentacene-based phototransistors using indium tin oxide as a transparent electrical gate and PMMA as a transparent dielectric gate. The photoelectric properties with different pentacene film thicknesses were characterized under ultraviolet (365nm) illumination. We observed that for the thinner pentacene films, the threshold voltage upon UV illumination was shifted from its initial value in the dark to a positive voltage of more than 16V, whereas the shift was only of 3V for thicker films. Thus, we obtained a higher photosensitivity of 6.5×104 for thinner pentacene films, which indicates that the organic thin film transistors could find use in photodetector applications. [Copyright &y& Elsevier]

Abstract: Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol–gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351±5nm, was used as illumination sources. The AFM topography of AgNP/TiO2 nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO2 covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10–15% after 6 cycles compared to the initial use. [Copyright &y& Elsevier]

Abstract: Pt is one of the most important electrode materials employed in direct methanol fuel cell, and many efforts have been directed to improving its electrocatalytic performance. In this work, Pt–TiO2 nanocomposites are successfully prepared by a sol–gel method. As revealed by TEM, Pt nanoparticles with an average size of 2.6 nm are well uniformly dispersed on porous TiO2. XRD structural characterization indicates that Pt possesses a face centered cubic crystal structure while TiO2 is in the format of both rutile and anatase phases. The electrochemical performance of as-prepared nanocomposite electrode (Pt–TiO2/ITO) is evaluated by studying the electrocatalytic oxidation of methanol in an alkaline medium with or without UV illumination. Comparative experiments evince that the electrochemical performance of Pt–TiO2/ITO for methanol electrooxidation is markedly improved under UV illumination. Under UV illumination, moreover, the poisoning resistance of Pt–TiO2/ITO for methanol electrooxidation is significantly improved, as supported by the results of time-coursed current measurements. [ABSTRACT FROM AUTHOR]

Abstract: Many studies have been published on the use of TiO2 as a photocatalyst, which decomposes various organic compounds under UV illumination by generating various radicals. The purpose of the present study was to evaluate the photocatalytic bactericidal effects of variously treated titanium surfaces on Escherichia coli K-12. The specimens were fabricated from grade 4 commercially pure titanium, 12mm in diameter and 1mm in thickness. Five different surfaces were prepared (MA: machined surface; AO: anodized at 300V; NO: NaOH-treated; NW: NaOH- and water-treated; and HT: heat-treated). Surface analysis was performed using scanning electron microscopy, optical interferometer, and thin-film X-ray diffractometry. Photocatalytic activity of each group was confirmed by degradation of methylene blue (MB). The antibacterial activity was assessed by calculating the survival ratio in a drop of a culture of E. coli placed on the surface under UV illumination. Significant photocatalytic activity and bactericidal effects were observed on the titanium surfaces of AO and NW, regardless of the surface roughness (P <0.01). The group with anatase was the most susceptible to the photocatalytic effect, while the surface without anatase showed the least susceptibility. Based on this in vitro study, the crystallography of the oxide layer on its titanium surfaces is an important factor affecting the photocatalytic bactericidal activity. [Copyright &y& Elsevier]

Abstract: To increase the activity of immobilized catalyst by synergetic effect of adsorption and to extend the activity of Fe0, a composite membrane with Fe0, activated carbon fiber (ACF) and TiO2 was prepared, using dip-coating, impregnation and chemical reduction methods. The activity of the prepared membrane was evaluated for mineralizing 2,4-dichlorophenol (2,4DCP) in water under UV illumination. The co-presence of Fe0 and TiO2 enhanced 2,4DCP degradation. ACF addition and its adsorption effect were shown in promoting 2,4DCP mineralization and TOC removal by comparing activities of composite membranes with Fe0/TiO2/ACF or Fe0/TiO2. Effects of pH and iron loading ratio to TiO2 on degradation rate of 2,4DCP using the composite membrane were investigated and optimized. The optimal pH was 6 and the optimal loading of Fe0 was 1wt% to TiO2. The repeated test results and XRD patterns of catalysts before and after reaction proved that the Fe0/TiO2/ACF membrane was durable and stable in its photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Quantum dots (QDs) have been gaining popularity due to their potential application in cellular imaging and diagnosis, but their cytotoxicity under light illumination has not been fully investigated. In this study, green and red mercaptopropionic acid capped CdTe quantum dots (MPA-CdTe QDs) were employed to investigate their cytotoxicity in human pancreatic carcinoma cells (PANC-1) under UV illumination. MPA-CdTe QDs exhibited excellent photostability under UV illumination and could be easily ingested by cells. The cytotoxicity of MPA-CdTe QDs was significantly enhanced under UV illumination, which was determined by changes in cell morphology as well as by decreases in the metabolic activity and cell counting. Our results indicated that green and red QDs had different cellular distribution and exhibited distinct UV-enhanced cytotoxicity. UV illumination enhanced the generation of reactive oxygen species (ROS) in cells containing QDs, and NAC antioxidant could reduce their damage to cells under UV illumination. Moreover, the influences of different UV illumination conditions on the viability of cells containing QDs were examined and discussed in detail. [Copyright &y& Elsevier]

Abstract: The present work reports on enzyme attachment on and photoinduced release from TiO2 surfaces. TiO2 layers (amorphous and anatase) were modified with 3-aminopropyltriethoxysilane (APTES), followed by attachment of vitamin C and horseradish peroxidase (HRP). Using step by step XPS characterization and vis-spectroscopy we show that upon UV illumination the linker chain to the protein can be cut, releasing active HRP into the environment. The head silane group remains attached to the TiO2 surface. The kinetics of this photoinduced release is significantly faster for the anatase form of TiO2 compared with amorphous material. The results indicate that UV induced chain scission represents a very versatile tool for payload release from TiO2 surfaces. [Copyright &y& Elsevier]

Abstract: We report an improved performance of Pt–TiO2 nanostructure electrode for methanol oxidation in methanol fuel cells. The nanostructure electrode consisting of Pt nanophases and a titanium oxide matrix was fabricated by means of co-sputtering deposition method. The electrode showed a remarkably enhanced performance for methanol oxidation under UV illumination compared to that without UV illumination. Such a remarkably improved performance of the Pt–TiO2 electrode might be due to the enhanced methanol oxidation by photo-generated holes in the TiO2 under UV illumination. [Copyright &y& Elsevier]

The measurement of capillary rise was used for evaluating the photo-enhanced wetting ability of TiO2. Two glass plates, which were coated with TiO2 thin-films, were vertically oriented having a small gap and immersed in the several solutions. In the channel between two TiO2 thin-films, the capillary rise of liquids is determined by the surface tension of liquids and the physical–chemical nature of the contacting surfaces. The capillary rise of water was measured to be 28 mm for a TiO2 samples equilibrated in the dark for 2 h (immediately after the calcination), 29 mm for the surface pre-illuminated with UV light and 11 mm for aged samples (i.e. kept in a dark box for several weeks). A companion FT-IR study supported the fact that the capillary rise has a strong relation with the amount of adsorbed water on the surface of the TiO2 thin-films. While contact angles have been routinely measured for photoactive TiO2 systems, capillary rise is an alternative criterion for the wetting ability without expensive equipment. We also show that capillary rise can be expanded to photo-responsive motion of liquids in the TiO2 channel. The capillary rise of water tested between the two TiO2 thin-film surfaces increased by a factor of three under UV light exposure. [Copyright &y& Elsevier]

Standard and mesoporous sol–gel tungsten oxide thin films were prepared by a spin-coating technique from an ethanolic solution of tungsten hexachloride. A block copolymer (BASF™ Pluronic p123) was employed as a template to generate the mesoporous structure. An ultraviolet (UV) illumination method was employed to remove the polymer templates at room temperature. The electrochromic and optical properties of the mesoporous films are described and compared to standard sol–gel tungsten oxide films. Results are also presented on the samples prepared by thermal treatment. We demonstrate that the UV illumination/ozone treatment is a superior method to remove templates which enables us to more effectively investigate the effect of mesoporosity on the electrokinetics of ion insertion into tungsten oxide films. [Copyright &y& Elsevier]

In this paper, a coral-like tin diselenide/MOFs-derived flower-like tin dioxide (SnSe 2 /SnO 2) nanocomposite film sensor was fabricated by hydrothermal method for NO 2 gas detection. Many characterization methods were used to examine the structural composition and micro-morphology of SnSe 2 , SnO 2 , and SnSe 2 /SnO 2 samples. At room temperature, the SnSe 2 /SnO 2 composite film sensor had a higher response to 20 ppm NO 2 gas when the mass ratio of SnSe 2 and SnO 2 was 1:2. A series of experiments were performed to investigate the NO 2 sensing properties of this sensor. The results of gas-sensing tests indicated that the SnSe 2 /SnO 2 (1:2) nanocomposite sensor had excellent NO 2 gas sensitivity performance, better linearity and selectivity compared with pristine SnSe 2 and SnO 2 film sensors. In particular, the response value of the SnSe 2 /SnO 2 nanocomposite sensor towards 20 ppm NO 2 gas was obviously improved from 7.4 to 12.6 under UV illumination, and the response/recovery times towards 10 ppm NO 2 gas were shortened from 110 s/160 to 80 s/144 s. The possible NO 2 sensing mechanism was related to the heterostructure between n-type SnSe 2 and n-type SnO 2 nanomaterials, and at the same time, we proposed that photoelectrons excited by UV light could improve the sensing characteristics of the SnSe 2 /SnO 2 nanocomposite towards NO 2 gas. • The coral-like SnSe 2 /MOFs-derived nanoflower-like SnO 2 heteronanostructures were fabricated by hydrothermal method. • The SnSe 2 /SnO 2 nanocomposite sensor exhibited excellent NO 2 sensing performance at room temperature. • The sensing properties of the SnSe 2 /SnO 2 nanocomposite sensor were significantly improved under UV illumination. • The enhanced NO 2 sensing performance was attributed to the formation of n-n heterostructure and light-excited electrons. [ABSTRACT FROM AUTHOR]