Photo-assisted Deposition Research Articles

Strong metal-support interactions between Pt and CeO2 for efficient methanol decomposition

Methanol decomposition is one of the most favorable chemical processes to alleviate the limitation of hydrogen storge and transportation. However, the different requirements of metal active sites for the activation of CH and OH bonds as well as strong adsorption of *CO intermediates limit the qualitative improvement of H2 generation for methanol decomposition. Herein, the Pt nanoparticles supported on nanorods of CeO2 with abundant oxygen defects (Pt/NR-CeO2-PD), prepared by photo-assisted deposition method, significantly boosted the H2 generation from methanol decomposition with an extremely high turnover frequency (TOF) of 84,225 h−1 and a large turnover number (TON) of 15,020,776 (200 h) at 300 °C. Mechanism investigations suggested that such superior catalytic performance was derived from the strong metal-support interaction of Pt/NR-CeO2-PD, in which the abundant oxygen defect of NR-CeO2 and high electronic density of Pt contributed to the efficient activation of OH and CH bonds, respectively. In addition, the down-shifting of d-band center of Pt further promoted the desorption of *CO intermediates. These findings may guide the design of new catalytic systems via construction of active sites for methanol decomposition.

Solar light-driven selective photoelectrochemical CO2 reduction to CO in aqueous media using Si nanowire arrays decorated with Au and Au-based metal nanoparticles

To address recent energy and environmental issues, such as global warming and resource depletion, significant interest has been shown in carbon dioxide (CO2) fixation based on photoelectrochemical processes under solar light irradiation. The present paper describes the applicability of gold nanoparticles-decorated silicon nanowire arrays (Au/SiNW) as photoelectrodes to promote CO2 reduction. The decoration with Au nanoparticles of SiNW was performed by an electroless plating utilizing surface hydrogen-terminated silicon groups, generated during the nanowire formation process. Au/SiNW exhibits efficient photoelectrochemical performance for CO2 reduction to produce CO selectively in an aqueous medium under simulated solar light irradiation owing to its vertically aligned nanowire structure and Au nanoparticles as cocatalysts. The former provides high specific surface area and light trapping effect, and the latter induces selective interaction with CO2. Moreover, a unique two-steps method for Au decoration that consists of photo-assisted deposition of copper nanoparticles and the following electroless plating to replace Cu atoms to Au ones achieves more uniform decoration of SiNW with highly dispersed core–shell structured Cu@Au nanoparticles. The resulting photoelectrode, termed Cu@Au/SiNW, shows improved selectivity toward CO production and gives a good Faradic efficiency of 72% in an aqueous medium.

A Comparative Study of Pt Depositing Methods (Chemical Reduction vs Photo-Assisted Deposition) onto TiO2 Nanoparticle for Hydrogen Photo-Production

In this paper, we report a comparative study on the methods (chemical reduction and photo-assisted deposition) of incorporating Pt onto TiO2 nanoparticles (TNP) for H2 generation. The phase structure of photocatalysts was scrutinized utilizing TEM and XRD. The degree of dispersion of Pt on the TNP is measured by a pulse chemisorption technique, using TPDRO equipment. Results provided by TEM images, EDX spectra, elemental mapping, and AAS confirmed the successful deposition of Pt on TNP. XRD patterns confirm an anatase and rutile crystallite structure, while UV-vis spectra show the reduction of bandgap from a typical value of 3.2 eV to ca. 2.9 eV. It is found that there is a correlation between the amount of Pt deposited on TNP and Pt dispersion with the H2 generation. The chemical reduction method offered a higher degree of Pt deposition, resulting in a 2.75 times larger amount of deposited Pt as compared to that resulted from photodeposition. This feature is perceived to contribute higher H2 yield (3283 µmol) at 1 w% of Pt loading

Modified anti-mosquito and self-cleaning fabrics utilizing clove oil–CuO/TiO2 composites

We report on the synthesis of CuO/TiO2 composites via a photo-assisted deposition method. The encapsulated clove oil was synthesized using oil-in-water emulsification. The optimum mass ratio of CuO:TiO2 was combined with encapsulated clove oil and then coated on fabric. The obtained CuO/TiO2 composites were examined using scanning electron microscopy to scrutinize their morphology and ultraviolet-visible diffuse reflectance spectra to identify the composites’ absorption range and bandgap energy. The modified fabrics were then characterized using Fourier-transform infrared spectroscopy. The results indicated that CuO/TiO2 samples possess spheroidal shapes, while the absorption spectra of CuO/TiO2 samples were red-shifted to the visible region as the CuO content increased. Photocatalytic activities of TiO2 and CuO/TiO2 were examined by degrading methylene blue under ultraviolet light, which shows that CuO-doped TiO2 exhibits higher activity than TiO2. The self-cleaning functionality of the modified fabrics was examined using sludge solution, revealing that the modified fabrics with CuO/TiO2 composites and encapsulated clove oil (CLO-CuO/TiO2) exhibit cleaner surfaces than blank fabric. The optimum capacity of the fabrics as repellents was obtained in a sample with the smallest average mosquitoes landing of four.

Synthesis of Nano-Composite Ag/TiO2 for Polyethylene Microplastic Degradation Applications

The aim of this research is to synthesize Ag/TiO2 nano-composites to study their ability to degrade microplastics in water, followed by varying size of microplastic particles as pollutants in drinking water. The method used for synthesizing Ag/TiO2 is Photo Assisted Deposition (PAD). Characterizations done to determine the difference between TiO2 and Ag/TiO2 were SEM-EDX and UV-Vis DRS. Polyethylene microplastics were selected as samples in this study. The variation of microplastic size used is 100-125, 125-150, and 150-250 micrometers with initial concentrations of 100 ppm. Magnetic stirrers used at a rotational speed of 2000 rpm during the degradation process with a UV lamp irradiation. The addition of the Ag dopant has a good effect in microplastic degradation, where the percentage of degradation reaches 100% within 120 minutes of irradiation at an initial concentration of 100 ppm. An initial concentration of 100 ppm obtained the best percent degradation at particle size 125-150 micrometers, where 100% degradation achieved at 90 minutes irradiation.

Effect of Ag and Mn doping for methylene blue photodegradation performance

Currently, wastewater management is ineffective, operationally expensive, and difficult to be implemented in Indonesia. The photocatalyst is a technology that may answer this problem. Titania (TiO2) is a high-activity, inexpensive, stable, and non-toxic photocatalyst material. However, TiO2 has large band-gap energy and rapid recombination. In this research, TiO2 was doped by Ag (a noble metal) and Mn (a transition metal) to compare the performance of photocatalysts in organic pollutant degradation, using methylene blue. Ag/TiO2 catalyst was synthesized by Photo Assisted Deposition (PAD) method, while Mn/TiO2 was synthesized by impregnation method. The physicochemical properties of both catalysts were assessed by SEM-EDX and UV-Vis DRS. SEM-EDX indicated that both methods successfully doped Ag and Mn into TiO2. Besides, UV-Vis DRS confirmed the presence of metal dopants that caused the narrowing of the bandgap. Ag/TiO2 catalyst increased the degradation of methylene blue by up to 97% in 30 minutes. Meanwhile, the Mn/TiO2 catalyst inhibited the degradation of methylene blue. The increased activity by Ag dopants is due to the Localized Electromagnetic Field (LEMF) and Schottky barrier phenomena which increase charge separation. Meanwhile, decreased activity by Mn dopants is due to the shading effect and Mn electronic structure that can facilitate recombination at high loading. Ag/TiO2 catalyst also improved photodegradation performance of TiO2 when irradiated by visible light.

Microplastic Pollutant Degradation in Water Using Modified TiO2 Photocatalyst Under UV-Irradiation

Modified TiO2 photocatalyst has been widely studied on its ability to degrade pollutants in water. Nowadays, one of the water pollutants that significantly polluted water is microplastic. Photocatalyst TiO2 can create an oxidizing agent to degrade microplastic pollutants but have a very high recombination rate of electrons and holes. By modifying TiO2 with silver dopant using Photo-assisted Deposition (PAD) and Reduced Graphene oxide (RGO) using the ultrasonic radiation method, can highly increase the ability of TiO2 catalyst. The modified catalyst was characterized by SEM-EDX and UV-Vis DRS to analyze the properties change of the composite. The performance of composites in degrading microplastic (polyethylene) was tested under UV radiation for 4 hours. The Ag/TiO2/RGO catalyst has a significantly high degradation percentage with 76% compared to pure TiO2 and Ag/TiO2 with degradation percentage of 56% and 68% respectively.

The Technique of thin Zinc Oxide Films Synthesis by ALD Method

Article shows experimental results of thin ZnO films synthesis with required structure and thickness produced by different atomic layer deposition methods (normal temperature, thermal and photo-assisted deposition). The influence of the synthesis temperature and UV-irradiation on the characteristics of ZnO films was analyzed. Both amorphous and polycrystalline films were synthesized by changing the deposition parameters. Film optical properties were examined in UV, visible and IR range. The bandgap was determined using absorption spectra. Morphological parameters of the films were valued using the atomic force microscopy. Suppositions on film growth mechanisms were made, preliminary results of friction wear tests are quoted.

Cu-supported Cu2O nanoparticles: Optimized photodeposition enhances the visible light photodestruction of atrazine

The removal of herbicides from water by photocatalysis is essential for environmental remediation. Moreover, optimization of ecofriendly photocatalysts is an alternative approach. Here, we synthesized Cu2O nanoparticles utilizing a sol-gel technique, which were subsequently loaded with Cu nanoparticles to form Cu@Cu2O by simple photoassisted deposition with different Cu contents. The prepared nanostructures showed an increase in light absorption at longer wavelengths and a reduction in the bandgap from 2.08 eV in pure Cu2O to 1.95 eV in 15% Cu-loaded Cu2O. The photoluminescence and photocurrent experiments suggest the lowest recombination of photoinduced charges through optimizing the Cu content. The amended Cu@Cu2O led to the complete photodestruction of atrazine, a commonly applied triazine herbicide, after 30 min of visible light exposure with outstanding durability.

Photo-assisted deposited titanium dioxide for all-inorganic CsPbI2Br perovskite solar cells with high efficiency exceeding 13.6%

All-inorganic perovskite solar cells advancing in phase and thermal stability are regarded as promising candidates for high-performance optoelectronic application. Herein, a photo-assisted deposited titanium dioxide was designed and utilized as the electron-transporting layer. Photo-assisted deposited titanium dioxide demonstrated a low interfacial recombination rate and high carrier extraction efficiency. Consequently, CsPbI2Br-based all inorganic perovskite solar cells exhibit power conversion efficiencies of up to a value of 13.69%. This photo-assisted deposition method is a promising approach for scalable, convenient, and inexpensive fabrication in the future.

The induced effect of chemical and photo-assisted deposition of molybdenum sulfide on carbon towards the hydrogen evolution reaction

Abstract We report on a favorable synergy effect generated between molybdenum disulfide and different carbon supports. While MoSx species were generated by hydrolysis of [MoS4]2− in water, UV-light was employed to assist the MoS2 synthesis. It was found that the UV-assisted approach, combined with carbon supports properties, boosted the HER activity in acid solution. The synergy phenomenon between MoS2 and carbon supports was centered on sp3-like (C-defects) and sp2 domains of carbon of graphite powder (PG), multi-walled carbon nanotubes (CNT) or carbon Vulcan-XC-72 (C). The HER electrochemical kinetics on MoS2/CNT and MoS2/C proceeded via the Volmer-Heyrovsky mechanism. The stability and kinetic performance were attributed to the strong interaction between MoS2 and the surface nature of the carbon support.

Decarbonylation of Furfural to Furan over Titania-supported Palladium Nanoparticles Prepared by a Photo-assisted Deposition Method

Decarbonylation of Furfural to Furan over Titania-supported Palladium Nanoparticles Prepared by a Photo-assisted Deposition Method

Photocatalytic H2O2 production from O2 under visible light irradiation over phosphate ion-coated Pd nanoparticles-supported BiVO4

H2O2 production from O2 over Pd nanoparticle (NP) co-catalysts-supported BiVO4 was studied. Several deposition methods and conditions (active metal, co-catalyst loading, solution pH) were investigated for catalyst preparation, and the photo-assisted deposition (PAD) of Pd from an aqueous phosphate buffer solution (pH = 7) was found to be optimal, resulting in small and uniform phosphate ion (PO43−)-coated Pd NPs being selectively deposited on the reductive surfaces of the BiVO4. This catalyst exhibited better H2O2 production from O2 in the presence of methanol (CH3OH) as a hole scavenger under visible light irradiation than that by the catalysts prepared by the other methods and under other PAD conditions. It is surmised that PO43− partially coats smaller Pd NPs with a narrow size distribution on the reductive surfaces of the BiVO4, and that these NPs promote H2O2 generation synergistically by catalyzing the two-electron reduction of O2 while simultaneously inhibiting the four-electron reduction of O2 and the two-electron reduction of H2O2 to H2O.

Design of Advanced Functional Materials Using Nanoporous Single-Site Photocatalysts.

Nanoporous silica solids can offer opportunities for hosting photocatalytic components such as various tetra-coordinated transition metal ions to form systems referred to as "single-site photocatalysts". Under UV/visible-light irradiation, they form charge transfer excited states, which exhibit a localized charge separation and thus behave differently from those of bulk semiconductor photocatalysts exemplified by TiO2 . This account presents an overview of the design of advanced functional materials based on the unique photo-excited mechanisms of single-site photocatalysts. Firstly, the incorporation of single-site photocatalysts within transparent porous silica films will be introduced, which exhibit not only unique photocatalytic properties, but also high surface hydrophilicity with self-cleaning and antifogging applications. Secondary, photo-assisted deposition (PAD) of metal precursors on single-site photocatalysts opens up a new route to prepare nanoparticles. Thirdly, visible light sensitive photocatalysts with single and/or binary oxides moieties can be prepared so as to use solar light, the ideal energy source.

MODIFICATION OF Ti–6Al–4V ALLOYS FOR DENTAL IMPLANT AND ITS CAPACITY TO GROW HUMAN OSTEOBLAST ATCC

Modification of Ti–6Al–4V alloys with silver-loaded TiO2 nanotubes was investigated. In this study, TiO2 nanotube (TiNT) was grown on the surface of Ti–6Al–4V plates by means of anodization in an electrolyte solution containing glycerol, water and 0.5[Formula: see text]wt.% of NH4F. Silver particles were deposited on TiNT using a Photo-Assisted Deposition (PAD) method. Formation of crystalline phase of TiO2 on the surface was confirmed by means of XRD while its superficial morphology was observed using FESEM/EDS. Hydrophilicity was assessed by means of contact angle measurement. As-synthesized silver-loaded TiNT on osteoblast ATCC growth in vitro was also investigated in terms of its capacity in supporting osseointegration. The cell viability was determined by MTT (3-[4,5-dimethylthiazol-2yl]-2,5diphenyl-2H-tetrazolium bromide) assay and its differentiation activity was measured by alkaline phosphatase (ALP) assay. The results showed that desposition of silver on TiNT increased cell viability after 14 days culture while improving the hydrophilicity feature. Silver-loaded TiNT on Ti–6Al–4V alloy with Ag precursor concentration of 0.10[Formula: see text]M showed the optimum viability of osteoblast growth, with 14% improvement in comparison to its unmodified counterpart. The MTT assay showed that no cytotoxicity in vitro was observed on this material. This study provides corroborating evidences that the modification of Ti–6Al–4V alloy may enhance the cell viability and its prominence as dental implant materials.

Visible light-responsive Ag/LaTiO3 nanowire photocatalysts for efficient elimination of atrazine herbicide in water

Atrazine (ATZ) is a well-known herbicide used in agriculture in most countries and has caused many concerns because of its toxicity. In this work, we have prepared LaTiO3 nanowires that responsive to visible light irradiation through the photo-assisted deposition of Ag on its surface. The obtained photocatalysts were applied for the elimination of ATZ from water samples. The loading of LaTiO3 nanowires with Ag improved both surface texture and enhanced the light absorption in the visible range. The presence of Ag confirms the reduction of the bandgap of LaTiO3 down to 2.6 eV at 2.5 wt% loading. The Ag-loaded LaTiO3 nanowires exhibit a complete photodegradation of ATZ by the visible light after just 40 min at an optimized dose of 1.2 gL−1. The high performance of LaTiO3 photocatalyst due to the effect of adding Ag. The Ag reduces the electron-hole recombination that effectively outperforms the other unloaded LaTiO3 sample. The study sheds light on using perovskite oxide photocatalysts for the elimination of herbicides from wastewater under visible light irradiation.

Tremendously efficient Ag–ZnO–Zn(OH)2 nanosheets for nitrobenzene–aniline transformation via visible light irradiation

Preparation of ZnO (Z) and ZnO/Zn(OH)2 (Z/ZH) specimens was carried out practicing a hydrothermal method. Z/ZH specimens were furnished by distinctive mass% of silver (1.0, 3.0, and 5.0 mass%) utilizing photoassisted deposition regime and the attained decorated specimens were designated as (Ag1-Z/ZH, Ag3-Z/ZH, and Ag5-Z/ZH, respectively). Band-gap energy of Z makes it absorb in ultraviolet region whiles, Z/ZH and Ag-Z/ZH specimens possess band gaps that permit them to absorb in visible region. Modifying of Z/ZH specimens by Ag diminishes band-gap magnitude from 3.30 to 2.82 eV and, at the same time, reduces the speed by which electrons and holes may recombine. The photocatalytic actions of Z, Z/ZH, and Ag-Z/ZH were figured out beneath Vis light via nitrobenzene–aniline transformation. The complete and successful transformation could be achieved utilizing Ag3-Z/ZH photocatalyst with the charging of 1.2 g/l photocatalyst after 0.5 h from the beginning of the photocatalytic reaction. In addition, it was found that Ag3-Z/ZH photocatalyst could be reused five times conserving its stability.

Photoanode of coupling semiconductor heterojunction and catalyst for solar PEC water splitting

A novel ternary photoanode consists of semiconductor heterojunction (WO3/CdS) and co-catalyst (Co-Pi) was successfully designed and fabricated by hydrothermal, impregnation and photo-assisted deposition methods. The morphology and structure of material were characterized and the PEC properties of photoanode were systematically investigated. The results indicate that the heterojunction significantly extends the absorption range of visible-light and enhances the photocurrent density, and the onset potential shows a significant cathodic shift compared with pristine WO3 and CdS photoanodes. Moreover, the measured incident photon-to-current efficiency (IPCE) value exhibits a large enhancement as well. The mechanism of heterojunction and co-catalyst enhancing PEC performance also was discussed in detail in the work, which is attributed to effective separation of photogenerated electron and hole and timely transfer of the photogenerated holes accumulated at the electrode surface for water oxidation and has been confirmed by increase of carrier density and accelerating of carrier transfer from M − S plots, EIS and IMPS spectra.

Development of Flexible Electro Ceramics Films Prepared by Photo-Assisted Metal Organic Deposition (MOD) and its Electrical Component Application

Development of Flexible Electro Ceramics Films Prepared by Photo-Assisted Metal Organic Deposition (MOD) and its Electrical Component Application

Synthesis of MoS₂/TiO₂ Nanophotocatalyst and Its Enhanced Visible Light Driven Photocatalytic Performance.

Molybdenum disulfide (MoS₂), as a typical layered transition metal sulfide, has been widely used in photocatalysis. Here, we report layered MoS₂ nanosheet-coated TiO₂ heterostructures that were prepared using a simple photo-assisted deposition method. The as-prepared samples were investigated in detail by using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Results demonstrated that the MoS₂ nanosheets uniformly covered the outer surface of TiO₂. The visible light-sensitive photocatalytic activity was evaluated by the removal of methylene blue (MB) and 2-chlorophenol (2-CP) in aqueous solution. Thus, the MoS₂/TiO₂ heterostructures exhibited improved photocatalytic degradation activity under visible light compared with the pure TiO₂. Under visible light irradiation for 90 min, the degradation efficiencies of MB and 2-CP over the MoS₂/TiO₂ sample (sunlight irradiation time: 30 min) are as high as 93.6% and 70.6%, respectively. Furthermore, the corresponding mechanism of enhanced photocatalytic activity is proposed on the basis of the comprehensively investigated results from the radical trapping experiments, photoluminescence spectroscopy, and electron spin resonance analysis. The hole oxidation, hydroxyl radicals, and superoxide anion radicals act as the active species simultaneously in the photodegradation of the dye molecules. However, of these species, hole oxidation played the most important roles in the photocatalytic reaction.