Zinc Oxide Semiconductor Research Articles

Hierarchical Bi2S3 nanothorn on ZnO core-branch photoelectrode: A promising heterostructure for enhanced photoelectrochemical water splitting

The zinc oxide semiconductor associated with defects and their recombination effect restricts the development of photoelectrode for hydrogen evolution. The combination of semiconductor hetero-junction and hierarchical interface of ZnO/Bi2S3 photoelectrode fabricated. In this study, heterostructure ZnO/Bi2S3 were studied as a photoanode with their impact of oxygen vacancy in ZnO nano rods. The trace of the Bi2S3 on the ZnO was studied and compared with pristine and oxygen annealed ZnO nano rods. The photon-luminescence studies reveal that shallow donor and acceptor defect in ZnO and restricted by Bi2S3 heterostructure. The less defect contemplations in the photoanodes accelerates up electron and hole migration leading to significant built-in potential and photocurrent generation. The appropriate method has been followed to architype less interfacial defect in ZnO(300)/Bi2S3 photoanode and boosted the photo-redox reactions for efficient hydrogen evolution. The photoanode exhibits substantial properties of photocurrent density 0.33 mA/cm2, charge transfer resistance of 700 Ω cm2 and higher inbuilt potential of −0.88V vs Ag/AgCl with 0.17 % applied bias photon to electron conversion efficiency and 0.11 % solar to hydrogen conversion efficiency.

Emerging ZnO Semiconductors for Photocatalytic CO2 Reduction to Methanol.

Carbon recycling is poised to emerge as a prominent trend for mitigating severe climate change and meeting the rising demand for energy. Converting carbon dioxide (CO2) into green energy and valuable feedstocks through photocatalytic CO2 reduction (PCCR) offers a promising solution to global warming and energy needs. Among all semiconductors, zinc oxide (ZnO) has garnered considerable interest due to its ecofriendly nature, biocompatibility, abundance, exceptional semiconducting and optical properties, cost-effectiveness, easy synthesis, and durability. This review thoroughly discusses recent advances in mechanistic insights, fundamental principles, experimental parameters, and modulation of ZnO catalysts for direct PCCR to C1 products (methanol). Various ZnO modification techniques are explored, including atomic size regulation, synthesis strategies, morphology manipulation, doping with cocatalysts, defect engineering, incorporation of plasmonic metals, and single atom modulation to boost its photocatalytic performance. Additionally, the review highlights the importance of photoreactor design, reactor types, geometries, operating modes, and phases. Future research endeavors should prioritize the development of cost-effective catalyst immobilization methods for solid-liquid separation and catalyst recycling, while emphasizing the use of abundant and non-toxic materials to ensure environmental sustainability and economic viability. Finally, the review outlines key challenges and proposes novel directions for further enhancing ZnO-based photocatalytic CO2 conversion processes.

Stepwise-Induced Synthesis and Excellent Corrosion Protection of Ce/Eu Codoped ZnO Solid Solution Materials.

Under purely inorganic conditions, a synthesis route was devised wherein elements were introduced stepwise via coprecipitation based on differences in compound solubility. This synthesis method can change the microscopic morphology of the material without relying on a templating agent, resulting in the formation of the multilayered lamellar Ce/Eu codoped zinc oxide solid solution (ZCEOSS) with a self-assembled nested imbrication structure. The study improves the critical matter of corrosion by focusing on the electron and energy transfer mechanisms. By introduction of the bandgap modulator cerium element and fluorescence enhancer europium element into the ZnO material, the anticorrosion material has been successfully endowed with both photocathodic protection and luminescent initiative/stress dual corrosion defense functions. Due to the energy level staircase protection mechanism synergistically generated by the 4f electron shell of rare-earth elements in concert with semiconductor zinc oxide, the energy band positions were modulated to progressively guide the direction of electron flow, thereby suppressing corrosion reactions. In particular, the ZCEOSS material synthesized by doping 1% cerium and 7% europium and adding rare-earth elements at pH 7 exhibited the best corrosion inhibition performance. After immersion in simulated seawater for 96 h, Tafel polarization test results showed that compared to epoxy resin and ZnO anticorrosion systems, the ZCEOSS anticorrosion system exhibited significantly improved corrosion inhibition efficiency with enhancements of 1028.3 and 402.9%, respectively. This study provides new insights into the development of highly efficient inorganic anticorrosion materials.

Zinc Oxide–Based Grätzel Cells Employing Anthocyanin Dye Sensitizers Emphasizing Environmental Sustainability

ABSTRACTThis research is centered on the investigation of a dye‐sensitized solar cell (DSSC) with a particular focus on the utilization of anthocyanin as a sensitizing agent, in conjunction with zinc oxide (ZnO) and lithium‐doped ZnO aggregates. A notable feature of this study is its emphasis on employing cost‐effective materials in the fabrication process, aligning with the quest for sustainable and economically viable solar cell technologies. This study explores a DSSC, specifically employing anthocyanin as a sensitizer, along with ZnO and lithium‐doped ZnO aggregates. The fabrication utilizes cost‐effective materials. The research delves into morphological studies of both ZnO and its doped counterpart. Fourier transform infrared spectra were recorded for both crude and purified dyes extracted from purple cabbage. The current density–voltage profile highlights superior power conversion efficiency in the DSSC using purified dye from purple cabbage sensitized with lithium‐doped ZnO semiconductor. Overall, these experimental findings underscore the potential of anthocyanin pigments for efficient energy conversion within the realm of renewable energy technologies. By employing low‐cost materials and thoroughly investigating the morphological and spectroscopic properties of the involved components, this research contributes to the ongoing efforts in advancing clean and sustainable solar cell technologies, thereby paving the achievement of environmental sustainability.

Large-scale sub-5-nm vertical transistors by van der Waals integration

Vertical field effect transistor (VFET), in which the semiconductor is sandwiched between source/drain electrodes and the channel length is simply determined by the semiconductor thickness, has demonstrated promising potential for short channel devices. However, despite extensive efforts over the past decade, scalable methods to fabricate ultra-short channel VFETs remain challenging. Here, we demonstrate a layer-by-layer transfer process of large-scale indium gallium zinc oxide (IGZO) semiconductor arrays and metal electrodes, and realize large-scale VFETs with ultra-short channel length and high device performance. Within this process, the oxide semiconductor could be pre-deposited on a sacrificial wafer, and then physically released and sandwiched between metals, maintaining the intrinsic properties of ultra-scaled vertical channel. Based on this lamination process, we realize 2 inch-scale VFETs with channel length down to 4 nm, on-current over 800 A/cm2, and highest on-off ratio up to 2 × 105, which is over two orders of magnitude higher compared to control samples without laminating process. Our study not only represents the optimization of VFETs performance and scalability at the same time, but also offers a method of transfer large-scale oxide arrays, providing interesting implication for ultra-thin vertical devices.

Sustainable and environmentally friendly synthesis of ZnO semiconductor nanoparticles from Bauhinia forficata leaves extract and the study of their photocatalytic and antibacterial activity

The growing need to obtain nanomaterials has resulted in a trend to avoid environmentally harmful methodologies involving chemicals that damage ecosystems and health by searching for natural reducers and stabilizers with zero polluting impact. In this research, zinc oxide nanoparticles were synthesized following an environmentally friendly synthesis methodology by using a natural extract of Bauhinia forficata that, thanks to its phytochemical composition rich in organic molecules such as polyphenols and flavonoids, allows the correct formation of nanoparticles by acting as stabilizers. The results of the characterizations show the proper formation of the nanoparticles and a direct relationship between the percentage used to obtain the nanoparticles and their properties. The results obtained from XRD show a hexagonal zincite shape and crystallite sizes in the range of 22.25–31.05 nm. The appearance of a signal at ∼400 cm−1 obtained from FTIR confirms the formation of the Zn-O- bond. Subsequently, the removal of different organic dyes from polluted water was analyzed using zinc oxide semiconductor nanoparticles as photocatalysts under ultraviolet light. The results show outstanding degradation of the dyes, being able to remove at least 98.0 %, 84.4 %, 94.64 %, 95.5 %, and 98.2 % for methylene blue, methyl orange, rhodamine-B, Congo red, and malachite green, respectively. Additionally, the antibacterial effect of the obtained materials against multiple pathogenic bacteria was studied. All the synthesized nanoparticle samples showed an antibacterial effect, even at low concentrations for all the analyzed pathogens. The results show the feasibility of using Bauhinia forficata to obtain zinc oxide nanoparticles and its multiple applications due to its improved properties.

Crystallinity-Driven Formation of Highly Arrayed ZnO Nanorods Via Low-Temperature Chemical Bath Deposition on Transparent Conductive Oxide Substrates

The wide-band gap semiconductor zinc oxide (ZnO) nanostructures have attracted much interest in extensive applications such as gas sensors, photoelectrodes in dye sensitized solar cells and catalysts, etc. Among the various synthesis methods of ZnO nanostructures, chemical bath deposition (CBD) method is a low cost and simple technique to synthesize nanostructures. However, there are still remaining issues on growth of well- arrayed ZnO nanostructures with high uniformity and high crystallinity. In this research, we conducted a comprehensive investigation into various parameters, including seed layers, seed-layer thickness, precursor concentration, and reaction time during CBD process. Three kinds of transparent conductive oxide (TCO) films, specifically AZO, GZO, and ITO films, each with a thickness of 300nm, were individually deposited on glass substrates using radio frequency magnetron sputtering and DC magnetron sputtering. These obtained TCO films served as seed layers for the fabrication of ZnO nanorods in CBD process. The solution was prepared with Zn(NO3)2•6H2O and hexathylenetetramine (HMTA) diluted into deionized water, which was heated to 95 °C during CBD process. As the results: 1) Effect of different seed layers: ZnO nanorods exhibited vertically aligned hexagonal structures with uniform morphology when grown on AZO and GZO thin films. The alignment was found to depend on the crystal growth direction of the underlying TCO seed layers. Higher crystallinity of the seed layer contributed to superior alignment, with the crystal mismatch ratio between ZnO nanorods and GZO/AZO films being significantly lower than that with ITO film. 2) The thickness effect investigation was using AZO films varied from 100nm to 300nm. It was found that the thickness influenced the morphology of ZnO nanorods, correlating with the grain sizes of the seed layer thin films. Increasing film thickness led to larger average grain sizes, contributing to the diameter increase of ZnO nanorods in the CBD process, resulting in the improvement of crystallinity of ZnO nanorods. 3) The precursor ratio between concentration ratio of Zn(NO3)2•6H2O and HMTA was set as 2:0.25, 2:0.5, 2:1 and 2:2 individually for ZnO nanorods growth on AZO film. Increasing HMTA concentration initially led to an increase in diameter and length of ZnO nanorods, followed by a decrease at higher ratio of 2:2. The highest crystallinity of ZnO nanorods was obtained at the optimized ratio at 2:1. 4) The growth reaction time was investigated on ZnO nanorods grown on AZO film with concentration ratio of Zn(NO3)2•6H2O and HMTA at 2:1 with varied reacting time from 1 to 5 hours in CBD process. It was found that the reaction time significantly influenced on the growth and crystallinity of well-aligned ZnO nanorods on the as-deposited AZO seed layer. The crystallinity of ZnO nanorods in (0001) growth orientation was improved when the reaction time was increased from 1 hour to 5 hours during the CBD growth. The highest crystallinity was obtained from the ZnO nanorods grown with 5 hours reaction time. When the growth reaction time was increased, more Zn2+ ions were generated and strongly bonded with oxygen. The formed ZnO could be stacked along the c-axis (0001) growth direction and resulted in the length increasing during the CBD process. All fabricated ZnO nanorods showed a high transmittance of over 70% in the visible region. The ZnO nanorods synthesized on AZO substrates with optimized fabrication conditions will be in high potential for optoelectronic applications.

Photocatalytic properties of ZnO semiconductor nanoparticles green synthesized employing Ipomoea stans leave extracts

One of the biggest problems in the ecosystem is wastewater contaminated with industrial dyes. These pollutants have a very stable chemical structure, which causes complicated removal. However, a possible alternative for wastewater treatment is zinc oxide semiconductor nanoparticles (ZnO NPs). The approach of this study was the implementation of a green synthesis methodology for the obtention of ZnO nanoparticles employing Ipomoea stans (TV) leaves as extracts. The properties of the ZnO nanoparticles synthesized at 1 %, 2 %, and 4 % w/v (weight/volume) concentration of the extract were obtained from the characterization using different techniques. The FTIR analysis determined the presence of the active functional groups attached to the surface, which capped and stabilized the ZnO NPs; a band located in the range of 500-390 cm−1 confirms the presence of the Zn–O bond. The UV absorption spectra of all ZnO NPs samples were determined by executing the ultraviolet–visible spectroscopy technique, with a characteristic signal located at ∼370 nm and energy gap values between 3.036 eV and 3.101 eV. In addition, XRD patterns determined the average crystallite sizes to be 30.78 nm for ZnO-TV 1 %, 18.68 nm ZnO-TV 2 %, and 11.96 nm ZnO-TV 4 %, respectively. Furthermore, the results from transmission electron microscopy (TEM) displayed the following values of mean particle size of 21 nm, 24.4 nm, and 10.16 nm for ZnO-TV 1 %, ZnO-TV 2 % and ZnO-TV 4 % with S.D. 9.10, 12.5 and 3.6. Finally, the photocatalytic activity was evaluated utilizing the industrial dyes Methyl Orange, Methylene Blue, Rhodamine B, Malachite Green, and Congo Red. Obtaining outstanding results in the degradation of all industrial dyes. All syntheses achieved degradation greater than 91 % for methyl orange, methylene blue, and rhodamine B.

Enlightenment of Deionized‐Water Bathing IGZO TFTs

AbstractAt present, amorphous indium–gallium–zinc oxide (IGZO) semiconductor has become the most commonly used semiconductor material and is widely used in flat panel displays and various sensors, but its performance is greatly affected by environmental factors, especially water. This study investigates the instability of IGZO thin‐film transistors (TFTs) soaked in deionized water. After 24 h bathing, the field‐effect mobility and threshold voltage change a little, but the subthreshold swing, positive bias stress and negative bias stress stability undergo clear degradation. Through comprehensive examination of the changes in the chemical composition, surface morphology and thickness of the IGZO films, it's found that IGZO experiences selective etching by deionized water, and consequently the film surface becomes rough and rich of In and oxygen vacancies, which can explain the variations on device performance well. In addition to the bathing experiment performed on In2O3, Ga2O3, and ZnO TFTs, a schematic image of the reaction between water and IGZO is depicted, showing the preferential loss of Ga and Zn located next to the oxygen vacancy.

Investigation of structural, optical, electrical, thermoelectric and optoelectronic properties of undoped ZnO, Sb-doped ZnO and Sb–B co-doped ZnO thin films

Pure ZnO (Zinc oxide), 1 % Sb (antimony) doped ZnO (Zn0.99Sb0.01O), and 1 % Sb–1% B (boron) co-doped ZnO (Zn0.98Sb0.01B0.01O) solutions were prepared using the sol-gel method. These solutions were deposited as thin films on glass and Si (silicon) substrates via dip coating and spraying methods. In this study, doping ZnO with low amounts of Sb and B provided the conversion of the n-type semiconductor ZnO into a p-type semiconductor. The produced thin films were pure and had wurtzite ZnO polycrystalline structure. The nanodot morphology of ZnO turned into a mixture of nanodot and nanorod structures with only Sb doping. Moreover, the band gap energy of ZnO decreased from 3.26 eV to 3.24 eV with Sb doping and to 3.23 eV with Sb and B co-doping, accompanied by a decrease in optical transmittance depending on film thickness. All samples exhibited diode characteristics. According to the created Au/ZnO–Zn0.99Sb0.01O – Zn0.98Sb0.01B0.01O/Si diodes, it was understood that the ideality factor, barrier height, and serial resistance of ZnO material decreased with doping. Especially, the ideality factor, barrier height, and serial resistance of the ZnO sample decreased from 4.95, 6.80 eV, and 1.42 × 105Ω to 4.35, 6.25 eV, and 2.60 × 103Ω, respectively, with Sb and B co-doping. The photovoltaic performance of 1 % Sb-doped thin film increased 100 times compared to pure ZnO, reaching the efficiency from 0.006 to 0.600. However, the most suitable material for use as a photodiode was found to be the 1 % Sb–1% B co-doped sample. While the leakage current of this sample is around −8.0 × 10−5 A at −3 V under 100 mW/cm2 light, it is 9.5 × 10−8 A at −3 V in the dark. Furthermore, the 1 % Sb-doped thin film exhibited the best performance as a thermoelectric material at 600 K, achieving a figure of merit (ZT) of 0.00052. Overall, co-doping with Sb and B enhanced the optical, electrical, and structural (more homogeneous and less surface roughness) properties of ZnO, while improving its optoelectronic functionality such as photodiode. On the other hand, thermoelectric and solar cell properties of ZnO were enhanced with only 1 % Sb doping. A hybrid energy system containing thermoelectric and solar cells was produced cheaply and simply for wide application areas with this study. Moreover, with such a low doping amount, p-type material production was achieved, and important physical properties of the ZnO material were improved.

Preparation of biodiesel by transesterification of castor oil catalyzed by flaky halloysite supported ZnO/SnO2 heterojunction photocatalyst

Biodiesel belongs to renewable energy and is a potential substitute for petrochemical diesel. In this study, ZnO/SnO2@halloysite heterojunction photocatalyst was prepared by loading semiconductor zinc oxide and tin dioxide on layered kaolin by the improved wet calcination method, which was used to photocatalytic the transesterification of castor oil and ethanol to produce biodiesel. TG-DTG, BET, XRD, UV–vis and SEM-EDS were used to characterize the composition, specific surface area, light absorption characteristics and photocatalytic performance of the samples. The reaction conditions were optimized by the Taguchi method. The optimum reaction conditions were as follows: catalyst dosage 4 wt%, molar ratio of ethanol to oil 12:1, reaction temperature 75 °C. After 2 h, the yield of biodiesel was 96.75 %. In the study of catalyst reusability, the yield of biodiesel is still above 85 % after being reused for 5 times. The kinetics of photocatalytic transesterification was studied, and the results accorded with quasi-first-order kinetics. The activation energy was 75.02 kJ/mol. Lastly, an eight-step reaction mechanism of photocatalytic transesterification was proposed. The prepared castor oil biodiesel can be prepared into B20 biodiesel through additives or mixing to meet ASTM D6751 and EN 14214 standards.

Three-dimensional Modeling of Core-structured Field Effect Transistor

Objective: In our previous publication, a core-structured field effect transistor (CoreFET) device shows field effect transistor (FET) behavior. In this work, we investigated factors such as the thickness of the film and the channel on the conductivity of the device in order to optimize the geometry to provide guidance on the fabrication of the device with the best performance. Methods: This study uses Silvaco ATLAS numerical simulation software to investigate the performance of CoreFET. The effects of the thickness of the dielectric layer, SiO2, and the distance between the drain and source (channel length) on the conductivity of the semi-conductor indium gallium zinc oxide (IGZO) have been studied. The flat FET models with the same parameters were used for comparison. Results: Our simulation results demonstrate a directed correlation between the optimized conductivity of the device and the thickness of the dielectric material, as well as the length of the channel. Enhanced sensitivity is achievable by employing a thinner dielectric layer and a narrower channel. Conclusion: According to the results, the device can achieve better performance by optimizing the thickness of the insulator and the gap distance between drain and source electrodes. The remarkable similarity between them indicates that the FET effect remained largely unaffected by variations in FET shape. This observation suggests a consistent outcome across FETs, reinforcing the notion that CoreFET exhibits comparable results as those of film FETs. This finding significantly broadens the scope of CoreFET applications.

Photocatalytic degradation of organic dyes in water using semiconductor ZnO nanoparticles synthesized using Crataegus mexicana extract

In this work, the synthesis of zinc oxide (ZnO) nanoparticles was made using an eco-friendly methodology with a natural extract. The fruit of tejocote (Crataegus mexicana) was used as a stabilizing agent for synthesizing zinc oxide nanoparticles (NPs). Once the NPs were obtained, diverse characterization techniques were used to determine the physicochemical and optical properties of the ZnO NPs; the ultraviolet–visible spectroscopy was used to determine the uv absorption spectra of ZnO NPs and the bandgap of the material, the FT-IR spectrum of the ZnO NPs shows the presence of the Zn–O bond at 560 cm−1, XRD results show that the ZnO NPs exhibit a hexagonal crystal structure zincite type, the SEM confirms slight agglomerations between nanoparticles, Also from TEM results, the nanoparticles present a quasi-spherical morphology with sizes ranging from 18.25 nm to 36.88 nm, indicating an influence of the concentration of the Crataegus mexicana extract in the synthesis process of ZnO NPs. Photoluminescence spectroscopy of ZnO NPs shows strong emission bands in the visible spectrum around 425 nm, 467 nm, and 492 nm, and weak emission bands in the UV spectrum were observed. Finally, a photocatalytic study was realized for the photodegradation of 5 pollutant dyes: methylene blue (MB), malachite green (MG), congo red (CR), rhodamine b (RB), and methyl orange (MO). The results show degradation of the organic dyes after 180 min by a photodegradation process where ZnO nanoparticles act as a photocatalyst, indicating that the synthesized ZnO nanoparticles have excellent photocatalytic properties.

Analysis of metal and zinc oxide semiconductor interface resistance using transmission line method

The transmission line method (TLM) is modified to analyze the contact resistance between the metal and zinc oxide semiconductor considering interface resistance. TCAD is used to simulate an ideal defect-less state and compare it with experimental result. It is found that the current transfer length can be overestimated in conventional TLM measurement. The importance of interface resistance is shown through interface trap and Schottky contact effect analysis: Resistance comparison between different metal used device, and the activation energy shift measurement after O2 pre-annealing. Based on these, the conventional resistance equation for TLM is corrected by separating channel resistance and non-ideal contact resistance. The mobility and temperature coefficient of resistance (TCR) of ZnO channel are extracted using the suggested method. This shows the importance of metal/semiconductor interface resistance in devices using semiconductor channel.

Investigation of the effect of graphene oxide nanoparticles on the structural and dielectric parameters in zinc oxide semiconductors

In this study, pure and 1%, 3% and 5% doped graphene oxide (GO) reinforced zinc oxide (ZnO) nanoparticles were synthesized by sol-gel method. The aim was to improve the electrical and dielectric properties of ZnO semiconductor metal oxide used in many electronic, optoelectronic and electrochemical technologies. FE-SEM, X-ray diffraction (XRD), Raman spectroscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy (FT-IR), were used to show the structural and morphological properties of the synthesized ZnO and GO doped ZnO nanoparticles. Impedance analysis was used to study the dielectric properties of the produced nanoparticles. XRD analysis revealed typical peaks of nGO and ZnO nanoparticles. Through the FE-SEM and XRD analysis, it was shown that the ZnO and GO nanopowders were successfully synthesized. The results revealed that ZnO-GO nanoparticles, having good dielectric constant with loss and AC conductivity values, such materials can be a good candidate for solar cells and photovoltaic devices.Graphical

Modified Ag-ZnO coated graphene oxide ternary composite for superior photocatalytic degradation of crystal violet dye under visible light irradiation

The enhancement of advanced nanomaterials into photocatalytic applications has preserved a significant curiosity for its potential to address environmental challenges. To address this concern, a green and eco-friendly catalyst was fabricated. In this study, we examined the enhancement of the photocatalytic activity of various synthesized composites with the modification of graphene oxide (GO) and Ag over the surface of semiconductor zinc oxide (ZnO). The simple wet chemical method was used for the synthesis of ZnO, GO(x)@ZnO, Ag2@ZnO and GO(x)Ag2-ZnO composites [x = 1,3,5 wt%]. The synthesized samples were characterized by different techniques such as XRD, SEM-EDS, DRS, Raman, and PL. Ternary GO5@Ag2-ZnO photocatalyst exhibited superior degradation efficiency up to 97 % in degrading crystal violet (CV) dye, a persistent and environmentally concerning pollutant under visible light irradiation. The significant photocatalytic activity was attributed to the surface plasmon resonance (SPR) phenomenon of Ag, whose broad absorption band was observed in DRS, better electron mobility, and a large surface area of GO facilitates the charge transfer. The highly efficient catalyst was effectively employed for five repeating cycles with only an 11 % decrease in removal rate, demonstrating that it can be easily reused. Kinetic study reveals that the prepared composite follows a pseudo-first-order reaction model with the highest rate constant value of 0.02491 min−1 respectively. The possible degradation pathway was determined using the HRMS technique.

Role of Structural Decisive via Ultra‐Sonication on Photocatalytic Response of MWCNTs Intercalated ZnO Composites

AbstractIn this manuscript role of MWCNTs on the photocatalytic response of zinc oxide (ZnO) semiconductor photocatalyst is reported. Developing a cheap, stable, and effective photo catalyst is necessary for remediation of persistent organic pollutants. To address this challenge, ZnO/MWCNT composites are fabricated via sonication technique with interfacial engineering for effective photocatalytic response. X‐ray diffraction spectra confirms hexagonal structure of ZnO/MWCNT composites with the average particle size distribution of 73–80 nm. FT‐IR spectra confirms bonding structure, however SEM images confirm the homogeneous distribution of MWCNTs in the ZnO system which acts as an effective adsorbent sites. The highest degradation (90%) of methylene blue (MB) dye on ZnO95MWCNT5 composite has been observed. It is expected that MWCNTs taking part to electron transfer facilitation in spatial separation and electron–hole pairs of ZnO during photo catalysis mechanism.

Intense pulsed light annealing of solution-based indium–gallium–zinc–oxide semiconductors with printed Ag source and drain electrodes for bottom gate thin film transistors

In this study, an intense pulsed light (IPL) annealing process for a printed multi-layered indium–gallium–zinc–oxide (IGZO) and silver (Ag) electrode structure was developed for a high performance all-printed inorganic thin film transistor (TFT). Through a solution process using IGZO precursor and Ag ink, the bottom gate structure TFT was fabricated. The spin coating method was used to form the IGZO semiconductor layer on a heavily-doped silicon wafer covered with thermally grown silicon dioxide. The annealing process of the IGZO layer utilized an optimized IPL irradiation process. The Ag inks were printed on the IGZO layer by screen printing to form the source and drain (S/D) pattern. This S/D pattern was dried by near infrared radiation (NIR) and the dried S/D pattern was sintered with intense pulsed light by varying the irradiation energy. The performances of the all-printed TFT such as the field effect mobility and on–off ratio electrical transfer properties were measured by a parameter analyzer. The interfacial analysis including the contact resistance and cross-sectional microstructure analysis is essential because diffusion phenomenon can occur during the annealing and sintering process. Consequently, this TFT device showed noteworthy performance (field effect mobility: 7.96 cm2/V s, on/off ratio: 107). This is similar performance compared to a conventional TFT, which is expected to open a new path in the printed metal oxide-based TFT field.

Enhanced photocatalytic performance of ZnO under visible light by co-doping of Ta and C using hydrothermal method.

This study attempted to improve the photocatalytic activity of zinc oxide (ZnO) semiconductors in the visible light region by introducing the co-doping of carbon (C) and tantalum (Ta) to ZnO (ZTC) using a simple hydrothermal method with the respective precursors. The obtained uniform ZTC nanoparticles with an average crystal size of 29.30 nm (according to Scherrer's equation) revealed a redshift with a decrease in bandgap (Eg) from 3.04 eV to 2.88 eV, allowing the obtained photocatalyst to absorb the energy of the visible light for photocatalysis. Furthermore, the Zn 2p and Ta 4f core level spectra confirmed the presence of Zn2+ and Ta5+ in the ZTC sample. In addition, the infrared spectra identified hydrogen-related defects (HRDs), while the O 1s spectra indicated the existence of oxygen vacancies (VO). Electrochemical tests revealed improvement in the electron conductivity and charge separation of the obtained materials. To follow, the photocatalytic performance assessment was conducted by varying the C/Zn2+ ratios (5, 10, and 15 mol%) in ZTC samples, the initial RhB concentration (7, 15, and 30 ppm), and the pH of the RhB solution (3.0-10.0). The photodegradation on ZTC samples showed the most effectiveness for a 7 ppm RhB solution with a C/Zn2+ ratio of 10 mol% in the slightly alkaline medium (pH 9.0). Additionally, ZTC also exhibited commendable durability after being reused several times. The nature of RhB photodegradation was proposed and discussed via a mechanism at the end of this work.

Solar photocatalysts: non-metal (C, N, and S)-doped ZnO synthesized through an industrially sustainable in situ approach for environmental remediation applications.

One of the biggest issues the world is currently experiencing is the scarcity of pure water due to the contamination of pure water by human activities. Highly efficient, semiconducting photocatalytic materials have great potential as future catalytic materials for facilitating the clean-up process of contaminated water. Among the many semiconductor photocatalysts, non-metal-doped zinc oxide (ZnO) nanoparticles have attracted special attention in the scientific field for environmental remediation applications. The present paper reports an easy and viable synthesis of C-, N-, and S-based ZnO semiconductor photocatalysts through a simple heating method. The structural changes in the obtained samples were studied using XRD, TG/DTA, and FT-IR analyses, and morphological examinations were performed using TEM and SEM. The quantification of non-metal dopants was carried out using CNS and XPS analyses. The surface areas of the samples were analyzed using the BET method and the band energies of the samples were measured using UV-vis-diffuse reflectance Kubelka-Munk plots. Photoactivity studies were performed and revealed that the utilized in situ method resulted in the development of high-performance sulphur - (81.4%, k = 1.951 × 10-2 min-1), nitrogen - (78.5%, k = 2.271 × 10-2 min-1), and carbon - (67.2%, k = 1.392 × 10-2 min-1) doped ZnO photocatalysts. As revealed through XPS and UV analyses, a possible electron-transfer mechanism is suggested, wherein electronic transition occurred from different sub-bands when non-metal elements were introduced into the ZnO lattice. The study paves the way for the bulk-scale fabrication of doped nanoparticles through a simple heating method, whereby the unique combination of the present method with bandgap engineering will ultimately produce advanced non-metal-based ZnO photocatalysts that could find useful applications in sustainable industrial sectors.