Room-temperature ammonia gas sensing via Au nanoparticle-decorated TiO2 nanosheets.

A high-performance gas sensor operating at room temperature is always favourable since it simplifies the device fabrication and lowers the operating power by eliminating a heater. Herein, we fabricated the ammonia (NH3) gas sensor by using Au nanoparticle-decorated TiO2 nanosheets, which were synthesized via two distinct processes: (1) preparation of monolayer TiO2 nanosheets through flux growth and a subsequent chemical exfoliation and (2) decoration of Au nanoparticles on the TiO2 nanosheets via hydrothermal method. Based on the morphological, compositional, crystallographic, and surface characteristics of this low-dimensional nano-heterostructured material, its temperature- and concentration-dependent NH3 gas-sensing properties were investigated. A high response of ~ 2.8 was obtained at room temperature under 20 ppm NH3 gas concentration by decorating Au nanoparticles onto the surface of TiO2 nanosheets, which generated oxygen defects and induced spillover effect as well.

Plasma Nitridation Effect on ß-Ga2O3 Semiconductors.

The electrical and optoelectronic performance of semiconductor devices are mainly affected by the presence of defects or crystal imperfections in the semiconductor. Oxygen vacancies are one of the most common defects and are known to serve as electron trap sites whose energy levels are below the conduction band (CB) edge for metal oxide semiconductors, including ß-Ga2O3. In this study, the effects of plasma nitridation (PN) on polycrystalline ß-Ga2O3 thin films are discussed. In detail, the electrical and optical properties of polycrystalline ß-Ga2O3 thin films are compared at different PN treatment times. The results show that PN treatment on polycrystalline ß-Ga2O3 thin films effectively diminish the electron trap sites. This PN treatment technology could improve the device performance of both electronics and optoelectronics.

Editorial of Special Issue "Materials for Energy Applications 2.0".

Energy is a key factor in determining the growth of human society [...].

Carbon-Coated ZnS-FeS2 Heterostructure as an Anode Material for Lithium-Ion Battery Applications.

The construction of carbon-coated heterostructures of bimetallic sulfide is an effective technique to improve the electrochemical activity of anode materials in lithium-ion batteries. In this work, the carbon-coated heterostructured ZnS-FeS2 is prepared by a two-step hydrothermal method. The crystallinity and nature of carbon-coating are confirmed by the investigation of XRD and Raman spectroscopy techniques. The nanoparticle morphology of ZnS and plate-like morphology of FeS2 is established by TEM images. The chemical composition of heterostructure ZnS-FeS2@C is discovered by an XPS study. The CV results have disclosed the charge storage mechanism, which depends on the capacitive and diffusion process. The BET surface area (37.95 m2g-1) and lower Rct value (137 Ω) of ZnS-FeS2@C are beneficial to attain higher lithium-ion storage performance. It delivered a discharge capacity of 821 mAh g-1 in the 500th continuous cycle @ A g-1, with a coulombic efficiency of around 100%, which is higher than the ZnS-FeS2 heterostructure (512 mAh g-1). The proposed strategy can improve the electrochemical performance and stability of lithium-ion batteries, and can be helpful in finding highly effective anode materials for energy storage devices.

Removal of oxytetracycline from water by liquid-phase plasma process with an iron precipitated TiO2 photocatalyst.

This study developed a new water treatment method using liquid-phase plasma (LPP) process that can decompose oxytetracycline (OTC) remaining in the aquatic environment. Relatedly, the OTC causes damage to the human body and cannot be removed by traditional water treatment methods. The study also prepared Fe/TiO2 photocatalyst responding to visible light using the LPP process. In particular, the OTC decomposition efficiency of the LPP process improved by more than 10% with the use of the Fe/TiO2 photocatalyst as compared to that of the one with the use of bare TiO2 photocatalyst. Further, the optimal LPP process parameters and Fe/TiO2 photocatalyst amount in the LPP process for OTC decomposition were established in the study. Finally, the degradation pathway of the OTC in the LPP process was found based on the five intermediates of the LPP reaction that were detected by the liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analysis. In particular, the decomposition pathway was estimated to be involving the mineralization of the OTC through demethylation, deamination, dehydration, and ring cleavage.

A Flower-like In2O3 Catalyst Derived via Metal-Organic Frameworks for Photocatalytic Applications.

The most pressing concerns in environmental remediation are the design and development of catalysts with benign, low-cost, and efficient photocatalytic activity. The present study effectively generated a flower-like indium oxide (In2O3-MF) catalyst employing a convenient MOF-based solvothermal self-assembly technique. The In2O3-MF photocatalyst exhibits a flower-like structure, according to morphology and structural analysis. The enhanced photocatalytic activity of the In2O3-MF catalyst for 4-nitrophenol (4-NP) and methylene blue (MB) is likely due to its unique 3D structure, which includes a large surface area (486.95 m2 g-1), a wide spectrum response, and the prevention of electron-hole recombination compared to In2O3-MR (indium oxide-micro rod) and In2O3-MD (indium oxide-micro disc). In the presence of NaBH4 and visible light, the catalytic performances of the In2O3-MF, In2O3-MR, and In2O3-MD catalysts for the reduction of 4-NP and MB degradation were investigated. Using In2O3-MF as a catalyst, we were able to achieve a 99.32 percent reduction of 4-NP in 20 min and 99.2 percent degradation of MB in 3 min. Interestingly, the conversion rates of catalytic 4-NP and MB were still larger than 95 and 96 percent after five consecutive cycles of catalytic tests, suggesting that the In2O3-MF catalyst has outstanding catalytic performance and a high reutilization rate.

Hydrogen Production through Catalytic Water Splitting Using Liquid-Phase Plasma over Bismuth Ferrite Catalyst.

This study examined the H2 production characteristics from a decomposition reaction using liquid-phase plasma with a bismuth ferrite catalyst. The catalyst was prepared using a sol-gel reaction method. The physicochemical and optical properties of bismuth ferrite were analyzed. H2 production was carried out from a distilled water and aqueous methanol solution by direct irradiation via liquid-phase plasma. The catalyst absorbed visible-light over 610 nm. The measured bandgap of the bismuth ferrite was approximately 2.0 eV. The liquid-phase plasma emitted UV and visible-light simultaneously according to optical emission spectrometry. Bismuth ferrite induced a higher H2 production rate than the TiO2 photocatalyst because it responds to both UV and visible light generated from the liquid-phase plasma.

Fast-Response Colorimetric UVC Sensor Made of a Ga2O3 Photocatalyst with a Hole Scavenger.

A fast-response colorimetric ultraviolet-C (UVC) sensor was demonstrated using a gallium oxide (Ga2O3) photocatalyst with small amounts of triethanolamine (TEOA) in methylene blue (MB) solutions and a conventional RGB photodetector. The color of the MB solution changed upon UVC exposure, which was observed using an in situ RGB photodetector. Thereby, the UVC exposure was numerically quantified as an MB reduction rate with the R value of the photodetector, which was linearly correlated with the measured spectral absorbance using a UV-Vis spectrophotometer. Small amount of TEOA in the MB solution served as a hole scavenger, which resulted in fast MB color changes due to the enhanced charge separation. However, excessive TEOA over 5 wt.% started to block the catalytical active site on the surface of Ga2O3, prohibiting the chemical reaction between the MB molecules and catalytic sites. The proposed colorimetric UVC sensor could monitor the detrimental UVC radiation with high responsivity at a low cost.

Impact of Al doping on a hydrothermally synthesized ß-Ga2O3 nanostructure for photocatalysis applications.

Aluminum (Al)-doped beta-phase gallium oxide (ß-Ga2O3) nanostructures with different Al concentrations (0 to 3.2 at%) are synthesized using a hydrothermal method. The single phase of the ß-Ga2O3 is maintained without intermediate phases up to Al 3.2 at% doping. As the Al concentration in the ß-Ga2O3 nanostructures increases, the optical bandgap of the ß-Ga2O3 increases from 4.69 (Al 0%) to 4.8 (Al 3.2%). The physical, chemical, and optical properties of the Al-doped ß-Ga2O3 nanostructures are correlated with photocatalytic activity via the degradation of a methylene blue solution under ultraviolet light (254 nm) irradiation. The photocatalytic activity is enhanced by doping a small amount of substitutional Al atoms (0.6 at%) that presumably create shallow level traps in the band gap. These shallow traps retard the recombination process by separating photogenerated electron-hole pairs. On the other hand, once the Al concentration in the Ga2O3 exceeds 0.6 at%, the crystallographic disorder, oxygen vacancy, and grain boundary-related defects increase as the Al concentration increases. These defect-related energy levels are broadly distributed within the bandgap, which act as carrier recombination centers and thereby degrade the photocatalytic activity. The results of this work provide new opportunities for the synthesis of highly effective ß-Ga2O3-based photocatalysts that can generate hydrogen gas and remove harmful volatile organic compounds.

Improved High Rate and Temperature Stability Using an Anisotropically Aligned Pillar-Type Solid Electrolyte Interphase for Lithium-Ion Batteries.

Numerous reports have elucidated the advantages of SiOx-based anodes including their large capacities and superior cycling stabilities. However, these electrodes have not been optimized for use in electric vehicles (EVs), which demand even better performance stability at fast charging rates and high temperatures. Herein, we fabricated a novel solid electrolyte interphase (SEI) using nanodiamondseeds. The grown SEI comprised an assembly of pillars, with a height and diameter of approximately 600 and 250 nm, respectively. As a result, the Li||Ti-SiOx@C cell with a nanodiamond-containing electrolyte achieved a high capacity retention of 76.4% over 1000 cycles at 5 A g-1 and 50 °C, whereas the cell with no nanodiamond seeds showed a severe decay in the capacity and retained only 61.5% of its initial capacity. Furthermore, the NCM811||Ti-SiOx@C full cell constructed with the pillar-type SEI also showed a high capacity retention of 61.8% at 5 C (1 C = 200 mAh g-1) and 50 °C after 500 cycles, which was a significant improvement from the value (33.3%) demonstrated by its counterpart comprising the conventional SEI. The results obtained herein will enable the development of high-performance lithium-ion batteries.

Photocatalytic degradation of 1,4-dioxane using liquid phase plasma on visible light photocatalysts.

The compound 1,4-dioxane (DO) irritates the eyes, skin, and mucous membrane and is classified as a carcinogen. In this study, the decomposition of DO by photocatalytic reaction using liquid phase plasma (LPP) with photocatalyst was suggested. Plasma was directly discharged as an aqueous DO solution to enhance photocatalytic decomposition activity. To increase the decomposition efficiency of DO by plasma, bismuth ferrite (BFO) prepared by a sol-gel method was introduced as a visible-light photocatalyst. In the application of LPP and BFO photocatalyst, the decomposition of DO by photocatalytic reaction was evaluated. BFO showed UV-vis diffusion reflectance spectroscopy results of absorption of UV and visible light over 600 nm, with a bandgap of approximately 2.2 eV. BFO showed visible light photochemical reaction characteristics to decompose particulate matter (PM) in the irradiation of 6 W visible light LED lamps. It seems that the narrow bandgap of BFO led to the photocatalytic activity in the visible light. In the decomposition reaction of DO with a photocatalyst and LPP, BFO showed better decomposition efficiency than TiO2. BFO can cause photocatalytic reactions in both UV and visible light in the case of LPP irradiation, which emits strong ultraviolet and visible light.

Heterogeneous photocatalytic degradation and hydrogen evolution from ethanolamine nuclear wastewater by a liquid phase plasma process.

Ethanolamine in a wastewater which is released from nuclear power plant was decomposed using a plasma discharged into the solution directly. Ni-TiO2 supported on mesoporous materials were employed as a photocatalyst. The photocatalytic reaction using the liquid phase plasma led to a degradation of ethanolamine with hydrogen evolution, simultaneously. The ethanolamine in the wastewater was degraded over 90% on the photocatalytic decomposition reaction by irradiation of liquid phase plasma. The rate of hydrogen evolution increased significantly with Ni incorporation on TiO2 because the bandgap was reduced with Ni incorporation on TiO2. Incorporating Ni on TiO2 nanocrystallites brought out an improvement of the ethanolamine degradation with hydrogen generation. The rate of hydrogen evolution in the ethanolamine-containing aqueous solution was increased in comparison with that in pure water. Additional hydrogen evolution by the photodecomposition of ethanolamine was attributed to the increasing H2 production.

Decyl Glucoside Synthesized by Direct Glucosidation of D-Glucose Over Zeolite Catalysts and Its Estrogenicity as Non-Endocrine Disruptive Surfactant.

The estrogenicity of decyl glucoside was asserted as a non-endocrine disruptive surfactant with its preparation method using zeolite catalysts. Its estrogenicity was estimated using E-assay method. The decyl glucoside was synthesized by direct glucosidation from D-glucose with 1-decanol. The conversion and yield were improved with increasing of amount of acid sites of the zeolite catalysts. The decyl glucopyranoside is more hydrophilic than nonylphenol and has a high wettability. The decyl glucopyranosides exhibited extremely lower proliferation of estrogenic cell compared with nonylphenol.

Enhanced Electrochemical Performance of Carbon Nanotube with Nitrogen and Iron Using Liquid Phase Plasma Process for Supercapacitor Applications.

Nitrogen-doped carbon nanotubes (NCNTs) and iron oxide particles precipitated on nitrogen-doped carbon nanotubes (IONCNTs) were fabricated by a liquid phase plasma (LPP) process for applications to anode materials in supercapacitors. The nitrogen element and amorphous iron oxide nanoparticles were evenly disseminated on the pristine multiwall carbon nanotubes (MWCNTs). The electrochemical performance of the NCNTs and IONCNTs were investigated and compared with those of pristine MWCNTs. The IONCNTs exhibited superior electrochemical performance to pristine MWCNTs and NCNTs. The specific capacitance of the as-fabricated composites increased as the content of nitrogen and iron oxide particles increased. In addition, the charge transfer resistance of the composites was reduced with introducing nitrogen and iron oxide.

Synthesis and Electrochemical Reaction of Tin Oxalate-Reduced Graphene Oxide Composite Anode for Rechargeable Lithium Batteries.

Unlike for SnO2, few studies have reported on the use of SnC2O4 as an anode material for rechargeable lithium batteries. Here, we first introduce a SnC2O4-reduced graphene oxide composite produced via hydrothermal reactions followed by a layer-by-layer self-assembly process. The addition of rGO increased the electric conductivity up to ∼10-3 S cm-1. As a result, the SnC2O4-reduced graphene oxide electrode exhibited a high charge (oxidation) capacity of ∼1166 mAh g-1 at a current of 100 mA g-1 (0.1 C-rate) with a good retention delivering approximately 620 mAh g-1 at the 200th cycle. Even at a rate of 10 C (10 A g-1), the composite electrode was able to obtain a charge capacity of 467 mAh g-1. In contrast, the bare SnC2O4 had inferior electrochemical properties relative to those of the SnC2O4-reduced graphene oxide composite: ∼643 mAh g-1 at the first charge, retaining 192 mAh g-1 at the 200th cycle and 289 mAh g-1 at 10 C. This improvement in electrochemical properties is most likely due to the improvement in electric conductivity, which enables facile electron transfer via simultaneous conversion above 0.75 V and de/alloy reactions below 0.75 V: SnC2O4 + 2Li+ + 2e- → Sn + Li2C2O4 + xLi+ + xe- → LixSn on discharge (reduction) and vice versa on charge. This was confirmed by systematic studies of ex situ X-ray diffraction, transmission electron microscopy, and time-of-flight secondary-ion mass spectroscopy.

Simulation Protocol for Prediction of a Solid-Electrolyte Interphase on the Silicon-based Anodes of a Lithium-Ion Battery: ReaxFF Reactive Force Field.

We propose the ReaxFF reactive force field as a simulation protocol for predicting the evolution of solid-electrolyte interphase (SEI) components such as gases (C2H4, CO, CO2, CH4, and C2H6), and inorganic (Li2CO3, Li2O, and LiF) and organic (ROLi and ROCO2Li: R = -CH3 or -C2H5) products that are generated by the chemical reactions between the anodes and liquid electrolytes. ReaxFF was developed from ab initio results, and a molecular dynamics simulation with ReaxFF realized the prediction of SEI formation under real experimental conditions and with a reasonable computational cost. We report the effects on SEI formation of different kinds of Si anodes (pristine Si and SiOx), of the different types and compositions of various carbonate electrolytes, and of the additives. From the results, we expect that ReaxFF will be very useful for the development of novel electrolytes or additives and for further advances in Li-ion battery technology.

Fabrication of a Nondegradable Si@SiO x /n-Carbon Crystallite Composite Anode for Lithium-Ion Batteries.

A Si-based anode maintaining its high electrochemical performance with cycles was prepared for the nondegradable lithium-ion battery. Nanoscaled Si particles were mechanochemically coupled with approximately 3 nm thick oxide layer and n-carbon (nanoscaled carbon) crystallites to overcome silicon's inherent problems of poor electronic conductivity and severe volume change during lithiation and delithiation cycling. The oxide layer of SiO x was chemically formed via a controlled oxygen environment during the process; meanwhile, the n-carbon crystallites were obtained by mechanical fragmentation from ∼70 µm sized multilayered graphene powders with a low degree of agglomeration. The Si-based composite anode, processed by the above-mentioned mechanochemical coupling, maintained a superior discharge capacity of 1767 mA h/g through 100 cycles with a Coulombic efficiency exceeding 98% at a current density of 100 mA/g. According to our current study, the coupling of the Si particles with oxide layer and n-carbon crystallites was found to be a significantly efficient way to prevent the performance degradation of the Si-based anode.

Preparation and Characterization of Cobalt/Graphene Composites Using Liquid Phase Plasma System.

Liquid phase plasma (LPP) method was applied, for the first time, to the impregnation of cabalt nanoparticles onto graphene. Nanoparticles were dispersed uniformly on the surface of the two-dimensional graphene sheet. The electron miocroscopy observation showed approximately 2-7 nm sized spherical nanoparticles deposited on the surface of graphene sheets. The XPS and EDX analyses revealed that both metal Co and CoO were present in the Co/graphene composites synthesized by the LPP method.

Preparation of Low Molecular Weight Heparin by Microwave Discharge Electrodeless Lamp/TiO2 Photo-Catalytic Reaction.

An MDEL/TiO2 photo-catalyst hybrid system was applied, for the first time, for the production of low molecular weight heparin. The molecular weight of produed heparin decreased with increasing microwave intensity and treatment time. The abscission of the chemical bonds between the constituents of heparin by photo-catalytic reaction did not alter the characteristics of heparin. Formation of by-products due to side reaction was not observed. It is suggested that heparin was depolymerized by active oxygen radicals produced during the MDEL/TiO2 photo-chemical reaction.

Electrochemical properties of chemically processed SiO x as coating material in lithium-ion batteries with Si anode.

A SiO x coating material for Si anode in lithium-ion battery was processed by using SiCl4 and ethylene glycol. The produced SiO x particles after heat treatment at 725°C for 1 h were porous and irregularly shaped with amorphous structure. Pitch carbon added to SiO x was found to strongly affect solid electrolyte interphase stabilization and cyclic stability. When mixed with an optimal amount of 30 wt% pitch carbon, the SiO x showed a high charge/discharge cyclic stability of about 97% for the 2nd to the 50th cycle. The initial specific capacity of the SiO x was measured to be 1401 mAh/g. On the basis of the evaluation of the SiO x coating material, the process utilized in this study is considered an efficient method to produce SiO x with high performance in an economical way.