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Bio-template assisted hierarchical ZnO superstructures coupled with graphene quantum dots for enhanced water oxidation kinetics
摘要： Due to anisotropic growth behavior and tunable electrical properties, ZnO nanostructures having dimensions such as 0-D, 1-D, 2-D and 3-D are actively studied for their optoelectronic properties. However, ZnO based photoanodes suffer from unfavorable recombination of electron hole pair, which hinders its use in photoelectrochemical (PEC) water oxidation. Herein, we demonstrate a strategy to enhance the PEC performance using bio-template assisted in-situ grown hierarchical ZnO superstructures directly over fluorine-doped tin oxide (FTO) modified by graphene quantum dots (GQDs). GQDs decorated hierarchical ZnO superstructures displayed a significant increment of ~77% in photocurrent density value compared to pristine ZnO with an impressive carrier density of 3.19 × 1020 cm?3, which is ~1.8 orders of magnitude higher than that of pristine ZnO. It is observed that GQDs acts as an efficient hole extractor, which improves the carrier separation on ZnO surface and reduces the hole trapping probability.
关键词： Hole extracting agent,Polygalacturonic acid,Hierarchical ZnO superstructures,Photoelectrochemical water oxidation,Graphene quantum dots
更新于2025-09-23 15:19:57
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Tunable Photodetectors via In Situ Thermal Conversion of TiS3 to TiO2
摘要： In two-dimensional materials research, oxidation is usually considered as a common source for the degradation of electronic and optoelectronic devices or even device failure. However, in some cases a controlled oxidation can open the possibility to widely tune the band structure of 2D materials. In particular, we demonstrate the controlled oxidation of titanium trisulfide (TiS3), a layered semiconductor that has attracted much attention recently thanks to its quasi-1D electronic and optoelectronic properties and its direct bandgap of 1.1 eV. Heating TiS3 in air above 300 °C gradually converts it into TiO2, a semiconductor with a wide bandgap of 3.2 eV with applications in photoelectrochemistry and catalysis. In this work, we investigate the controlled thermal oxidation of individual TiS3 nanoribbons and its influence on the optoelectronic properties of TiS3-based photodetectors. We observe a step-wise change in the cut-off wavelength from its pristine value ~1000 nm to 450 nm after subjecting the TiS3 devices to subsequent thermal treatment cycles. Ab-initio and many-body calculations confirm an increase in the bandgap of titanium oxysulfide (TiO2-xSx) when increasing the amount of oxygen and reducing the amount of sulfur.
关键词： TiS3,2D materials,photodetectors,DFT GW,oxidation,TiO2,Raman spectroscopy
更新于2025-09-23 15:19:57
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Graphene oxide/multia??walled carbon nanotubea??Therminol??66 hybrid nanofluids for lowa??toa??medium temperature volumetric solar collectors
摘要： Nano-composites of graphene oxide (GO) and multi-walled carbon nanotube (MWCNT) were prepared by a simple physical method and well dispersed into Therminol? 66 to form hybrid nanofluids with mass fractions in the range of 10 to 150 ppm. The suspension stability, optical absorption properties and photo-thermal conversion characteristics of GO/MWCNT nanofluids were tested and evaluated. GO nanosheets can avoid the self-entanglement and agglomeration of MWCNTs and ensure long-time suspension stability. The solar energy absorption capability increased with the composite concentration, and the majority of incoming radiation could be absorbed in a fluid layer of 1.5 cm. There existed an optimum concentration of 100 ppm related to the indoor experiment, and the temperature could be increased up to 94°C with the corresponding efficiency improved from 52% (Therminol? 66) to 70% (100 ppm). Besides, a line focusing Fresnel lens was utilized for the outdoor solar concentrating experiment, and the photo-thermal conversion performance of hybrid nanofluids increased with the composite mass fraction from 30 to 100 ppm. A highest temperature of 153°C was achieved at 100 ppm concentration. The thermal oxidation without degradation of Therminol? 66 occurred after indoor/outdoor experiments, and slightly enhanced the optical absorption owing to the solar radiation induced heating effect. The GO-MWCNT/Therminol? 66 nanofluids exhibit a good prospect in volumetric solar thermal systems from low to medium temperatures.
关键词： photo-thermal conversion performance,solar thermal energy,volumetric solar thermal collector,nanofluid,thermal oxidation
更新于2025-09-23 15:19:57
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Highly efficient photoelectrochemical water oxidation enabled by enhanced interfacial interaction in 2D/1D In2S3@Bi2S3 heterostructures
摘要： Van der Waals (vdW) heterostructures have received tremendous attention in low dimensional semiconductors due to interfacial surface reconstruction and electronic coupling effects. Here, we report mixed-dimensional 2D/1D In2S3@Bi2S3 heterostructures synthesized via two-step solvothermal in-situ growth. Theoretical calculations demonstrate In2S3 nanosheets and Bi2S3 nanorods are integrated together through the vdW interaction. Through theoretical calculations and experiment, the results confirm the surface potential of Bi2S3 is higher than In2S3, implying the free electrons will flow from Bi2S3 to In2S3 when the two semiconductors contact, leading to electron’s and hole’s accumulation at In2S3 and Bi2S3 surface. This redistribution of charges will induce an outward vector of built-in electric field at the In2S3@Bi2S3 interface (from Bi2S3 to In2S3), thereby improving hole’s transfer to In2S3 and electron’s transfer to Bi2S3. The advanced heterostructure aids in shortening the photogenerated electrons’ transport time (14 μs), promoting the electron-hole’s separation, and presents 13.3-fold enhancement in photocurrent density when compared to In2S3.
关键词： water oxidation,photoelectrochemical,interface interaction,In2S3@Bi2S3,heterostructure
更新于2025-09-23 15:19:57
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Light-Controlled Nanoparticle Collision Experiments
摘要： Electrochemical monitoring of catalytically amplified collisions of individual metal nanoparticles (NP) with ultramicroelectrodes (UME) has been extensively used to study electrocatalysis, mass-transport, and charge-transfer processes at the single NP level. More recently, photoelectrochemical collision experiments were carried out with semiconductive NPs. Here we introduce two new types of light-controlled nano-impact experiments. The first experiment involves localized photodeposition of catalyst (Pt) on TiO2 NPs with a glass-sheathed carbon fiber simultaneously serving as the light guide and collector UME. The collisions of in situ prepared Pt@TiO2 NPs with the carbon surface produced blips of water oxidation current, while the activity of pristine TiO2 NPs was too low to yield measurable signal. In another experiment, collisions of catalytic (Ir oxide) NPs with the semiconductor (Nb doped n-type TiO2 rutile single crystal) electrode are monitored by measuring the photocurrent of water oxidation.
关键词： electrochemical monitoring,catalysis,photoelectrochemical collision,nanoparticles,water oxidation
更新于2025-09-23 15:19:57
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Highly Reproducible and Efficient FASnI <sub/>3</sub> Perovskite Solar Cells Fabricated with Volatilizable Reducing Solvent
摘要： Lead-free tin halide perovskite solar cells (PSCs) have attracted great attention because of their low toxicity, ideal band gap, and high carrier mobilities. However, the efficiency and reproducibility of tin halide PSCs has been limited because of the facile oxidation of Sn2+ to Sn4+. Herein, liquid formic acid (LFA) was introduced as a reducing solvent in the FASnI3 (FA: formamidinium) perovskite precursor solution. Unlike solid reducing additives, the LFA solvent is volatile, so no residual LFA remained in the FASnI3 perovskite film. Use of the LFA solvent resulted in production of the FASnI3 perovskite film with high crystallinity, low Sn4+ content, reduced background doping, and low electronic trap density. As a result, an efficiency of over 10% was obtained for lead-free tin halide PSCs with improved reproducibility.
关键词： tin,Lead-free,oxidation,trap density,standard reduction potential
更新于2025-09-23 15:19:57
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Impact of Tryptophan Oxidation in Complementarity-Determining Regions of Two Monoclonal Antibodies on Structure-Function Characterized by Hydrogen-Deuterium Exchange Mass Spectrometry and Surface Plasmon Resonance
摘要： Purpose Tryptophan’s (Trp) unique hydrophobic and structural properties make it an important antigen binding motif when positioned in complementarity-determining regions (CDRs) of monoclonal antibodies (mAbs). Oxidation of Trp residues within the CDR can deleteriously impact antigen binding, particularly if the CDR conformation is altered. The goal of this study was to evaluate the conformational and functional impact of Trp oxidation for two mAb subtypes, which is essential in determining the structure-function relationship and establishing appropriate analytical control strategies during protein therapeutics development. Methods Selective Trp oxidation was induced by 2,2′-Azobis(2-amidinopropane) dihydrochloride (AAPH) treatment in the presence of free methionine (Met). The native and chemically oxidized mAbs were characterized by hydrogen-deuterium exchange mass spectrometry (HDX-MS) for conformational changes and surface plasmon resonance (SPR) for antigen-antibody binding. Results Treatment of mAbs with AAPH selectively oxidized solvent accessible Trp residues. Oxidation of Trp within or in proximity of CDRs increased conformational flexibility in variable domains and disrupted antigen binding. Conclusions Trp oxidation in CDRs can adversely impact mAbs’ conformation and antigen binding. Trp oxidation should be carefully evaluated as part of critical quality attribute assessments. Oxidation susceptible Trp should be closely monitored during process development for mAbs to establish appropriate analytical control for manufacturing of drug substance and drug product.
关键词： Tryptophan oxidation,surface plasmon resonance,complementarity-determining region,hydrogen-deuterium exchange mass spectrometry,monoclonal antibody
更新于2025-09-23 15:19:57
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Ti-MOF derived TixFe1-xOy Shells Boost Fe2O3 Nanorod Cores for Enhanced Photoelectrochemical Water Oxidation
摘要： TixFe1-xOy shells, in-situ formed from thermal treatment of a Ti-containing metal organic framework, NH2-MIL-125(Ti), significantly boost the photoelectrochemical water oxidation efficiency of Fe2O3 nanorod cores. The NH2-MIL-125(Ti) was coated on the surface of the Fe2O3 nanorods with a solvothermal process, followed by a two step calcination to afford the TixFe1-xOy shell/Fe2O3 core nanorod arrays. The TixFe1-xOy shell/Fe2O3 core nanorod array electrode exhibited much improved photoelectrochemical activities over the pristine Fe2O3 nanorod array electrode, boosting photo-current densities to 26.7 folds of that achieved by the pristine Fe2O3 nanorod array electrode at 1.23 V (vs. RHE) under illumination of simulated sun light of AM 1.5G. The success may be attributed to the much enhanced charge separation enabled by the hole trapping heterojunction of TixFe1-xOy shell/Fe2O3 core. The photoelectrochemical stability of the TixFe1-xOy shell/Fe2O3 core nanorod array electrode was excellent, retaining 98.9% of the initial photo-current density after a 5 hr continuous operation. This work is the first demonstration of MOF derived core-shell heterojunction for large improvements of PEC water splitting efficiencies, and can be readily extended to a wide range of catalyst design.
关键词： NH2-MIL-125(Ti),Fe2O3 nanorod,TixFe1-xOy shell/Fe2O3 core nanorod arrays,photoelectrochemical water oxidation,photoanode
更新于2025-09-23 15:19:57
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Anion intercalated layered-double-hydroxide structure for efficient photocatalytic NO remove
摘要： Due to the easily controllable interlayer anions, metal cation composition proportion and thickness, which is beneficial to modify surface chemical state and tune bandgap, layered double hydroxides (LDHs) have great promising potential for photocatalytic applications. In this study, we have successfully synthesized the ZnAl–LDH intercalated the single anion between ZnAl cationic interlayer without anionic impurities by using a facile calcining and reconstructing routes. The electron structure and surface chemical state of the prepared products have been investigated by combining the DFT calculation and experimental characterization methods. UV–vis DRS was used to certify the light absorption of the prepared products, and we performed the DFT calculation to demonstrate the density of state and activation of reactant. These results suggested that the ZnAl–LDH–CO3 possessed the more proper band structure and superior ability to activate NO and O2 for accelerating the photocatalytic NO oxidation activity. Moreover, the In situ DRIFTS with dynamically monitoring intermediates and products over the ZnAl–LDH–CO3 was adopted to declare the photocatalytic NO oxidized process during the photocatalytic reaction process. This work illustrated the influence of different interlayer anions to the electron structure and surface chemical state of ZnAl–LDH structure through the experimental verification combined DFT calculation and the photocatalytic NO oxidized process via In situ DRIFTS analyzing, which would provide a novel way to design and fabricate the efficient photocatalysis, and understand the reaction process.
关键词： In situ DRIFTS,ZnAl–LDH,DFT calculation,Reaction process and mechanism,Photocatalytic NO oxidation
更新于2025-09-23 15:19:57
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Preparation of CO Gas Sensor from ZnO Material Synthesized via Thermo-Oxidation Process
摘要： Carbon monoxide (CO) is poisonous to human because of its nature which is capable to bind to the haemoglobin in blood stronger than oxygen, so that causing toxication and even death. Therefore a sensor to early detect the presence of CO gas is necessary. ZnO is one of semiconductor materials which widely applied as a sensor material. However, ZnO is rarely reported as a CO gas sensor material. In this study, ZnO as a sensor material has been synthesized by thermo-oxidation of Zn powder at oxidation temperature variations of 800, 850 and 900 oC. The synthesized ZnO was crushed and compacted to form pellet for sensor chip. The ZnO pellets were then sintered at 500 oC. The material structures were examined using Scanning Electron Microscope (SEM), X-Ray Diffractometer (XRD), and Brunauer-Emmet-Teller (BET) analysis. The sensitivity test towards CO gas was conducted with the variations in sensing operating temperatures of 30, 50, 100 oC and variation of CO gas input concentration of 10 ppm, 50 ppm, 100 ppm, 250 ppm, and 500 ppm. The sensitivity test results showed that the sensitivity towards CO gas decreased as the oxidation temperature increased. In addition the sensitivity increased along with the increasing of the sensing operating temperature and CO gas input concentration. Hence, the highest sensitivity value was obtained from ZnO material synthesized at 800 oC due to the highest active surface area of 69.4 m2g-1 with CO concentration of 500 ppm and sensor operating temperature of 100 oC.
关键词： thermo-oxidation,ZnO,sensitivity,CO gas
更新于2025-09-23 15:19:57