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Gold doping induced strong enhancement of carbon quantum dots fluorescence and oxygen evolution reaction catalytic activity of amorphous cobalt hydroxide
摘要： Gold doping induced strong enhancement of carbon quantum dots fluorescence and oxygen evolution reaction catalytic activity of amorphous cobalt hydroxide. Water splitting using electrocatalysts is expected to provide an alternative green energy source to meet increasing energy demands as well as addressing environmental concerns related to fossil fuels. Herein, we report one-step synthesis of sulfur, nitrogen and Au-doped carbon quantum dots (Au-SCQDs) and strong enhancement of fluorescence intensity and oxygen evolution reaction (OER) catalytic activity of amorphous Co(OH)2 nanoparticles compared to pure Co(OH)2 as well as commercial RuO2 and Pt/C catalysts. Au doping into sulfur and nitrogen co-doped CQDs showed over seventy times enhanced fluorescence. OER studies of amorphous-Co(OH)2 incorporated Au-SCQDs produced current density of 178 mA cm?2 at the applied potential of 2.07 V whereas un-doped Co(OH)2 showed current density of 59 mA cm?2. To produce geometric current density of 10 mA cm?2, amorphous Co(OH)2-Au-SCQDs (CSA) required 388–456 mV overpotential depending on the Au ion concentration used for preparing the Au-SCQDs, which is equal to or lower than overpotential required by commercial electrocatalysts. The strongly enhanced OER activity of Co(OH)2-Au-SCQDs (CSA) was attributed to the presence of electronegative metallic conducting Au atoms along with the high catalytic surface area of amorphous Co(OH)2. The present studies demonstrate a new method of exploiting amorphous Co(OH)2NPs electrocatalysts that could provide more catalytically active sites by integrating an electronegative conducting Au atom doped SCQDs matrix.
关键词： amorphous cobalt hydroxide,fluorescence,water splitting,Gold doping,carbon quantum dots,oxygen evolution reaction,electrocatalysts
更新于2025-10-22 19:40:53
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Formation of 45° Silicon (110) Surface Using Triton X- <i>n</i> Surfactants in Potassium Hydroxide for Infrared Applications
摘要： Silicon (Si) micromirrors are an integral feature for many micro-optomechanical systems (MOEMS). Such mirrors are generally wet etched in alkaline solution at elevated temperature. For 90? beam steering applications, 45? slanted Si (110) plane is the prime choice fabricated with the incorporation of tensioactive surfactants. Here, Triton-Si and Triton-hydroxide (OH?)/H2O interaction using varying hydrophilic chain length Triton (X-45, X-100 and X-405) were investigated. The surfactant concentration was varied from 0 to 1000 ppm in potassium hydroxide (KOH). Triton molecules were shown to adsorb preferentially on (110) than on (100) surface. Longer chain length Triton hampered OH? access to Si surface resulting in slower etch rate. In contrast, contact angle measurement suggested that shorter Triton interfaced better with Si surface. Later, Si wafers etched in Triton 10 ppm – KOH were examined. The measured output for (110)X-45, (110)X-100, (110)X-405 and polished Si wafer reference (Rq < 5?) mirrors were 0.58, 0.76, 0.72 and 1.25 mW, respectively. Subsequently, Si-SiO2 thin film in [HLHL]2-substrate configuration was fabricated. Broadband micromirror for use in 3.0–5.5 μm spectrum range was experimentally realized with reflected efficiency of 73%.
关键词： wet etching,optical measurement,Silicon micromirrors,Triton X-n,surface roughness,potassium hydroxide,surfactants
更新于2025-09-23 15:23:52
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Acceleration of tungsten doping on vanadium dioxide (VO2) by alkali species
摘要： The monoclinic vanadium dioxide, VO2(M), undergoes reversible phase transition from monoclinic (semiconductor) to tetragonal (metal), which exhibits a good thermochromic property. VOSO4, as a vanadium source, is easy to handle produces VO2(M) under mild condition in the presence of alkali species. In this study, the effects of the additions of NH4HCO3, NH3·H2O, and NaOH on the VO2 crystal formation with/without tungsten doping for thermochromicity were investigated. NaOH, the strongest base of the three, provided the strongest and narrowest x-ray diffraction peak, while NH4HCO3, the weakest base, provided the opposite. Interestingly, for the tungsten doping to adjust the transition temperature, the use of NH4HCO3 was more suitable due to the possibility of a slow crystal frame formation as compared to the use of NaOH.
关键词： Sodium hydroxide,Vanadium dioxide,Ammonium hydrogen carbonate,Ammonium hydroxide,Tungsten doping
更新于2025-09-23 15:22:29
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Luminescent sensing film based on sulfosalicylic acid modified Tb(III)-doped yttrium hydroxide nanosheets
摘要： Sulfosalicylic acid (SSA) was used as an intercalation agent and an excellent antenna to synthesize layered rare-earth hydroxide (LRH) materials and directly obtain SSA-modified terbium-doped ytterbium hydroxide nanosheets by mechanical exfoliation. The crystal structure and morphologies of the LRHs and nanosheets were determined by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The particle size and zeta potential of the prepared nanosheets were also analyzed. The as-prepared nanosheets exhibited excellent luminescent properties. The positively charged nanosheets were electrophoretically deposited on a conductive glass to form a thin film. The luminescence of this thin film can be quenched by chromate (CrO4^2-) and bilirubin (BR), which shows good sensing properties. The quenching mechanism of the sensing film by CrO4^2- and BR was discussed based on the spectra and structure of the film.
关键词： chromate (CrO4^2-),thin-film sensor,nanosheets,bilirubin (BR),rare-earth hydroxide
更新于2025-09-23 15:22:29
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Gas sensing performance of GaOOH and β-Ga<sub>2</sub>O<sub>3</sub> synthesized by Hydrothermal method: A comparison
摘要： Gallium Oxy Hydrate (GaOOH) and β-Ga2O3 nanostructures in submicron scale have been synthesized at low temperature by surfactant-free hydro-thermal method. First, GaOOH has been synthesized using Gallium nitrate anhydrate, Ammonium hydroxide as precursors and double distilled water as solvent. As obtained GaOOH powders have been characterized by XRD, FE–SEM, UV–VIS, Thermo Gravimetric Analysis, I-V characteristics and BET surface analysis in order to reveal their structural, morphological, optical, thermal, electrical and surface properties. FE-SEM micrographs confirm the rod like and needle like morphologies of GaOOH and β- Ga2O3 samples, respectively. Porous nature of the samples observed through BET and BJH analyses. Synthesized GaOOH and β-Ga2O3 powders have been subjected to room temperature CO2 gas sensing in the range, 2000 ppm – 10000 ppm. GaOOH showed quick response of 80 s and fast recovery of 129 s at 8000 ppm while β-Ga2O3 showed quick response of 52 s at 8000 ppm and faster recovery of 98 s at 4000 ppm. Also, the repeatability studies were done for GaOOH and β-Ga2O3 films by exposing to different CO2 concentrations for a period of 6 consecutive days. β-Ga2O3 showed enhanced CO2 sensing response than that of GaOOH due to its better structural, electrical, morphological and surface properties.
关键词： Gallium Oxide (Ga2O3),Gallium Oxide Hydroxide (GaOOH),Hydrothermal method,Characterization,Room temperature CO2 sensing
更新于2025-09-23 15:21:21
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Efficacy of Er:YAG laser-assisted direct pulp capping in permanent teeth with cariously exposed pulp: A pilot study
摘要： Direct pulp capping is a minimally invasive method to preserve pulp integrity. We evaluated the treatment efficacy of Er:YAG laser irradiation combined with direct pulp capping for pulp exposure due to caries. A total of 21 patients with 22 teeth were enrolled in the conventional group (calcium hydroxide), and 24 patients with 25 teeth were enrolled in the laser-assisted group (Er:YAG laser irradiation at settings of 10 Hz, 50 mJ; combined with calcium hydroxide). The cumulative success rate of the conventional group and the laser-assisted group was 68.2% and 91.7% at 12 months, respectively. Results showed that the laser-assisted procedure increased the survival time (b = 0.04, OR = 0.07), while proximal-occlusal cavities in molars decreased the survival time (b = 0.03, OR = 12.5). Er:YAG lasers improve the effectiveness of conventional direct pulp capping (using Dycal) with limited side-effects and can be applied clinically.
关键词： dental pulp exposure,lasers,pilot projects,dental pulp capping,calcium hydroxide
更新于2025-09-23 15:19:57
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Facile and controllable synthesis of Zn-Al layered double hydroxide/silver hybrid by exfoliation process and its plasmonic photocatalytic activity of phenol degradation
摘要： Photocatalysts have attracted interest in the applications of green technology due to its efficiency to eliminate detrimental substances under light irradiation. Various design strategies to enhance the efficiency of photocatalytic processes under solar irradiation is actively searched. Building on the idea to provide a better synthesis method of photocatalyst, this study explores an effective and simple synthesis strategy of Layered Double Hydroxide (LDH) silver hybrid for photocatalyst phenol degradation. Unlike the common photodeposition method that incorporates noble metal nanoparticle on the LDH surface, this study discovered a pathway of intercalation of Ag nanoparticle into LDH interlayer space by exfoliation route. Notably, the synthesized ZnAl LDH/Ag contents of several phases: Zn2.5Al(OH)6.5O0.5(DS)0.5Ag0.3, Zn2.5Al(OH)7(HDS)0.5(DS)1.5, Zn2.5Al (OH)6.32O0.68(CO3)0.16Ag0.03, Zn2Al(OH)5.32O0.68 (CO3)0.16. A preliminary demonstration of the concept was given by the efficient photocatalytic degradation of phenol with a resulting conversion ratio of phenol under light (Xe lamp, > 340-nm cut-off filter) irradiation by 80 % in 210 min. These findings provide a new strategy to incorporate noble metal nanoparticles into LDH interlayer space as a great potential for photocatalyst.
关键词： Silver nanoparticle,Photocatalyst,Surface plasmon resonance,Layered double hydroxide,Exfoliation
更新于2025-09-23 15:19:57
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Continuous and Ultrafast Preparation of In(OH) <sub/>3</sub> , InOOH, and In <sub/>2</sub> O <sub/>3</sub> Series in a Microreactor for Gas Sensors
摘要： In(OH)3 and InOOH were synthesized in a high-temperature continuous flow microreactor, which was much faster than the hydrothermal synthesis in the Teflon-lined autoclave. The phase transition interval of In(OH)3 and InOOH is measured and the effect of aging temperatures on equilibrium compositions was also theoretically calculated. A transformation from nanorods to nanocubes was observed when the aging temperatures increased. In(OH)3 and InOOH were also synthesized with Sn dopant, which was proved to be beneficial for the transformation from In(OH)3 to InOOH. The sensors based on cubic and hexagonal In2O3 particles showed a fast response (4~5 s) and recovery (12~15 s) speed to acetone vapor at the optimum operating temperature of 290 oC. The sensor based on hexagonal In2O3 showed a higher response than that based on cubic In2O3. This work provided a rapid, continuous and high-temperature synthesis method of an In(OH)3, InOOH and In2O3 series.
关键词： Indium hydroxide (In(OH)3),Tin dopant,Indium oxide(In2O3),Indium oxyhydroxide (InOOH),Gas sensors
更新于2025-09-19 17:15:36
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Hybridizing NiCo2O4 and amorphous NixCoy layered double hydroxides with remarkably improved activity towards the efficient overall water splitting
摘要： Overall water splitting is an attractive technology to produce clean hydrogen and oxygen. In this study, we constructed amorphous NixCoy layered double hydroxide (LDH) hybridized with three-dimensional NiCo2O4 to fabricate core-shell nanowire array on Ni foam (NiCo2O4@NixCoy LDH/NF) as highly efficient electrocatalyst for overall water electrolysis. By tuning the Ni/Co molar ratio in NixCoy LDH, extremely low overpotentials of 193 mV for oxygen evolution reaction (OER) and 115 mV for hydrogen evolution reaction (HER) at a current density of 10 mA cm?2 can be achieved for the NiCo2O4@Ni0.796Co LDH/NF. Detailed investigations verify that the hybrid structure can increase intrinsic activity of the NiCo2O4@Ni0.796Co LDH/NF and enhance the charge-transfer rate. Moreover, a strong electronic interaction between the heterogeneous elements Ni and Co at the interface of the NiCo2O4 and NixCoy LDH might ultimately influence the catalytic performance.
关键词： bifunctional electrocatalyst,nanowire arrays,amorphous material,layered double hydroxide,water splitting
更新于2025-09-19 17:15:36
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A Highly Efficient and Durable Water Splitting System: Platinum Sub-Nanoclusters Functionalized Nickel Iron Layered Double Hydroxides as the Cathode and Hierarchical Nickel Iron Selenides as the Anode
摘要： Developing cost-efficient and effective catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a great challenge for the applications of high-efficiency water electrolyzers. In this work, we design a highly efficient and durable water splitting system in an alkaline solution, of which the platinum (Pt) sub-nanoclusters (average size: 0.59 nm) functionalized nickel iron layered double hydroxide nanosheets on carbon fiber cloth (Pt-NiFe LDH/CC) serve as the cathode and the hierarchical (Ni0.77Fe0.23)Se2 nanosheets on CC ((Ni0.77Fe0.23)Se2/CC) act as the anode. For the HER, the three-dimensional (3D) Pt-NiFe LDH/CC electrode with an ultralow Pt content (1.56 wt%) drives a current density of 10 mA cm-2 under an ultralow overpotential of 28 mV. For the OER, the edge-rich (Ni0.77Fe0.23)Se2/CC electrode displays a current density of 10 mA cm?2 under a small overpotential of 228 mV, and the Tafel slope is as low as 69 mV dec?1. More importantly, the assembled Pt-NiFe LDH/CC || (Ni0.77Fe0.23)Se2/CC water splitting electrolyzer exhibits a high current density of 30 mA cm?2 at a low cell voltage of 1.57 V, which is superior than that of electrolyzer assembled by the commercial 20 wt% Pt/C and RuO2 electrodes (30 mA cm?2 at 1.62 V). Additionally, the Pt-NiFe LDH/CC || (Ni0.77Fe0.23)Se2/CC electrolyzer displays excellent stability over 40 hours even at a high current density of 50 mA cm?2, which shows a great potential in the practical applications of full water splitting.
关键词： Hydrogen Evolution Reaction,Platinum Sub-Nanoclusters,Oxygen Evolution Reaction,NiFe Layered Double Hydroxide,Porous NiFe Selenide
更新于2025-09-19 17:15:36