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Synthesis of Cu2O/CuO Nanocrystals and Their Application to H2S Sensing
摘要： Semiconducting metal oxide nanocrystals are an important class of materials that have versatile applications because of their useful properties and high stability. Here, we developed a simple route to synthesize nanocrystals (NCs) of copper oxides such as Cu2O and CuO using a hot-soap method, and applied them to H2S sensing. Cu2O NCs were synthesized by simply heating a copper precursor in oleylamine in the presence of diol at 160 °C under an Ar flow. X-ray diffractometry (XRD), dynamic light scattering (DLS), and transmission electron microscopy (TEM) results indicated the formation of monodispersed Cu2O NCs having approximately 5 nm in crystallite size and 12 nm in colloidal size. The conversion of the Cu2O NCs to CuO NCs was undertaken by straightforward air oxidation at room temperature, as confirmed by XRD and UV-vis analyses. A thin film Cu2O NC sensor fabricated by spin coating showed responses to H2S in dilute concentrations (1–8 ppm) at 50–150 °C, but the stability was poor because of the formation of metallic Cu2S in a H2S atmosphere. We found that Pd loading improved the stability of the sensor response. The Pd-loaded Cu2O NC sensor exhibited reproducible responses to H2S at 200 °C. Based on the gas sensing mechanism, it is suggested that Pd loading facilitates the reaction of adsorbed oxygen with H2S and suppresses the irreversible formation of Cu2S.
关键词： CuO,H2S,gas sensor,Cu2O,nanocrystal
更新于2025-09-23 15:22:29
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One-step H2S reactive sputtering for 2D MoS2/Si heterojunction photodetector
摘要： A technique for directly growing two-dimensional (2D) materials onto conventional semiconductor substrates, enabling high-throughput and large-area capability, is required to realise competitive 2D transition metal dichalcogenide devices. A reactive sputtering method based on H2S gas molecules and sequential in-situ post-annealing treatment in the same chamber was proposed to compensate for the relatively deficient sulfur atoms in the sputtering of MoS2 and then applied to a 2D MoS2/p-Si heterojunction photodevice. X-ray photoelectron, Raman, and UV-visible spectroscopy analysis of the as-deposited Ar/H2S MoS2 film were performed, indicating that the stoichiometry and quality of the as-deposited MoS2 can be further improved compared with the Ar-only MoS2 sputtering method. For example, Ar/H2S MoS2 photodiode has lower defect densities than that of Ar MoS2. We also determined that the factors affecting photodetector performance can be optimised in the 8–12 nm deposited thickness range.
关键词： H2S gas,two-dimensional layered MoS2,reactive sputtering,heterojunction photodiode
更新于2025-09-23 15:19:57
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Ultra-Sensitive H<sub>2</sub>S Gas Sensor Based on WO<sub>3</sub> Nanocubes with Low Operating Temperature
摘要： WO3 nanostructure with nanocube morphology was synthesized through acidification of Na2WO4·2H2O, which were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the result of the present work implied that the sensor fabricated by nanocube WO3 could detect the level of 330 ppb H2S, which is much lower than the threshold limit value of 10 ppm. Compared with other results, the nanocube WO3 sensor shows higher sensitivity, excellent selectivity and faster response/recovery to H2S. Especially, the best operating temperature of this nanocube WO3 for H2S detection is 100 oC.
关键词： H2S,Gas sensor,Nanomaterials,WO3
更新于2025-09-19 17:15:36
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ZnTe-coated ZnO nanorods: Hydrogen sulfide nano-sensor purely controlled by pn junction
摘要： In this study, the double hydrothermal method is proposed as a facile approach to the synthesis of ZnTe/ZnO core–shell nanorods. The coating thickness of the p-type ZnTe is varied to adjust the junction depth in the n-type ZnO nanorods, and the conductance measurements reveal the change in the conduction path in the heterojunction structures. Structural and chemical investigations conducted using X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy confirm the hetero-nanostructure formation of ZnTe/ZnO. The role of ZnTe in H2S-gas sensing by the ZnO nanorods is discussed. The enhanced sensing performance observed with a thin ZnTe coating confirms the importance of the base resistance of the nano-transducer in achieving high response characteristics. The composite structure also demonstrates a superior sensing performance of good repeatability, stability, linearity, and gas selectivity at temperatures greater than 200 °C.
关键词： p-n junction,ZnO gas sensor,H2S gas sensor,nanosensor
更新于2025-09-19 17:13:59
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Effect of solid-H <sub/>2</sub> S gas reactions on CZTSSe thin film growth and photovoltaic properties of a 12.62% efficiency device
摘要： We fabricated CZTSSe thin films using optimized SLG-Mo/Zn/Cu/Sn (MZCT) as a stacked structure and described the phenomenon of Zn elemental volatilization using the MZCT stacked structure. We introduced H2S gas to effectively control the S/(S + Se) ratio of the film in the sulfo-selenization process and to suppress Zn volatilization. Unlike during the selenization process, a stable ZnSSe thin film was formed on the precursor surface during the sulfo-selenization process. The formation of the ZnSSe thin film inhibited Zn volatilization, which facilitated control of the thin film stoichiometry and played an important role in crystal growth. In addition, the sulfo-selenization process using H2S forms a grading of the S/(S + Se) ratio in the depth direction in the ZnSSe layer. The ZnSSe layer with this property causes the band gap grading in the CZTSSe absorption layer. Finally, through our optimized annealing process, we realized a world record CZTSSe solar cell with a certified power conversion efficiency of 12.62% and a centimetre-scale (1.1761 cm2) efficiency of 11.28%.
关键词： CZTSSe,H2S gas,photovoltaic,sulfo-selenization,Zn volatilization,thin film,band gap grading
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Mobile Based in Situ Detection of Live/Dead and Antibiotic Resistant Bacteria by Silver Nanorods Array Sensor Fabricated by Glancing Angle Deposition
摘要： The rapid in-situ detection of viability of bacteria is essential for human health and environmental care. It has become one of the biggest needs in biological and medical sciences to prevent infections and diseases, which usually occur in hospitals and field clinics. Nowadays, antibiotic resistance (ABR) has been grown as one of the world’s acutest public health problems, which requires a quick and efficient solution. Here, we demonstrate an easy, sensitive, user-friendly, portable, cost effective and time saving approach for detection of live, dead and drug resistant bacteria. Most of the organisms are found to produce H2S gas by their metabolism system. The endogenous H2S evolution was targeted to differentiate between live and dead as well as ABR bacteria. The silver nanorods (AgNRs) arrays sensors were fabricated by glancing angle deposition technique. The colorimetric and water wettability (contact angle) features of as-synthesized AgNRs were found to be highly sensitive and selective for hydrogen sulfide (H2S) gas. E.coli, P. aeruginosa, B. subtilis and S. aureus were used as the model organisms for this study. A drastic visible change in color as well as wetting properties of AgNRs array was observed. To make it easy, a user friendly and field deployable android based mobile app ‘Colorimetric Detector’ was developed. This dual mode detection is facile, inexpensive and can be easily scaled-up in the field of disease diagnosis.
关键词： mobile app,colorimetric detection,silver nanorods,antibiotic resistance,bacteria detection,H2S gas
更新于2025-09-11 14:15:04
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Enhanced H2S sensing performance of cobalt doped free-standing TiO2 nanotube array film and theoretical simulation based on density functional theory
摘要： A cobalt doped free-standing TiO2 nanotube (Co-doped TiNT) array film was firstly synthesized by a one-step anodization followed by immersion method. The characterization analysis results of TiNT with the field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS) proved that the doped cobalt ions had entered into the lattice of TiO2. Subsequently, the Co-doped TiNT gas sensors with different concentration of cobalt ions were developed for testing the gas-sensing properties for H2S. Compared with the undoped one, by 0.1 M Co-doping operation, working under the temperature of 300 °C, the Co-doped TiNT gas sensor was demonstrated the following superiorities: the response time and recovery time were 14 s and 4 s, which were shortened by 36.4% and 33.3%, respectively. Moreover, the Co-doped TiNT gas sensor with superior selectivity, stability and repeatability, reached the response value at 199.16 for 50 ppm H2S, which was improved by 7.6 times. Finally, based on the density functional theory (DFT), the calculated band gap of the Co-doped TiO2 decreased from 2.285 eV to 1.418 eV with a 38% decline. The mechanism simulation explained the obtained promotions in the gas sensing properties of the Co-doped TiNT gas sensor.
关键词： Cobalt ion doping,H2S gas sensor,Highly sensitivity,TiO2 nanotube array film,Density functional theory
更新于2025-09-10 09:29:36