研究目的
Investigating the NO2 and H2 sensing properties of urchin-like hexagonal WO3 nanostructures through experimental synthesis and first-principle calculations to understand the sensing mechanisms at an atomic level.
研究成果
The sea-urchin-like hexagonal WO3 nanostructure exhibits high response and selectivity for NO2 over H2, attributed to anisotropic growth facilitated by K2SO4. First-principle calculations reveal that NO2 adsorption involves significant charge transfer and electronic structure modifications, leading to increased resistance, while H2 adsorption has minimal effects. This combined experimental and theoretical approach provides insights for developing high-performance WO3-based gas sensors.
研究不足
The study is limited to H2 and NO2 gases; other gases were not investigated. The DFT calculations use GGA-PBE functional, which underestimates band gaps. The simulations are at 0 K, not accounting for temperature effects in sensing. The sensor performance might be optimized further for practical applications.
1：Experimental Design and Method Selection:
A facile hydrothermal method was used to synthesize sea-urchin-like hexagonal WO3 nanostructures. First-principle calculations using density functional theory (DFT) were employed to simulate gas adsorption on the h-WO3 (001) surface.
2：Sample Selection and Data Sources:
Samples were prepared using Na2WO4·2H2O and K2SO4 in deionized water, with pH adjusted by HCl. Characterization data were obtained from XRD, SEM, TEM, and gas sensing tests.
3：List of Experimental Equipment and Materials:
Equipment includes a Teflon-lined stainless steel autoclave, XRD (Rigaku D/Max-1200X), FE-SEM (Nova-400), HR-TEM (Libra-200), and a gas sensing test system (CGS-8, Elite Tech Co. Ltd.). Materials include Na2WO4·2H2O, K2SO4, HCl, DI water, ethanol, Al2O3 tube, Ni-Cr alloy wire, Pt wires, and Au electrodes.
4：Experimental Procedures and Operational Workflow:
Hydrothermal synthesis at 180°C for 24 h, followed by centrifugation, washing, drying, sensor fabrication by slurry coating and sintering, and gas sensing tests at various temperatures and concentrations. Computational procedures involved geometry relaxation and electronic structure calculations using VASP.
5：Data Analysis Methods:
Data analysis included XRD peak indexing, SEM/TEM image analysis, response calculation (S = Ra/Rg for H2, S = Rg/Ra for NO2), and DFT-based analysis of adsorption energies, charge transfer, density of states, and band structures.
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