The pursuit of high performance is the eternal theme
in gas sensor
research. Because of the complexity of the response and recovery processes,
the selective detection, high response, rapid response, and recovery
remain challenging in the atmospheric environment. In this paper,
WO3 hierarchical spheres (WO3 HS) with different
crystalline phase ratios are successfully synthesized to evaluate
the relationship between the phase structure and gas-sensitive properties.
The as-prepared WO3-2 HS samples achieve superior gas sensing
characteristics including high response (S = 24.2)
and fast response and recovery speed (1 and 19 s) to 100 ppm acetone
at 300 °C. The superior acetone sensing performance probably
originates from the regulation of the phase ratios of nanosheet-based
WO3. With the decrease of orthorhombic phase and the increase
of monoclinic phase, the specificity detection to acetone is increased
significantly. The reasons for such a huge selectivity change are
discussed in detail. From the perspective of reaction kinetics, we
also compare the contributions of specific surface area and crystalline
phase impacting the gas sensing performance.
The accurate and rapid monitoring of xylene gas is highly desired for human health and environmental protection. Herein, the bowknot-like CuO architectures have been synthesized through a facile room temperature...
Electromagnetic (EM) wave absorption performance is greatly affected by the microscopic morphology of the absorbing material particles. In this study, a facile and efficient ball-milling method was applied to increase the aspect ratio of particles and prepare flaky carbonyl iron powders (F-CIPs), one of the most readily commercially available absorbing materials. The effect of ball-milling time and rotation speed on the absorption behaviors of the F-CIPs was investigated. The microstructures and compositions of the F-CIPs were determined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The EM parameters were measured using a vector network analyzer (VNA) in the frequency range of 2–18 GHz. The results indicated that the ball-milled flaky CIPs exhibited a better absorption ability than the raw spherical CIPs. Among all the samples, the sample milled at 200 r/min for 12 h and the sample milled at 300 r/min for 8 h showed remarkable EM parameters. The ball-milling sample with 50 wt.% F-CIPs had a minimum reflection loss peak of −14.04 dB at a thickness of 2 mm and a maximum bandwidth (RL < −7 dB) of 8.43 GHz at a thickness of 2.5 mm, a result that conformed with the transmission line theory. Hence, the ball-milled flaky CIPs were considered to be beneficial for microwave absorption.
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