CdFe2O4 films for electroresistive detection of ethanol and formaldehyde vapors

Spinel CdFe₂O₄ thin films were synthesized by spray pyrolysis. The structural probe studies confirmed the multicrystalline nature of the films with their spinel structure. The crystallites have sizes between 13 and 37 nm and island morphology. The energy dispersive spectroscopy reveals the presence of iron, oxygen and cadmium in the film. The room temperature electrical resistance of the thin film, best measured at a voltage of 10 V, decreases rapidly if it is exposed to vapors of formaldehyde or ethanol. The sensor has detection limits of 15 ppm for ethanol and of 15 ppm for formaldehyde and a sensitivity of 0.0387 nA per ppm of ethanol. Graphical abstract The perception on the interaction properties of alcohol vapors namely ethanol and formaldehyde in CdFe₂O₄ thin film. This work clearly suggested that the CdFe₂O₄ material is a good candidate for sensing ethanol and formaldehyde vapor molecules.

High-Performance Photoelectronic Sensor Using Mesostructured ZnO Nanowires

Semiconductor photoelectrodes that simultaneously possess rapid charge transport and high surface area are highly desirable for efficient charge generation and collection in photoelectrochemical devices. Herein, we report mesostructured ZnO nanowires (NWs) that not only demonstrate a surface area as high as 50.7 m²/g, comparable to that of conventional nanoparticles (NPs), but also exhibit a 100 times faster electron transport rate than that in NP films. Moreover, using the comparison between NWs and NPs as an exploratory platform, we show that the synergistic effect between rapid charge transport and high surface area leads to a high performance photoelectronic formaldehyde sensor that exhibits a detection limit of as low as 5 ppb and a response of 1223% (at 10 ppm), which are, respectively, over 100 times lower and 20 times higher than those of conventional NPs-based device. Our work establishes a foundational pathway toward a better photoelectronic system by materials design.

Design of an ultra-sensitive gold nanorod colorimetric sensor and its application based on formaldehyde reducing Ag+

HCHO could reduce Ag⁺ to Ag on the surface of AuNRs to form Au core–Ag shell nanorods (Au@Ag↓NRs) in AuNRs–Ag⁺–HCHO system, which caused LPAB of AuNRs to redshift. Thus, a responsive AuNRs colorimetric sensor for the detection HCHO has been developed.