Ni-doped ZnO nanowire arrays (Ni–ZnO NRs) with different Ni concentrations are grown on etched fluorine-doped tin oxide electrodes by the hydrothermal method. The Ni–ZnO NRs with a nickel precursor concentration of 0–12 at. % are adjusted to improve the selectivity and response of the devices. The NRs’ morphology and microstructure are investigated by scanning electron microscopy and high-resolution transmission electron microscopy. The sensitive property of the Ni–ZnO NRs is measured. It is found that the Ni–ZnO NRs with an 8 at. % Ni precursor concentration have high selectivity for H2S and a large response of 68.9 at 250 °C compared to other gases including ethanol, acetone, toluene, and nitrogen dioxide. Their response/recovery time is 75/54 s. The sensing mechanism is discussed in terms of doping concentration, optimum operating temperature, gas type, and gas concentration. The enhanced performance is related to the regularity degree of the array and the doped Ni3+ and Ni2+ ions, which increases the active sites for oxygen and target gas adsorption on the surface.

Lead halide perovskites have drawn extensive attention on account of their fundamental role in the field of photoelectric detection. Nevertheless, the existence of toxic lead ions and the instability of lead-based perovskites greatly hamper their applications in mass production and commercialization. Herein, a hybrid photodetector based on the lead-free inorganic perovskite nanoflake (Cs 3 Sb 2 Br 9 NF)/monoradicular CdSe nanobelt (NB) has been successfully prepared. The hybrid nanostructures promote the effective separation of electron−hole pairs, thus dramatically improving the photoelectric performance. Meanwhile, the Cs 3 Sb 2 Br 9 NF/CdSe NB photodetector possesses a wideband spectral response from 300 to 780 nm and shows a higher responsivity (174 A/W), external quantum efficiency (4.8 × 10 4 %), and photodetectivity (1.1 × 10 14 Jones) under 448 nm illumination. Overall, these superior photoelectric properties confirm that the Cs 3 Sb 2 Br 9 NF/CdSe NB is a kind of hybrid optoelectronic device with practical application in civilian and military fields.

For real-application gas sensors, high performances (response, selectivity, response/recovery time and stability) are demanded. An effective strategy is applying nanomaterials in gas sensors. In this study, the anatase TiO2 flower-like nanomaterials (FLNMs) are prepared through a one-step hydrothermal method which exhibit high-performance toward acetone vapor. TiO2 FLNMs sensors property are characterized at optimal working temperature of 330 °C with selectivity (acetone), response (S = 33.72 toward 250 ppm acetone), linear dependence (R2 = 0.9913), response/recovery time (46/24 s toward 250 ppm acetone) and long-term stability (30 days). These demonstrate that TiO2 FLNMs get a high performance for acetone sensor. Moreover, the limit of detection of acetone is 0.65 ppm which is lower than that of exhaled air for diabetes (0.8 ppm), indicating that TiO2 FLNMs gas sensor gets potential application in medical diagnosis.

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