Exploiting Free-Standing p-CuO/n-TiO₂ Nanochannels as a Flexible Gas Sensor with High Sensitivity for H₂S at Room Temperature

Abstract

Hydrogen sulfide (H 2 S) is an extremely hazardous gas and is harmful to human health and the environment. Here, we developed a flexible H 2 S gas-sensing device operated at room temperature (25 °C) based on CuO nanoparticles coated with freestanding TiO 2 -nanochannel membranes that were prepared by simple electrochemical anodization. Benefiting from the modulated conductivity of the CuO/TiO 2 p−n heterojunction and a unique nanochannel architecture, the traditional thermal energy was innovatively replaced with UV irradiation (λ = 365 nm) to provide the required energy for triggering the sensing reactions of H 2 S. Importantly, upon exposure to H 2 S, the p−n heterojunction is destroyed and the newly formed ohmic contact forms an antiblocking layer at the interface of CuS and TiO 2 , thus making the sensing device active at room temperature. The resulting CuO/TiO 2 membrane exhibited a notable detection sensitivity for H 2 S featuring a minimum detection limit of 3.0 ppm, a response value of 46.81% against 100 ppm H 2 S gas, and a rapid response and recovery time. This sensing membrane also demonstrated excellent durability, long-term stability, and wide-range response to a concentration of up to 400 ppm in the presence of 40% humidity as well as outstanding flexibility and negligible change in electrical measurements under various mechanical stability tests. This study not only provides a new strategy to design a gas sensor but also paves a universal platform for sensitive gas sensing.

Solution-processed metal doping of sub-3 nm SnO2 quantum wires for enhanced H2S sensing at low temperature

“…8 Besides, H 2 S is regarded as an endogenous gas (sub-ppb level) related to disease diagnosis, 9 and thus the sensitive and selective detection of H 2 S is highly important. However, most H 2 S sensors require high operating temperatures, which are usually above 250 C. 10,11 Although some sensors can operate at lower temperatures, or even at room temperature, 12,13 they still suffer from poor limit of detection (LOD), which hampers their wide application for sub-ppb H 2 S detection.…”

“…However, most H 2 S sensors require high operating temperatures, which are usually above 250 °C. 10,11 Although some sensors can operate at lower temperatures, or even at room temperature, 12,13 they still suffer from poor limit of detection (LOD), which hampers their wide application for sub-ppb H 2 S detection.…”

Enhancement of Photoactivity of TiO2 for Potential Applications in CO2 Conversion and Water Splitting: A Hybrid Density Functional Theory Study

“…TiO 2 has attracted extensive attention as a promising multifunctional material for the generation of H 2 through water splitting, , degradation of environmental pollutants, lithium battery applications, , biomedical applications including cancer therapy, , photovoltaic applications, − CO 2 conversion, − and sensor applications. − However, due to a wide band gap (3.20 eV for anatase), TiO 2 shows photoactivity only under ultraviolet-light (UV) irradiation, which accounts for a smaller fraction (less than 5%) of solar energy . It is preferable that the band gap of the photocatalyst would be less than 3.0 eV for the effective utilization of sunlight.…”

Engineering CuMOF in TiO2 Nanochannels as Flexible Gas Sensor for High-Performance NO Detection at Room Temperature

“…In this study, we developed a selective chemiresistor gas sensor for detecting gaseous NO by using a specific MOFs-innanochannel 3D structure (Scheme 1), wherein ordered TiNCs act as the sensing scaffold for providing the resistance information. 19 This design effectively slowed the gas flow rate to allow adequate contact chances for the adsorption of a gaseous analyte onto the sensing surface. Through a suitable pore size of Cu 2+ -based MOFs containing Cu-TCA (H 3 TCA = tricarboxytriphenyl amine), NO gas molecules were selectively captured into the micropores of Cu-TCA.…”