We report the fabrication of a novel metal−organic framework (MOF)−polymer mixed-matrix flexible membrane for the detection of hydrogen sulfide (H 2 S) gas at room temperature. This high-performance gas sensor is based on MOF-5 microparticles embedded on a conductivity-controlled chitosan (CS) organic membrane. The conductivity of the organic membrane is controlled by blending it with a glycerol ionic liquid (IL) at different concentrations. The sensor showed a remarkable detection sensitivity for H 2 S gas at a concentrations level as low as 1 ppm at room temperature. The MOF-5/CS/IL gas sensor demonstrates a highly desirable detection selectivity, fast response time (<8 s), recovery time of less than 30 s, and outstanding sensing stability averaging at 97% detection with 50 ppm of H 2 S gas. This composite having high sensitivity, low-power consumption, and flexibility holds great promise for addressing current challenges pertinent to environmental sustainability.

The development of gas sensing devices to detect environmentally toxic, hazardous, and volatile organic compounds (VOCs) has witnessed a surge of immense interest over the past few decades, motivated mainly...

High-performance, room temperature-based novel sensing materials are one of the frontier research topics in the gas sensing field, and MXenes, a family of emerging 2D layered materials, has gained widespread attention due to their distinctive properties. In this work, we propose a chemiresistive gas sensor made from V2CTx MXene-derived, urchin-like V2O5 hybrid materials (V2C/V2O5 MXene) for gas sensing applications at room temperature. The as-prepared sensor exhibited high performance when used as the sensing material for acetone detection at room temperature. Furthermore, the V2C/V2O5 MXene-based sensor exhibited a higher response (S% = 11.9%) toward 15 ppm acetone than pristine multilayer V2CTx MXenes (S% = 4.6%). Additionally, the composite sensor demonstrated a low detection level at ppb levels (250 ppb) at room temperature, as well as high selectivity among different interfering gases, fast response-recovery time, good repeatability with minimal amplitude fluctuation, and excellent long-term stability. These improved sensing properties can be attributed to the possible formation of H-bonds in multilayer V2C MXenes, the synergistic effect of the newly formed composite of urchin-like V2C/V2O5 MXene sensor, and high charge carrier transport at the interface of V2O5 and V2C MXene.

Compared to traditional-metal oxide-based gas sensors (MOS), the progress of high-performance room-temperature (RT) gas-sensing materials has captivated a lot of interest in recent years. MXenes, two-dimensional (2D) transition-metal carbides/nitrides, have recently been discovered and gained tremendous consideration for gas sensing applications due to their superior chemical and physical properties. Herein, we successfully synthesized accordion-like Ti 3 C 2 T x MXene multilayers by a selective HF-etching method at 60 °C to be used as a chemiresistive sensor for acetone vapor. The fabricated sensor successfully detected acetone vapor at the parts per billion (ppb) level and showed a p-type sensing behavior. The limit of detection (LOD) of acetone vapor was about 250 ppb with a fast response time of 53 s. The sensor exhibited good repeatability, high selectivity toward acetone among other test gases, and excellent stability even after 4 months. The sensing mechanism was proposed in terms of the interaction between the charge carriers of accordion-like Ti 3 C 2 T x , multiple hydrogen bonding between different functional groups on the MXene surface, and acetone vapor species. The prepared sensor also showed high sensitivity toward acetone vapor at RT (23 °C); hence, it lends itself high potential as a breath sensor for diabetic patients.

Mixed matrix membranes (MMMs), possessing high porosity, have received extensive attention for gas sensing applications. However, those with high flexibility and significant sensitivity are rare. In this work, we report on the fabrication of a novel membrane, using Cu3(HHTP)2 MOF (Cu-MOF) embedded in a polymer matrix. A solution comprising a homogenous suspension of poly-vinyl alcohol (PVA) and ionic liquid (IL), and Cu-MOF solid particles, was cast onto a petri dish to obtain a flexible membrane (215 μm in thickness). The sensor membrane (Cu-MOF/PVA/IL), characterized for its structure and morphology, was assessed for its performance in sensing against various test gases. A detection limit of 1 ppm at 23 °C (room temperature) for H2S was achieved, with a response time of 12 s. Moreover, (Cu-MOF/PVA/IL) sensor exhibited excellent repeatability, long-term stability, and selectivity towards H2S gas. The other characteristics of the (Cu-MOF/PVA/IL) sensor include high flexibility, low cost, low-power consumption, and easy fabrication technique, which nominate this sensor as a potential candidate for use in practical industrial applications.