Flexible and high-sensitivity sensor based on Ti3C2-MoS2 MXene composite for the detection of toxic gases.

It is vital to have high sensitivity in gas sensors to allow the exact detection of dangerous gases in the air and at room temperature. In this study, we used 2D MXenes and MoS2 materials to create a Ti3C2-MoS2 composite with high metallic conductivity and a wholly functionalized surface for a significant signal. At room temperature, the Ti3C2-MoS2 composite demonstrated clear signals, cyclic response curves to NO2 gas, and gas concentration-dependent. The sensitivities of the standard Ti3C2-MoS2 (TM_2) composite (20 wt% MoS2) rose dramatically to 35.8%, 63.4%, and 72.5% when increasing NO2 concentrations to 10 ppm, 50 ppm, and 100 ppm, respectively. In addition, the composite showed reaction signals to additional hazardous gases, such as ammonia and methane. Our findings suggest that highly functionalized metallic sensing channels could be used to construct multigas-detecting sensors that are very sensitive in air and at room temperature.

Efficient nickel or copper oxides decorated graphene-polyaniline interface for application in selective methanol sensing.

Graphene sheets decorated with nickel or copper oxides that were anchored on polyaniline (denoted as PANI-graphene/NiO and PANI-graphene/CuO) were prepared by a simple, easy to-control electrochemical method and applied as novel materials for sensitive and selective methanol sensing. The fabricated sensors exhibited good electrocatalytic activity, appropriate dynamic linear range (20-1300 mM), sensitivity (0.2-1.5 µA mM-1 cm-2) and excellent selectivity towards methanol. It should be highlighted from the selectivity tests that no significant interference was observed from ethanol and other alcohols. To our best knowledge, using inexpensive but efficient transition metals like Ni, Cu instead of Pt, Pd and their composites with PANI, graphene would be scientifically novel and practically feasible approach for sensor fabrication that could be potentially used to identify methanol adulteration in counterfeit alcoholic beverages.

Enzyme-less electrochemical displacement heterogeneous immunosensor for diclofenac detection.

We describe an electrochemical immunosensor based on functionalization of a working electrode by electrografting two functional diazonium salts. The first one is a molecular probe, diclofenac, coupled with an arylamine onto which a specific antibody is immobilized by affinity interactions; the second is a redox probe (a quinone) also coupled with an arylamine, able to transduce the hapten-antibody association into a change in electroactivity. The steric hindrance induced by the antibody leads to a current decrease upon binding of the antibody on the grafted molecular probe; conversely, when diclofenac is present in solution, a displacement equilibrium occurs between the target diffusing into the solution and the grafted probe. This leads to dissociation of the antibody from the electrode surface, event which is transduced into a current increase ("signal-on" detection). The detection limit is ca. 20 fM, corresponding to 6pgL-1 diclofenac, which is competitive compared to other label-free immunosensors. We demonstrate that the sensor is selective and is able to quantify diclofenac in tap water.