CuO Nanoparticles/Ti₃C₂T_x MXene Hybrid Nanocomposites for Detection of Toluene Gas

Abstract

Toluene is one of the harmful volatile organic compounds (VOCs) for both human health and environments. Thus, to prevent the hazardous effect of toluene, fast detection at an early stage is needed. CuO shows the merit for a wide range responsivity to VOCs but suffers from small response value, slow response/recovery speeds, and low durability. Herein, we report a facile preparation of CuO/Ti 3 C 2 T x MXene hybrids via electrostatic self-assembly. The CuO nanoparticles (∼7 nm) were uniformly dispersed on the surface and the interlayers of the Ti 3 C 2 T x MXene, forming hybrid heterostructures. The CuO/Ti 3 C 2 T x MXene exhibited the improved toluene gas sensing response (R g /R a ) of 11.4, which is nearly 5 times higher than that of the pristine CuO nanoparticles (2.3) to 50 ppm of toluene at 250 °C. Due to the different work function (Φ), the Schottky junction was established at the interface of CuO/Ti 3 C 2 T x MXene, acting as a hole trapping region (HTR) at the Ti 3 C 2 T x MXene side. Compared to other hybrid 2D materials such as MoS 2 and rGO, which possess a higher work function, the CuO/Ti 3 C 2 T x MXene maintained better toluene sensing performance. Thus, the work function is critical for designing a high sensing performance of hybrid metal oxides/2D materials. The hybridization of CuO with Ti 3 C 2 T x MXene improved not only enhancement of the response time but also the selectivity and the responses (270 s) and recovery times (10 s) compared with those of CuO, due to high conductivity of the metallic phase in Ti 3 C 2 T x MXene. Such excellent performance showed the promising applications of metal oxides/2D hybrid materials for VOCs gas sensing.

Experimental and Theoretical Advances in MXene-Based Gas Sensors

“…The response of the W 18 O 49 /Ti 3 C 2 T x sensor with more than 2 wt % of MXene decayed due to the presence of −F functional groups that were not fully eliminated after the solvothermal process, indicating the deteriorating effect of the −F functional group on the gas-sensing performance of MXene-based sensors. Due to the nonpolar structure of C-containing gas molecules such as toluene, MXenes do not show a good response to them. ,, Hermawan et al described the fabrication of hybrid heterostructures of CuO nanoparticles/Ti 3 C 2 T x MXene via electrostatic self-assembly. It was reported that CuO nanoparticles have an average size of 7 nm and were uniformly distributed over the interlayers and surface of Ti 3 C 2 T x MXene (Figure c).…”

Prospects and Challenges of MXenes as Emerging Sensing Materials for Flexible and Wearable Breath‐Based Biomarker Diagnosis

“…f) gas sensing linear fitting of R −1 versus C −1 based on the Langmuir isotherm model; g) response/recovery times; h) selectivity of CuO/Ti 3 C 2 T x -30 wt% to 50 ppm of tested gas; and i) relationship of response value with specific surface area. Adapted with permission [143]. Copyright 2020, American Chemical Society.…”

Inorganic-Diverse Nanostructured Materials for Volatile Organic Compound Sensing

“…Similar to microstructure-based volatile hydrocarbon vapors quantification (example: Sn 2+ doped NiO microspheres in Xylene detection with sub-ppm LOD) [ [390][391][392][393][394][395][396][397]. Wherein, Ag/Bi 2 O 3 nanocomposite and Graphene/SnO 2 NPs nanocomposite were found to perform remarkably in terms of their operation temperature (at room temperature) [394,397].…”

“…Similar to microstructure-based volatile hydrocarbon vapors quantification (example: Sn 2+ doped NiO microspheres in Xylene detection with sub-ppm LOD) [ 389 ], nanocomposites, such as Pd/PdO/S-SnO 2 nanocomposite film, rGO/Co 3 O 4 nanocomposite, WO 3 decorated TiO 2 NPs nanocomposite, BGQD/Ag–LaFeO 3 nanocomposite, Ag/Bi 2 O 3 nanocomposite, AgO loaded LaFeO 3 nanocomposite, CuO NPs-Ti 3 C 2 Tx MXene nanocomposite, and Graphene/SnO 2 NPs nanocomposite were effectively applied in the detection of hydrocarbons as detailed in Table 5 [ 390 , 391 , 392 , 393 , 394 , 395 , 396 , 397 ]. Wherein, Ag/Bi 2 O 3 nanocomposite and Graphene/SnO 2 NPs nanocomposite were found to perform remarkably in terms of their operation temperature (at room temperature) [ 394 , 397 ].…”