Very diverse two-dimensional (2D) materials have bloomed in NO2 gas sensing applications, which provides new opportunities and challenges in function oriented gas sensors. In this work, a 2D/2D/2D structure of the Ti3C2Tx@TiO2@MoS2 composite was well designed via a facile one-step hydrothermal route, in which TiO2 nanosheets are in situ grown on ultrathin and highly conductive Ti3C2Tx MXene. Simultaneously, the few-layer and vertically oriented MoS2 nanoflakes rich in active edge-sites were uniformly distributed in the composite. Ti3C2Tx MXene and MoS2 act respectively as the electron reservoir and main sensitive material. The strong interfacial contact in different components facilitated the transfer of charge carriers and their spatial separation. Integrating the unique structural and electronic properties, the as-prepared Ti3C2Tx@TiO2@MoS2 sensor exhibited a remarkable gas sensing performance at room temperature (Ra/Rg = 55.16, 50 ppm NO2), which is 7.3, 3.8 and 2.1 times higher than that of pristine MoS2, TiO2@MoS2 and Ti3C2Tx@MoS2 composites, respectively. It also achieved ultrafast response time (1.8 s), more than 90% recoverability, low detection limit (23 ppb), dedicated selectivity and as long as eight-week stability.
Jianye Shi,Jin Chen,Xinle Wang,Zhikang Liu,Yuzhao Ma,Xiaofeng Yang,Meidan Que,Yanjun Li
Developing a lightweight microwave absorbing materials with high absorption capacity and wide absorption bandwidth at low thickness is a perennial challenge in practical applications in the microwave absorption (MA) field. Herein, sandwich-like heterogeneous Ti 3 C 2 T x /TiO 2 /Fe 3 O 4 /Fe are designed by synergistically incorporating dielectric-magnetic components with a simple solvothermal method and post-annealing. The sandwich-like heterogeneous interface produces sufficient conduction loss for Ti 3 C 2 T x /TiO 2 /Fe 3 O 4 /Fe, with TiO 2 crystals and amorphous carbon anchored on its surface to enhance interface polarization and Debye relaxation. Additionally, the presence of Fe nanoparticles induces magnetic loss, including natural resonance and eddy current loss. By bidirectionally regulating the ratio of Ti 3 C 2 T x and Fe 3 O 4 , the minimum reflection loss (RL min ) value reaches − 64.6 dB at 17.49 GHz with a 1.48 mm thickness, and the corresponding effective absorption bandwidth (EAB, RL < −10 dB) is 4.59 GHz (13.41–18 GHz). The results suggest that the exceptional EMW absorption performance of composites can be attributed to the dielectric-magnetic synergistic effect and sandwich-like heterostructures . This study offers a rational approach for synthesizing ultrathin and lightweight Ti 3 C 2 T x -based absorbers.
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