Low energy N⁺ ion beam induced effect on structural and morphological properties of Ti₃C₂ MXene nanosheet towards enhanced hydrogen gas sensing applications

MXene is a youngest member of two-dimensional (2D) materials community having controlled structure, unique composition and highly chemical active surface functionality. The layered structure of Mxene possesses high surface area, high porosity, high metallic order conductivity, flexibility, which offers them as a suitable and potential material for detection of environmental gases and analytes. In the present study, Ti₃C₂ MXene nanosheets were synthesized by selectively etching the Al layers from Ti₃AlC₂ MAX phases using hydrofluoric acid (HF) under prolonged stirring. The chemiresistive type sensor configuration was prepared, where synthesized Ti3C2 nanosheets were used as active layer to detect the hydrogen (H2) gas at room temperature. The prepared samples were irradiated by 10 keV N⁺ ion at three different flounces of 1×10¹⁵, 5× 10¹⁵ and 1× 10¹⁶ ions cm⁻² using indigenously developed low energy ion beam table top accelerator. The comparative study have been done to analyse the impact of ion irradiation on skelton, surface changes, and H2 gas sensing of Ti3C2 MXene nanosheets after and before irradiation. It was observed that after irradiation, the sensor exhibited a higher and faster response, with the response magnitude increasing linearly with ion fluence. The maximum response value reached 2.1 for the sensor irradiated at ion fluence of 1×10¹⁶ ions cm⁻², compared to a value of 1.37 for the pristine Ti3C2 MXene sensor. After irradiation the sensor show a faster response and recovery in comparison to that pristine MXene thin film sensor and optimized response and recovery time performance were found 98 s and 109 s, respectively for the sample irradiated at higher ion fulence (1×10¹⁶ ion cm⁻²). The findings demonstrate that the ion irradiation has a significant effect on the structural and morphological properties of MXene nanosheets, which in turn enhances their gas sensing performance and with increasing ion fluence, the sensor demonstrates good short as well as long term stability, exhibiting a consistent response pattern and faster response as well as recovery in comparison to pristine Ti3C2 MXene sensor. X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were employed to investigate the surface morphology and microstructural properties of the fabricated MXene samples.