Surface-activated MoS2 via substitutional Re doping for NO2 sensing: Mechanistic insights from in situ Raman spectroscopy

초록

Transition metal dichalcogenides (TMDs) have attracted considerable attention as chemiresistive gas sensing materials owing to their layered structure and tunable electronic behavior for room temperature operation. However, their gas sensing performance remains limited by weak physisorption-dominated gas interactions, which result in insufficient charge transfer and sluggish reaction kinetics. In addition, the scarcity of surface adsorbed species hampers a mechanistic understanding of gas interactions in TMDs. Herein, we present substitutional Re doping as an effective strategy to sensitize MoS2 toward NO2 for on-site environmental monitoring. The incorporation of Re induced electron doping in MoS2 via reconfiguration of the d-orbital, concurrently modulating the electronic and lattice structure. As a result, the 0.6 mol% Re-doped MoS2 exhibited a 2.48-fold higher response (21.49%) toward 5 ppm NO2 compared to pristine MoS2 (8.65%) at room temperature. The enhanced NO2 sensing performance is mainly attributed to carrier concentration modulation and reactive sulfur vacancies that synergistically enhance NO2 interaction through electronic sensitization. Moreover, enhanced charge transfer-mediated electron-phonon interactions during NO2 exposure were evidenced by in situ Raman spectroscopy. By demonstrating the potential application of Re-doped MoS2 for on-site NO2 detection, this work reveals an effective doping strategy to activate TMD surfaces for superior chemiresistive gas sensing performance.

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