MoSe2xTe2–2x alloy for hydrogen gas detection

This study presents one of the first detailed investigation into the out-of-plane growth of two-dimensional MoSe 2x Te 2–2x for three distinct Se:Te compositions, yielding the samples MoSe 0.46 Te 1.55 , MoSe 0.55 Te 1.45 , and MoSe 0.64 Te 1.35 . Scanning electron microscopy reveals the morphological evolution, showcasing nanoflakes predominantly grown in a random out-of-plane orientation. Raman spectroscopy confirms the crystal structure of MoSe 2x Te 2–2x samples, with no detectable traces of MoO 3 or MoO 2 precursors. Distinctive peaks validate the presence of MoSe 2x Te 2–2x , while spectral shifts suggest at compositional variations. Conductive-Atomic Force Microscopy (C-AFM) was used to quantify current flow between a diamond-doped AFM tip and the sample. Additionally, the resistances of compositions MoSe 0.46 Te 1.55 , MoSe 0.55 Te 1.45 , and MoSe 0.64 Te 1.35 were characterized, yielding median values of 108.0 Ω, 25.4 kΩ, and 240.0 kΩ, respectively, indicating diverse electrical properties associated with Se content. Notably, the sample with the highest Se content exhibits increased resistivity as anticipated, consistent with XRD spectra results. Finally, gas-sensing performance is evaluated by assessing electrical resistance variations before and after exposure to H 2 gas at various temperatures, revealing significant changes indicative of enhanced charge flow upon H 2 exposure. Map of resistance for the three Te:Se ratios grown, measured by conductive AFM. d) Average value of the current-voltage curve for the three concentrations. e) Current-voltage characteristics immediately after exposure to an H 2 atmosphere for the MoSe 0.55 Te 1.45 sample at different temperatures. f) Response of the MoSe 0.55 Te 1.45 sample at different temperatures at 0.5 V, and comparison of the response to the other two concentrations at 150°C. • Two-dimensional nanostructures of MoSeTe grown out-of-plane at three different concentrations. • As the Se content increases, there is a corresponding rise in resistance. • After exposure to H 2 gas, a decrease in electrical resistance was observed in the samples.