Effect of carbon doping on gas sensing properties of molybdenum oxide nanoneedles

This work presents gas sensing study of carbon doped molybdenum oxide (MoO_x) nanoneedles prepared by reactive sputtering process. The MoO_x gas sensing layers have been achieved with varying carbon concentration. Structural and morphological characterization by means of SEM, TEM and XRD indicate that carbon is incorporated into MoO_x nanoneeles but carbon doping does not considerably affect surface morphology and crystal quality. Electrical characterizations highlight interesting behaviors for the layer tested. The MoO_x film´s conductance decreases by more than one order of magnitude with carbon doping. As carbon content increases, acetone and particularly ethanol responses are significantly improved by more than an order of magnitude. In contrary, hydrogen and methane response are low and relatively insensitive to carbon content. Therefore, carbon doping makes MoO_x nanoneedles more selective toward volatile organic compounds (VOCs) than hydrocarbon gases.