Hydrogen sensing performance of atmospheric plasma sprayed tin dioxide coating

As a potential source of clean energy, hydrogen (H-2) is considered as a promising fuel for internal combustion engines. Being colorless, odorless, and highly explosive gas; detection of H-2 using a cost effective sensor is important. In the present work, atmospheric plasma sprayed (APS) tin dioxide (SnO2) coating on alumina substrate was used for hydrogen (H-2) sensing. For steam reforming of ethanol, its decomposition on metal surface leads to the formation of CH4 and CO as well. Therefore, sensing characteristics of plasma sprayed SnO2 coating were also investigated for carbon monoxide (CO) and methane (CH4) gases. The plasma sprayed coating exhibited satisfactory H-2 sensing characteristics in terms of response %, response time, and repeatability over elongated duration. Up to 250 degrees C, SnO2 coating was found to be insensitive towards CH4 sensing and cross sensitive only to CO gas. Assuming Langmuir adsorption isotherm we have fitted the conductance transients of H-2 and CO to estimate the heat of adsorption (Q) and activation energy (Ea) as a function of concentration for these gases. Irrespective of the test gas concentration, the estimated activation energy towards H-2 sensing was lower as compared to that of CO. As compared to CO, the higher response % of SnO2 sensor towards H-2 sensing was explained to be due to its lower activation energy of adsorption. To the best of authors' knowledge, this is the first report highlighting the H-2 sensing performance of plasma sprayed SnO2 coating. We have proposed that atmospheric plasma sprayed large area SnO2 coating can be utilized as a catalyst in ethanol reforming process together with the detection of H-2, CO and CH4 gases as reaction products. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.