Catalytic thermoelectric hydrogen sensor with CoSb3 thermopile by single-step deposition on bare/textured glass

Abstract

Hydrogen sensors are required due to the flammability of hydrogen in air. Catalytic thermoelectric hydrogen sensors show promise because they provide direct voltage output from a temperature difference generated by the catalytic combustion of hydrogen. CoSb3 is a good thermoelectric material for energy harvesting and sensing. However, conventional CoSb3 thermopiles require the separate deposition of p- and n-type thermoelectric elements. This study proposes the surface roughness modification of a soda-lime glass substrate through the development of a textured glass surface to prepare a CoSb3 thermopile by single-step deposition. A Co-In-Sb stack with a SiO2 capping layer is deposited by an e-beam evaporator on bare/textured glass and thermally activated under room conditions, which produces a thermoelectric pair due to the partial release of volatile Sb from cracks developed in the rough layer formed on textured glass. A thermoelectric pair consists of a CoSb3 layer with a deficiency of Sb (n-type) on textured glass and that with an excess of Sb (p-type) on bare glass. A hydrogen sensor is made with CoSb3 thermopile with 41 thermoelectric pairs and a catalyst reservoir coated with hydrogen oxidation catalyst. The sensor shows a sensitivity of 13 mV for 1 % H2 in air at room temperature.