Low power combustible gas sensors using a thermocouple design are provided. In one aspect, a combustible gas sensor includes: at least one first electrode; at least one second electrode formed from a dissimilar material from the first electrode; and a catalytic material at an active reaction junction between the first electrode and the second electrode, wherein the active reaction junction between the first electrode and the second electrode forms a thermocouple. A sensing device is including, e.g., multiple sensors, and a method for sensing combustible gas using the present sensors are also provided.