A selective nanoscale asymmetric gas sensor is disclosed, the sensor including a first electrode having a Schottky-type contact to a nanoengineered transducer with a barrier height between energy levels of the first electrode and the nanoengineered transducer; and a second electrode having an Ohmic contact to the nanoengineered transducer with a smaller or no barrier height than the first electrode. The first electrode can be palladium and the second electrode can be gold.