Temperature effect on hydrogen response for cracked carbon nanotube/nickel (CNT/Ni) composite film with horizontally aligned carbon nanotubes

We have developed a free lithography technique for hydrogen sensors using a cracked carbon nanotube/nickel (CNT/Ni) film with horizontally aligned CNT (HA-CNT). Cracks were induced on CNT/Ni film by simple hydrogen absorption and desorption processes to enhance sensor response using heat treatment. Gas sensing measurements taken with various concentrations (200–16,000 ppm) of hydrogen at room temperature revealed that the sensors based on cracks in CNT/Ni film exhibit promising results for response, response time, and recovery time. Compared to CNT/Ni sensors fabricated without heat treatment, the hydrogen sensors fabricated at 350 °C on cracked CNT/Ni film with HA-CNT exhibited a much more response (14.1% vs. 0.6%) and a faster response time (422 s vs. 1095 s) at 200 ppm H2 gas. The heat treatment method used to form cracks in the HA-CNT is relatively simple and effectively improved the response of CNT/Ni hydrogen sensors.