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.