Heterostructure colloidal crystal for light activated hydrogen sensing at low temperature

The uniformity of porous heterostructures developed for gas sensing is essential to achieve repeatability in both sensor output and fabrication processes. Colloidal lithography has previously proven to be an excellent approach in obtaining seamless/uniform composite structures as sensitive layers in various applications including chemical/gas sensing. Among various gas species, detection of low concentrations of hydrogen is vital for many applications such as energy and transport industries as clean fuel; medical industries as marker for gastrointestinal disorders and chemical/manufacturing industries in producing ammonia. Due to its explosive nature, researchers are focusing on developing hydrogen sensors that operate at low temperatures, however critical performance aspects such as selectivity and sensitivity are proving to be a challenge. In this study, we report light-assisted amperometric gas sensors (AGS) utilizing tailored sensitive layers comprising long-range ordered colloidal crystal of core-shell TiO2/MoS2 heterojunction-based nanostructures specifically designed for H2 sensing applications at room temperature. The effect of various external stimuli such as electrical bias and light activation were studied while operating the developed AGS at 33 °C. The results showed > 99% repeatability with excellent selectivity (87%) while illuminating with 365 nm (2024 µW.cm−2) light under 9 V bias. At these optimum conditions, the sensor also showed a detection limit < 44 ppm, making it highly applicable in many industries requiring passive and low temperature operation.