CdS/TiO₂ nano hybrid heterostructured materials for superior hydrogen production and gas sensor applications

In efforts to minimize environmental pollution and carbon-based gas emissions, photocatalytic hydrogen production and sensing applications at ambient temperature are important. This research reports on the development of new 0D/1D materials based on TiO₂ nanoparticles grown onto CdS hetersturctured nanorods via two-stage facile synthesis. The titanate nanoparticles when loaded onto CdS surfaces at an optimized concentration (20 mM), exhibited superior photocatalytic hydrogen production (21.4 mmol/h/g_cat). The optimized nanohybrid was recycled for 6 cycles up to 4 h, indicating its excellent stabity for a prolonged period. Also, the photoelectrochemical water oxidation in alkaline medium was investigated to offer the optimized CRT-2 composite with 1.91 mA/cm²@0.8 V vs. RHE (0 V vs. Ag/AgCl) that was used for effective room-temperature NO₂ gas detection exhibiting a higher response (69.16%) to NO₂ (100 ppm) at room temperature at the lowest detection limit of ∼118 ppb than the pristine counterparts. Further, NO₂ gas sensing performance of CRT-2 sensor was increased using UV light (365 nm) activation energy. Under the UV light, the sensor exhibited a remarkable gas sensing response quick response/recovery times (68/74), excellent long-term cycling stability, and significant selectivity to NO₂ gas. Due to high porosity and surface area values of CdS (5.3), TiO₂ (35.5), and CRT-2 (71.5 m²/g), excellent photocatalytic H₂ production and gas sensing of CRT-2 is ascribed to morphology, synergistic effect, improved charge generation, and separation. Overall, 1D/0D CdS@TiO₂ is proved to be an efficient material for hydrogen production and gas detection.