High-performance optical hydrogen sensor based on photonic crystal assembled by Ni-doped CAU-1 and TiO2

Hydrogen (H 2 ) leakage poses critical safety hazards and environmental risks in clean energy systems, driving urgent demands for cost-effective hydrogen sensors with high sensitivity, high selectivity, and rapid response time. Herein, high-performance hydrogen sensor based on photonic crystals (PCs) assembled by CAU-1, nickel (Ni) -doped CAU-1, and TiO 2 are prepared. Comparing with the CAU-1/TiO 2 and CAU-1Ni 15% /TiO 2 PC sensors, CAU-1Ni 25% /TiO 2 PC sensor shows a high sensitivity of hydrogen response to be 0.083 nm/ppm with a good linear relationship in the concentration range of 9–90 ppm hydrogen. Density-functional theory (DFT) adsorption energy calculations quantitatively validate the enhanced hydrogen adsorption capacity through Ni-induced electronic structure modulation. The CAU-1Ni 25% /TiO 2 PC sensor exhibits an ultrafast optical response time of 3 s and a recovery time of 12 s with exceptional repeatability and reliability. Moreover, the CAU-1Ni 25% /TiO 2 PC sensor displays exceptional selectivity toward H 2 by comparing with CO 2 , NH 3 , and O 2 , which is important for practical hydrogen detection applications. This work presents incorporating Ni into CAU-1 enhances hydrogen adsorption energy through electronic structure modulation, enabling the CAU-1Ni 25% /TiO 2 PC to achieve rapid optical sensing response to hydrogen, which establish a new pathway for developing high-efficiency photonic crystal-based optical hydrogen sensors.