A highly selective, efficient hydrogen gas sensor based on bimetallic (Pd–Au) alloy nanoparticle (NP)-decorated SnO2 nanorods

Abstract

The surging worldwide demand for hydrogen highlights the crucial need for advanced detection technologies, essential for enhancing safety and optimizing utilization across various applications. In this context, we have constructed a highly sensitive hydrogen gas sensor based on SnO₂ nanorods decorated with bimetallic (Pd–Au) alloy nanoparticles (NPs) (Pd–Au@SnO₂). The material synthesis (Pd–Au@SnO₂) was achieved through a hybrid approach involving a hydrothermal treatment and an in situ ascorbic acid reduction process. Various compositions of SnO₂ nanorods were prepared by tailoring the bimetallic content of Pd and Au, which was accomplished by adding different volume ratios of their respective precursor solutions. Among the various synthesized combinations, the composition of SnO₂ (S1-0.5) with bimetallic decoration (Pd–Au) in a volume ratio of 1 : 0.5 demonstrates superior gas sensing capabilities towards hydrogen (25–500 ppm) within the temperature range 100–200 °C. The S1-0.5 sensor shows a response (R_a/R_g) of 46.4 towards 100 ppm of hydrogen at 175 °C, which is 42.7 fold higher than the bare SnO₂ (S0-0) and 2.7 fold higher than Pd decorated SnO₂ (S1-0). The excellent gas sensing performance of the S1-0.5 sensor is due to the strong catalytic effect and the synergetic effect of both Pd and Au. The response and recovery times of the S1-0.5 sensor were measured to be 19 s and 302 s, respectively. Furthermore, the S1-0.5 sensor also showed a high selectivity toward gaseous NH₃, CO₂, CO, and ethanol with a high stability and repeatability.