One-step photochemical deposition of PdAu alloyed nanoparticles on TiO₂ nanowires for ultra-sensitive H₂ detection

TiO₂ nanostructures are widely used for H₂ detection in scientific and technological research fields, but how to detect ppm-level H₂ in a timely and sensitive manner at room temperature remains challenging. In this work, TiO₂ nanowires were synthesized on a Ti foil substrate via the hydrothermal method, and then decorated with PdAu alloyed nanoparticles (NPs) via a one-step photochemical deposition method. What's more, the Pd/Au atomic ratio in alloyed NPs could be adjusted by just changing the Pd²⁺/Au³⁺ ratio in the precursor solution. H₂ sensing experiments indicate that sensitization with Pd or PdAu alloyed NPs makes TiO₂ nanowire films highly sensitive to ppm-level H₂ at room temperature. The role of Au in alloyed NPs is estimated by comparing the sensing performance of PdAu@TiO₂ with different Pd/Au ratios in alloyed NPs and references (e.g., TiO₂, Au@TiO₂ and Pd@TiO₂). The results indicate that the as-synthesized PdAu@TiO₂ with less than 25% Au in alloyed NPs exhibits higher sensitivity and a faster response than Pd@TiO₂, and plausible enhancement mechanisms of the Au component in alloyed NPs on the performance of PdAu@TiO₂ are also supplied.