Ultrafine Pd nanoparticles-decorated TiO2 three-dimensional (3D) hybrid aerogel with large specific surface areas and highly interconnected porous networks for hydrogen sensing

A hybrid aerogel structure for hydrogen sensing was produced and tested, which consists of Pd nanoparticles decorated on a TiO2 aerogel skeleton structure with large specific surface areas and high porosity. The effects of decorated with different contents of Pd nanoparticles on the microstructure of anatase TiO2 aerogel and the hydrogen response characteristics were investigated. The contribution of the doping of Pd nanoparticles to the specific selectivity of the anatase phase TiO2 aerogel for hydrogen sensing was investigated. Benefiting from highly interconnected porous networks of aerogel, ultra-large specific surface area, and homogeneous Pd nanoparticles dispersion, the resulting Pd nanoparticle-decorated TiO2 3D hybrid aerogel hydrogen sensors express high hydrogen sensing performance. The response was 4.8 toward 100 ppm hydrogen at the optimal working temperature of 325 °C, with a short response time (<2 s), short recovery time (<22 s), and high selectivity and long-term stability. A hydrogen-sensitive mechanism is proposed in which metal atom doping causes more oxygen defects in metal oxide semiconductor lattice. The approach of constructing aerogel network structures by decorating metal nanoparticles on metal oxide semiconductors provides a new way to develop gas sensors.