Ultrahigh-response sensor based on hierarchical Pd-WO3 nanoflowers for rapid hydrogen detection

In this research, four tungsten trioxide materials were synthesized in precursor solutions with different pH values by hydrothermal method. Then, Pd nanoparticles were loaded on the hierarchical WO3 nanoflowers, which exhibited the best hydrogen sensitivity among the four as-synthesized materials. The hydrogen sensing test results demonstrated that the 0.50 at% Pd-WO3 sensor showed a fairly high response of 8658.98, a fast response/recovery time of 1/3 s and excellent selectivity to 500 ppm H2 at a working temperature of 150 °C, which properties were superior to previous WO3-based hydrogen sensors. The wonderful H2 sensing property was shown due to the increase of oxygen vacancies, adjustment of basic sensor resistance and spill-over effect of Pd. This work will provide a feasible strategy for designing H2 sensors with a fairly high response and fast response/recovery speed.