Tailoring uniform PdO dispersion on hierarchical mesoporous SnO2 nanospheres for enhanced hydrogen sensing performance

Hydrogen (H 2 ) is widely regarded as a clean energy carrier, yet its flammability underscores the need for highly sensitive and rapid gas sensors to ensure safe leak detection. Conventional noble-metal-modified SnO 2 sensors often suffer from slow sensing kinetics and high material costs due to poor noble metal dispersion and excessive doping content. Herein, we design and synthesize the SnO 2 -PdO composite with uniform nanosphere structure by a facile one-step template strategy. The optimized SnO 2 -PdO-2% sensor achieves excellent sensing performance with only 2 mol% Pd loading, benefiting from its mesoporous architecture, high specific surface area, and efficient SnO 2 /PdO heterointerfaces, which promote charge transfer and enhance the adsorption of active oxygen species. The sensor operates at a relatively low temperature of 180 °C with an ultrafast response time of 1 s and recovery time of 6 s. In addition, a theoretical detection limit of 54 ppb is obtained. The sensor also demonstrates preferential hydrogen sensing behavior, good long-term stability, and excellent reproducibility. This work provides a highly Pd-efficient strategy for designing high-performance semiconductor oxide sensors for rapid and reliable hydrogen leak detection.