Surface electronic structure modulation of PdO/SnO2 through loading Pd for superior hydrogen sensing performance

Modulating the surface electronic structure of metal oxides is crucial for enhancing their gas-sensing performance, with gradient energy level structures offering effective regulate. However, the mechanism underlying their impact on hydrogen sensing remains unclear. This study constructed mesoporous Pd-PdO/SnO 2 double-shelled microspheres with gradient energy levels via a soft-template method, precisely tuning the surface electronic structure of SnO 2 . The architecture integrates high surface area (30.9 m 2 /g), ordered mesopores (17.9 nm), and Schottky barrier modulation at PdO(5.04 eV)-SnO 2 (4.92 eV) interfaces, establishing unidirectional electron transfer pathways that amplify charge separation efficiency by 7.3×. The optimized 5 at.% Pd-PdO/SnO 2 sensor achieves high H 2 response (R a /R g  =  [email protected]  ppm) at 162.5℃ with ultrafast kinetics (0.2 s response/4.8 s recovery), a three-order detection span (0.5–8000 ppm), and humidity tolerance (91 % accuracy@80 %RH via machine learning). Theory calculation reveals the gradient structure enhances H 2 adsorption energy (−0.76 eV vs. PdO/SnO 2 : −0.02 eV) and boosts interfacial charge transfer by 46× (0.276 e vs. 0.006 e), driven by synergistic mechanisms: (1) Sn 5 s/p-dominated conduction band electron enrichment (68 % DOS increase near Fermi level), and (2) Pd catalytic activation lowering H 2 dissociation barriers from 1.32 eV (SnO 2 ) to 0.85 eV. This electronic-structure engineering paradigm establishes a roadmap for intelligent gas sensors.