Inhibiting Emulative Oxygen Adsorption via Introducing Pt-Segregated Sites into the Pd Surface for Enhanced H2 Sensing in Air

Pd-modified metal sulfide gas sensors exhibit excellent hydrogen (H2) sensing activity through spillover effects. However, the emulative oxygen adsorption often occupies an exposed Pd surface and thus limits the effective Pd–H interaction, impeding the H2 sensing performance in air. Herein, we develop an edge-rich Pt-shell/Pd-core structure to adjust the selective adsorption between oxygen and hydrogen for effective H2 sensing in an air atmosphere. Detailedly, through accurately regulating the rate of Pt deposition onto the icosahedron Pd surface, an edge-rich Pt-shell/Pd-core structure can be first achieved. It has been found that marginal Pt aggregations can segregate the oxygen molecules around the Pt species and induce easier Pt–O bonding, further guiding accessible Pd surfaces for effective Pd–H interactions, which can be verified by 1H ssNMR, in-situ Raman, ex-situ XPS, and density functional theory analyses. The final ZnS/PdPt sensor exhibits an ultrasensitive response (8608 to 4% H2) and a wide detected range (0.5 ppm-4%) in air, exceeding most reported hydrogen sensors.