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, <i>in-situ</i> Raman, <i>ex-situ</i> 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.