Inhibiting Emulative Oxygen Adsorption via Introducing\nPt-Segregated Sites into the Pd Surface for Enhanced H<sub>2</sub> Sensing in Air

Pd-modified\nmetal sulfide gas sensors exhibit excellent hydrogen\n(H<sub>2</sub>) sensing activity through spillover effects. However,\nthe emulative oxygen adsorption often occupies an exposed Pd surface\nand thus limits the effective Pd–H interaction, impeding the\nH<sub>2</sub> sensing performance in air. Herein, we develop an edge-rich\nPt-shell/Pd-core structure to adjust the selective adsorption between\noxygen and hydrogen for effective H<sub>2</sub> sensing in an air\natmosphere. Detailedly, through accurately regulating the rate of\nPt deposition onto the icosahedron Pd surface, an edge-rich Pt-shell/Pd-core\nstructure can be first achieved. It has been found that marginal Pt\naggregations can segregate the oxygen molecules around the Pt species\nand induce easier Pt–O bonding, further guiding accessible\nPd surfaces for effective Pd–H interactions, which can be verified\nby <sup>1</sup>H ssNMR, <i>in-situ</i> Raman, <i>ex-situ</i> XPS, and density functional theory analyses. The final ZnS/PdPt\nsensor exhibits an ultrasensitive response (8608 to 4% H<sub>2</sub>) and a wide detected range (0.5 ppm-4%) in air, exceeding most reported\nhydrogen sensors.