The supported metal catalysts on scaffolds usually reveal multiple active sites, resulting in the occurrence of side reaction and being detrimental to the achievement of highly consistent catalysis. Single atom catalysts (SACs), possessed with highly consistent single active sites, have great potentials for overcoming such issues. Herein, the authors used SACs to modulate kinetic process of gas sensitive reaction. The supported Pd SACs, established by a metal organic frameworks-templated approach, promoted greatly the detection capacity to hydrogen sulfide (H2 S) gas with a very high sensitivity and selectivity. Density functional theory calculations show that the supported Pd SACs not only increased the number of electrons transferring from H2 S molecules to Pd SACs, but strengthened surface affinity to H2 S. Moreover, the HS bonds of H2 S molecules absorbed on Pd atomic sites are more likely to be dehydrogenated directly into sulfur species. Significantly, quasi in situ XPS analysis confirmed the presence of sulfur species during H2 S detection process, which may be a major cause for such detection signal. Based on these results, a suitable sensing principle for H2 S gas driven by Pd SACs was put forward. This work will enrich catalytic electronics in chemiresistive gas sensing.
Keywords: DFT calculations; H 2S; Pd single atoms; chemiresistive gas sensing; kinetic reaction process.
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