Synergistic effects of Pd single atoms and nanoclusters boosting SnO2 gas sensing performance

Abstract

Tin(IV) oxide-supported Pd is a promising heterogenous catalyst for CO oxidation relevant for environmental cleanup reactions. In this study, an atomically dispersed Pd catalyst on SnO₂ (ADC Pd/SnO₂) hybrid material is successfully synthesized via a straightforward wet chemistry method and is found to exhibit superior performance toward CO sensing. Ex situ EXAFS analysis confirms the formation of single Pd atoms and small Pd nanoclusters stabilized on the SnO₂(110) surface. The material exhibits high efficiency in generating adsorbed O₂⁻ as well as high activity in catalyzing CO oxidation at low temperatures, resulting in exceptional sensitivity and selectivity toward CO in comparison to pure SnO₂ and Pd nanoparticles loaded on SnO₂ respectively. In situ FTIR measurements unravel CO adsorption kinetics on ADC Pd/SnO₂ under reaction conditions, and a possible sensing mechanism is put forth in which CO is transformed into CO₂ by reaction with active oxygen species; and concurrently, carbon-related species (bicarbonates and carbonates) are formed and decomposed into CO₂.