Surface Stabilization of Single-Atom Catalyst on Metal Oxide Derived by Metal Hydroxide-Organic Frameworks

Single-atom catalysts (SACs) have been attracted as promising sensitizers in gas sensors due to their high catalytic activity and efficient atomic utilization. To synthesize SACs-anchored materials, metal-organic frameworks (MOFs) have been widely employed as sacrificial templates owing to their structural flexibility and high surface area. However, in this approach, only carbon-based materials have been allowed as target products since structural deformation between ligand and metal nodes should be sufficiently minimized to stabilize SACs during the transformation. Herein, we propose a novel synthetic route to fabricate metal-oxide-supported SACs by utilizing metal hydroxide-organic frameworks (MHOFs) with noble metal chelated linkers as templates. Highly ordered metal hydroxide layers and numerous π-stacked MHOFs linkers provide stable binding sites for SACs during the complete transformation from MOFs to metal oxide. Thereby, a high concentration of SACs can be stabilized on metal oxide without aggregation and doping of catalysts. The resultant Pt SACs-anchored NiO showed enhanced activity for chemiresistive sensing of H₂S. Furthermore, the high structural diversity of MHOFs would allow the extension of this approach to other catalysts and metal oxides for targeting various analytes.