Single‐Atom Pt Loaded on MOF‐Derived Porous TiO₂ with Maxim‐Ized Pt Atom Utilization for Selective Hydrogenation of Halonitro‐benzene

Abstract

The location control of single atoms relative to supports is challenging for single-atom catalysts, leading to a large proportion of inaccessible single atoms buried under supports. Herein, a "sequential thermal transition" strategy is developed to afford single-atom Pt preferentially dispersed on the outer surface of TiO₂. Specifically, a Ti-MOF confining Pt nanoparticles is converted to Pt_NPs and TiO₂ composite coated by carbon (Pt_NPs&TiO₂@C-800) at 800 °C in N₂. Subsequent thermal-driven atomization of Pt_NPs at 600 °C in air produce single-atom Pt decorated TiO₂ (Pt₁/TiO₂-600). The resulting Pt₁/TiO₂-600 exhibits superior p-chloroaniline (p-CAN) selectivity (99 %) to Pt_NPs/TiO₂-400 (45 %) and much better activity than Pt₁@TiO₂-600 with randomly dispersed Pt₁ both outside and inside TiO₂ in the hydrogenation of p-chloronitrobenzene (p-CNB). Mechanism investigations reveal that Pt₁/TiO₂-600 achieves 100 % accessibility of Pt₁ and preferably adsorbs the -NO₂ group of p-CNB while weakly adsorbs -Cl group of p-CNB and p-CAN, promoting catalytic activity and selectivity.