Single-Atom Pt Loaded on MOF-Derived Porous TiO with Maxim-Ized Pt Atom Utilization for Selective Hydrogenation of Halonitro-benzene.

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 TiO. Specifically, a Ti-MOF confining Pt nanoparticles is converted to Pt and TiO composite coated by carbon (Pt&TiO@C-800) at 800 °C in N. Subsequent thermal-driven atomization of Pt at 600 °C in air produce single-atom Pt decorated TiO (Pt/TiO-600). The resulting Pt/TiO-600 exhibits superior p-chloroaniline (p-CAN) selectivity (99 %) to Pt/TiO-400 (45 %) and much better activity than Pt@TiO-600 with randomly dispersed Pt both outside and inside TiO in the hydrogenation of p-chloronitrobenzene (p-CNB). Mechanism investigations reveal that Pt/TiO-600 achieves 100 % accessibility of Pt and preferably adsorbs the -NO group of p-CNB while weakly adsorbs -Cl group of p-CNB and p-CAN, promoting catalytic activity and selectivity.