Single‐Atom Pt Loaded on MOF‐Derived Porous TiO2 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 TiO2. Specifically, a Ti‐MOF confining Pt nanoparticles is converted to PtNPs and TiO2 composite coated by carbon (PtNPs&TiO2@C‐800) at 800 °C in N2. Subsequent thermal‐driven atomization of PtNPs 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 PtNPs/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.