Fabrication of highly dispersed Pt NPs in nanoconfined spaces of as-made KIT-6 for nitrophenol and MB catalytic reduction in water

Platinum-based catalysts are highly promising for versatile catalytic reduction reactions. However, the performance is severely dependent on the dispersion state of platinum nanoparticles (Pt NPs), while regulation of Pt NPs via an efficient strategy remained a pronounced challenge. In this contribution, solid-state fabrication (SSF) strategy was developed to make highly dispersive Pt NPs in the nanoconfined spaces of 3-dimentional (3D) mesoporous silica (MS) KIT-6 (Korea Advanced Institute of Science and Technology-6). The Pt precursor was introduced directly into the nanoconfined spaces between the template and silica walls of as-made KIT-6 (AK). Subsequent calcination in air followed by H2 reduction allows template P123 removal and Pt precursor reduction to Pt0 in a single step instead of multiple ones reported earlier in conventional fabrication strategies. This results in formation of smaller size Pt NPs in AK making Pt containing catalysts highly active. Characterization results revealed that the confined spaces of AK can disperse 1.0 wt% of Pt well (PtAK-1.0) with particle size of 2.8 nm, while serious aggregation and/formation of larger Pt NPs take place on PtCK-1.0 synthesized by conventional method. We also demonstrated that PtAK-1.0 is highly active for p-nitrophenol (P-NP) catalytic reduction and degradation of Methylene blue (MB) with reaction rate constant of 0.2804 and 0.164 min-1, respectively, which is much better than that of PdCK-1.0 and other reported catalysts. Furthermore, catalytic activity of PtAK-1.0 after regeneration can be well recovered without major loss. Facile preparation, high catalytic activity and good reusability enable the present materials highly suitable as catalysts for waste water treatment.