Silanol-Assisted High-Yield Nanofabrication of SnO<sub>2</sub> Single Crystals with Highly Tunable and Ordered Mesoporosity
Shoukang Xiao, Li Wang, Ze Qin, Xiao Chen, Liyu Chen, Yingwei Li, Kui Shen
Abstract
High Resolution Image Download MS PowerPoint Slide Highly ordered mesoporous materials with a single-crystalline structure have attracted broad interest due to their wide applications from catalysis to energy conversion/storage, but constructing them with good controllability and high yields remains a highly daunting task. Herein, we construct a new class of three-dimensionally ordered mesoporous SnO 2 single crystals (3DOm-SnO 2 ) with well-defined facets and excellent mesopore tunability. Mechanism studies demonstrate that the silanol groups on ordered silica nanospheres (3DO-SiO 2 ) can induce the efficient heterogeneous crystallization of uniform SnO 2 single crystals in its periodic voids by following the hard and soft acid and base theory, affording a much higher yield of ∼96% for 3DOm-SnO 2 than that of its solid counterpart prepared in the absence of 3DO-SiO 2 (∼1.5%). Benefiting from its permanent ordered mesopores and favorable electronic structure, Pd-supported 3DOm-SnO 2 can efficiently catalyze the unprecedented sequential hydrogenation of 4-nitrophenylacetylene to produce 4-nitrostyrene, then 4-nitroethylbenzene, and finally 4-aminoethylbenzene. DFT calculations further reveal the favorable synergistic effect between Pd and 3DOm-SnO 2 via moderate electron transfer for realizing this sequential hydrogenation reaction. Our work underlines the crucial role of silanol groups in inducing the high-yield heterogeneous crystallization of 3DOm-SnO 2, shedding light on the rational design and construction of various 3DO single crystals that are of great practical significance.