Silica-encapsulated gold core@shell nanoparticles (Au@SiO₂ CSNPs) were synthesized via a tunable bottom-up procedure to catalyze the aerobic oxidation of benzyl alcohol. The nanoparticles exhibit a mesoporous shell which enhances selectivity by inhibiting the formation of larger species. Adding potassium carbonate to the reaction increased conversion from 17.3 to 60.4% while decreasing selectivity from 98.4 to 75.0%. A gold nanoparticle control catalyst with a similar gold surface area took 6 times as long to reach the same conversion, achieving only 49.4% selectivity. These results suggest that the pore size distribution within the inert silica shell of Au@SiO₂ CSNPs inhibits the formation of undesired products to facilitate the selective oxidation of benzaldehyde despite a basic environment. A smaller activation energy, mass transport analysis, and mesopore distribution together suggest the Au@SiO₂ CSNP catalyst demonstrates higher activity through beneficial in-pore orientation, promoting a lower activation energy mechanistic pathway. Taken together, this is a promising catalytic structure to optimize oxidation chemistries, without leveraging surface-interacting factors like chelating agents or active support surfaces.

中文翻译：

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介孔二氧化硅包裹的金核-壳纳米粒子，用于无溶剂的活性苄醇氧化

通过可调节的自下而上的程序合成了二氧化硅包裹的金核壳纳米粒子（Au @ SiO ₂ CSNPs），以催化苯甲醇的好氧氧化。纳米颗粒具有介孔壳，该壳通过抑制较大物种的形成而提高了选择性。向反应中添加碳酸钾将转化率从17.3％提高到60.4％，同时将选择性从98.4％降低到75.0％。具有相似金表面积的金纳米颗粒控制催化剂花费了6倍的时间才能达到相同的转化率，仅达到49.4％的选择性。这些结果表明，Au @ SiO ₂惰性二氧化硅壳内的孔径分布尽管存在碱性环境，CSNPs仍可抑制不需要的产物的形成，从而促进苯甲醛的选择性氧化。较小的活化能，传质分析和中孔分布一起表明，Au @ SiO ₂ CSNP催化剂通过有益的孔内取向表现出较高的活性，从而促进了较低的活化能机理。综上所述，这是一种有前景的催化结构，可在不利用诸如螯合剂或活性载体表面之类的表面相互作用因素的情况下优化氧化化学性能。