We describe the synthesis of even-dispersed palladium nanoparticles (Pd NPs) confined within a cellulose nanofiber (CNF) matrix for developing a high-performance and recyclable catalyst. The CNF matrix was composed of CNF-assembled mesoporous nanosheets and appeared as soft and hydrophilic foam. Ultrafine Pd NPs (∼6 nm) with high-loading (9.6 wt%) were in situ grown on these mesoporous nanosheets, and their dense spatial distributions were likely to generate nano-confinement catalytic effects on the reactants. Consequently, the CNF-confined Pd NPs (CNF-Pd) exhibited an enhanced room-temperature catalytic activity on the model reaction of 4-nitrophenol hydrogenation with a highest rate constant of 8.8×10⁻³ s⁻¹ and turnover frequency of 2640 h The CNF Pd catalyst possessed good chemical stability and recyclability in aqueous media which could be reused for at least six cycles without losing activity. Moreover, chemoselective reduction of 3 nitrostyrene was achieved with high yield (80%–98%) of 3-aminostyrene in alcohol/water cosolvent. Overall, this work demonstrates a positive nanoconfinement effect of CNFs for developing stable and recyclable metal NP catalysts.

我们描述了限制在纤维素纳米纤维（CNF）基质内的均匀分散钯纳米颗粒（Pd NPs）的合成，以开发高性能和可回收的催化剂。CNF基质由CNF组装的中孔纳米片组成，表现为柔软的亲水性泡沫。具有高载量（9.6 wt％）的超细Pd NP（〜6 nm）原位生长在这些介孔纳米片上，其密集的空间分布可能对反应物产生纳米约束催化作用。因此，CNF限制的Pd NPs（CNF-Pd）在4-硝基苯酚加氢的模型反应中表现出增强的室温催化活性，最高速率常数为8.8×10 ^-3 s ^-1CNF Pd催化剂的周转频率为2640 h，在水性介质中具有良好的化学稳定性和可循环性，可以重复使用至少六个循环而不会失去活性。此外，在乙醇/水助溶剂中3-氨基苯乙烯的高收率（80％–98％）可实现3硝基苯乙烯的化学选择性还原。总体而言，这项工作证明了CNF对开发稳定且可回收的金属NP催化剂具有积极的纳米限制作用。