Nanosheet Array-Like Palladium-Catalysts Pdx/rGO@CoAl-LDH via Lattice Atomic-Confined in Situ Reduction for Highly Efficient Heck Coupling Reaction.
Nanosheet Array-Like Palladium-Catalysts Pdx/rGO@CoAl-LDH via Lattice Atomic-Confined in Situ Reduction for Highly Efficient Heck Coupling Reaction.
复制标题
DOI：
10.1021/acsami.7b11695
复制
发表时间：
2017-10
影响因子：
9.5
通讯作者：
Yanna Wang;Liguang Dou;Hui Zhang
中科院分区：
文献类型：
--
作者：
Yanna Wang;Liguang Dou;Hui Zhang
一系列新型纳米片阵列催化剂Pdx/rGO@CoAl-LDH（x = 0.0098-1.9，是指ICP上以wt %计的Pd负载量，rGO：还原的氧化石墨烯，LDH：层状双氢氧化物）首先通过简单的和绿色晶格原子限制的原位还原氧化性Pd前体，通过纳米杂化rGO@CoAl-的LDH层上的均匀原子分散的还原性Co2+位点来制备。采用柠檬酸辅助水相共沉淀法制备了六方LDH纳米片（约73 × 7 nm），其两侧垂直于rGO层的表面相互交叉。所得的Pd催化剂具有清洁的Pd纳米团簇（NC）与可调的尺寸在1.3-1.8 nm的不同的Pd负载。所有Pdx/rGO@CoAl-LDH催化剂均表现出优异的Heck反应活性，其中Pd纳米颗粒尺寸为1.3 ± 0.2 nm的Pd0.0098/rGO@CoAl-LDH催化剂在非均相催化剂上的最大转化频率为160000 h-1。这些优异的催化活性主要归功于超小尺寸Pd纳米粒子的高分散性和清洁的Pd表面，增加的电子转移容量和比表面积，以及Pd-CoAl-LDH-rGO三相协同效应。此外，催化剂Pd 0.33/rGO@CoAl-LDH显示出广泛的底物适用性，并且可以重复使用超过五次而没有明显的活性损失，从而使本发明的催化剂具有长期稳定性。这些发现使得通过简单和可扩展的合成路线制备的rGO@CoAl-LDH杂化物成为通用的绿色平台，以通过晶格原子限制的原位还原策略来支持其他贵金属或非贵金属NC，以构建更期望的非均相催化剂。
A series of novel nanosheet array-like catalysts Pdx/rGO@CoAl-LDH (x = 0.0098-1.9, refers to Pd loading in wt % on ICP, rGO: reduced graphene oxide, LDH: layered double hydroxide) were first prepared via a simple and green lattice atomic-confined in situ reduction of oxidative Pd precursors by the evenly atomic-dispersed reductive Co2+ sites on LDH layers of a nanohybrid rGO@CoAl-LDH with hexagonal LDH nanoplates (∼73 × 7 nm) interdigitated vertical to the surfaces of rGO layer in both sides, fabricated through a simple citric acid-assisted aqueous-phase coprecipitation method. The as-obtained Pd catalysts possess clean Pd nanoclusters (NCs) with tunable sizes in 1.3-1.8 nm on varied Pd loadings. All the Pdx/rGO@CoAl-LDH catalysts show excellent activities for the Heck reaction, and the Pd0.0098/rGO@CoAl-LDH with the ultrafine Pd NCs of 1.3 ± 0.2 nm yields a maximum turnover frequency of 160 000 h-1 over a heterogeneous catalyst so far. The excellent activities can be attributed to the ultrasmall Pd NCs with high dispersion and clean Pd surfaces, increased electron transfer capacity and surface area, and remarkable Pd-CoAl-LDH-rGO three-phase synergistic effect of the present unique nanosheet array-like Pd NCs catalysts. Moreover, the catalyst Pd0.33/rGO@CoAl-LDH shows a broad range of substrate applicability and can be reused more than five runs without obvious loss of activity, giving the present catalysts long-term stability. These findings make the rGO@CoAl-LDH hybrid prepared by a facile and scalable synthesis route a universal green platform to support other noble or nonprecious metal NCs via lattice atomic-confined in situ reduction strategy to construct more desired heterogeneous catalysts.