一种具有温敏表面的氧化石墨烯负载钯催化剂的制备及催化性能

以过硫酸铵（APS）为引发剂，N-异丙基丙烯酰胺（NIPAM）为单体，在氧化石墨烯（GO）表面生长温敏高分子聚（N-异丙基丙烯酰胺）（PNIPAM），获得复合载体GO-PNIPAM，并通过水相浸渍还原法制备具有温度敏感特性的Pd催化剂（Pd/GO-PNIPAM）。采用红外光谱、差示量热、热重、元素分析、透射电镜和电感耦合等离子原子发射光谱对复合载体GO-PNIPAM和Pd催化剂进行表征。结果表明，PNIPAM在GO上的接枝率约占60%。GO-PNIPAM显示出明显的温敏效应，其最低临界溶液温度约37℃。Pd/GO-PNIPAM上Pd纳米颗粒的平均粒径为(4.70±0.85)nm，远小于Pd/GO中Pd平均粒径(8.79±2.68)nm。因此，PNIPAM在GO上的接枝为金属纳米颗粒的沉积提供了大量的锚定位点，有助于金属纳米颗粒在其上的分散。Pd/GO-PNIPAM在高温下（80℃）肉桂醛（CAL）的选择性加氢反应中显示出优良的催化性能，初始转换频率（initial TOF）达192.3min^-1，高于GO负载Pd催化剂（Pd/GO，103.5min^-1）。Pd/GO-PNIPAM较高的Pd纳米颗粒分散性和高温下对CAL良好的吸附性能协同作用，导致其催化活性提高。

Palladium catalyst supported on graphene oxide with temperature-sensitive surface and its catalytic performance

Thermo-sensitive poly(N-isopropylacrylamide) (PNIPAM) was grown on graphene oxide (GO) with ammonium persulfate (APS) as the initiator to prepar the composite GO-PNIPAM, which was further employed to support Pd catalyst (Pd/GO-PNIPAM). The GO-PNIPAM and its supported Pd catalyst were characterized by FTIR, DSC, TG, OEA, TEM and ICP-AES. The results showed that 60% of the PNIPAM had grafted on GO. The GO-PNIPAM exhibited obvious thermoresponsive effect and its lower critical solution temperature (LCST) was about 37℃. The Pd particles deposited on the Pd/GO-PNIPAM had smaller size (4.70nm±0.85nm) than those on Pd/GO (8.79nm±2.68nm) because the graft of PNIPAM on GO provided a great number of anchoring sites for the dispersion of Pd nanoparticles. The Pd/GO-PNIPAM showed excellent catalytic activity in the selective hydrogenation of cinnamaldehyde (CAL) at high temperature (80℃) and the initial TOF was 192.3min^-1, higher than that of Pd/GO (about 103.5min^-1). The good Pd dispersion of Pd/GO-PNIPAM as well as its great adsorption ability to reactants at high temperature jointly resulted in an enhancement to the catalytic activity.