多孔g-C₃N₄负载不同受限贵金属纳米粒子及其催化活性研究

Different Confined Noble-Metal Nanoparticles Catalysts on Porous g-C₃N₄ and Enhanced Catalytic Activity

通过简单的光化学还原方法,得到一系列具有相同负载量的贵金属(Au, Ag, Pd, Pt)纳米颗粒@多孔g-C3N4纳米复合材料。利用XRD、SEM、TEM、XPS、FT-IR和N2物理吸附等手段对样品的微观结构、形貌等性能进行了表征,并评价了M@pg-C3N4纳米复合材料对KBH4还原4-硝基苯酚(4-NP)的催化活性。其结果表明,贵金属纳米颗粒均匀负载在pg-C3N4上,与纯pg-C3N4相比,所有M@pg-C3N4纳米复合材料对4-NP催化还原性能明显增强。其中,Au@pg-C3N4的最高速率常数达到1.386 min−1,优于M@pg-C3N4的催化活性(M = Ag,Pd和Pt)。这归因于g-C3N4的多孔结构对不同贵金属纳米颗粒的整体限域效应和贵金属纳米粒子的优良的电子传输性能。本文为贵金属基复合催化剂的选择和应用提供了一定的实验依据。

Noble-metal nanoparticles (Au, Ag, Pd, Pt) with the same nominal loading amounts were immobi-lized on porous g-C3N4 (pg-C3N4) using a facile photochemical reduction route. The as-prepared M@pg-C3N4 (M = Au, Ag, Pd, Pt) nanocomposites were characterized by XRD, SEM, TEM, XPS, FT-IR and N2 physisorption measurements. The results indicated that the noble-metal nanoparticles were successfully grown on the pg-C3N4. The catalytic activities of the M@pg-C3N4 composites to the reduction of 4-nitrophenol (4-NP) with KBH4 were tracked by UV-visible spectroscopy. It was found that the M@pg-C3N4 nanocomposites exhibited enhanced catalytic performance toward the reduction of 4-NP. In particular, the highest rate constant reaches 1.386 min−1 in the dark over the Au@pg-C3N4, which exceed the catalytic activity of M@pg-C3N4 (M = Ag, Pd and Pt). It attributed to the integrative confining effect of porous structure of g-C3N4 and the super electron conductive properties of noble-metal nanoparticles.