氢气热处理活性炭表面模板法生长立方多孔银

Morphosynthesis of Porous Silver Cubes on the Surface of Hydrogen-pretreated Monolithic Activated Carbon

通过氢气高温处理调控成型活性炭(MAC)的表面官能团及孔结构,然后先后吸附Cl^-和Ag^+,以形成的立方AgCl作为牺牲模板,经MAC表面官能团还原制备出立方多孔银.用扫描电子显微镜(SEM)和X射线衍射(XRD)表征了产物的形貌和相结构,并用X射线光电子能谱(XPS)分析了成型活性炭不同处理阶段的表面官能团.研究了制备过程中氢气处理温度、Cl^-预吸附液的浓度、Ag^+浓度及Ag^+前驱体种类等对MAC表面生长银形貌的影响.结果表明,氢气预处理一方面可降低MAC表面含氧官能团的数量,调控MAC还原能力;另一方面可提高MAC比表面积,有利于Cl^-的吸附及AgCl模板的形核.通过氢气预处理,在合适的Cl^-,Ag^+浓度及Ag^+前驱体条件下,可在成型活性炭表面获得外形规整的立方多孔银.

The surface functional groups and pore structures of monolithic activated carbon（ MAC） were modified by thermal treatment under hydrogen atmosphere. Then the hydrogen-treated MAC adsorbed Cl^-and Ag~＋successively,and the as-formed AgCl cubes acted as sacrificial templates,which were in turn reduced by the surface functional groups of MAC,and porous silver cubes were obtained on the surface of MAC through morphosynthetic mechanism. The morphology,phase structure of the products were characterized by scanning electron microscopy（ SEM）,X-ray diffraction（ XRD）,respectively. The functional groups of MAC were analyzed using X-ray photoelectron spectroscopy（ XPS）. The effect of the main experimental conditions on the morphology of silver particles on MAC was investigated,including the temperature of hydrogen treatment,the concentration of Cl^-soaking solutions,the concentration of Ag~＋solutions,and the types of Ag~＋precursor. The results indicated that hydrogen treatment can on one hand reduce the amount of oxygen-containing groups of MAC and tune its reducing ability,and on the other hand improve the specific area of MAC,which may facilitate the adsorption of Cl^-and nucleation of AgCl. With hydrogen treatment,accompanied by proper concentrations of Cl^-and Ag~＋,and proper type of Ag~＋precursor,well defined porous silver cubes can be obtained on MAC.