模板法-脱合金制备低密度、分级多孔金及其电催化性能

Templating-dealloying synthesis and electrocatalytic properties of the low-density gold with hierarchical pore structure

摘要:

本文提出了以模板法-脱合金复合方法制备低密度分级多孔金。在该方法中，以直径为700 nm的二氧化（SiO2）微球作为模板，通过化学镀的方法依次制备了Ag@SiO2和Au@ Ag@ SiO2核壳粒子，并通过冷压-烧结方法制备了Au@ Ag@ SiO2合金块材。通过连续改变腐蚀溶液，SiO2模板以及Ag元素从Au@ Ag@ SiO2合金中完全去除。将SiO2从Au@ Ag@ SiO2微球完全去除从而得到了大尺寸空心球壳（直径约为675 nm），将Ag元素脱合金去除从而在球壳表面形成了许多小尺寸的孔结构（直径约为75nm）。TEM图像表明，块状金样品中的韧带由具有多晶特性的纳米晶粒组成。这种具有低密度1.1 g/cm3（相对密度为5.7%）和高表面积4.24 m2/g的分级纳米多孔金材料在碱性溶液中对甲醇电氧化具有优良的催化活性以及快速的传质速率，表明其在催化领域具有广阔的应用前景。

Abstract:

The composite technique of templating and dealloying is proposed for synthesizing the low-density and hierarchical nanoporous gold (NPG). In this technique, the silica (SiO2) microspheres with an average diameter of ~700 nm are prepared as the sacrificial templates, the Ag@SiO2 and Au@Ag@SiO2 core-shell microspheres are prepared successively via the electroless plating approach, and the Au@Ag@SiO2 alloy bulks are formed through the cold-pressing and sintering method. By continually changing corrosion solutions, the templates and the Ag element can be completely eliminated from the Au@Ag@SiO2 alloy. The SiO2 templates are completely removed from Au@Ag@SiO2 microspheres so as to form the large-sized hollow spherical shells (with the diameter of ~675 nm), and the Ag element are eliminated by dealloying so as to generate a lot of small-sized pore (with the diameter of ~75 nm) structures on the shells. TEM images illustrate that the ligaments in NPG consist of the nano-grains with polycrystalline characteristic. The hierarchical NPG foam with low-density of 1.1 g/cm3 (the relative density of ~5.7 %) and high surface area of 4.24 m2/g shows the excellent catalytic activity and the rapid mass transfer rate for methanol electro-oxidation in alkali solution, which implies a promising application in catalysis.