多孔SiC纳米片的原位合成及光催化性能

In Situ Synthesis and Photocatalytic Properties of Porous SiC Nanosheets

以可膨胀石墨作为原材料,通过高温膨化和机械砂磨得到石墨薄片,再以石墨薄片作为模板合成了不同比表面积的碳化硅纳米片(SiCNSs)。探究了比表面积对SiCNSs光催化制氢性能的影响。结果表明,SiCNSs的比表面积对其产氢性能影响显著,提高光催化剂的比表面积有利于增强其产氢活性。SiCNSs的最大比表面积可达149 m^(2)·g^(-1),其光解水产氢速率为51.0μL·g^(-1)·h^(-1)。在对石墨薄片和SiCNSs结构、形貌分析的基础上,提出了以石墨薄片为模板原位生成SiCNSs的形成机理,该过程主要遵循气固反应机制。高温下,气态的SiO和Si与石墨薄片反应生成SiCNSs,产物较好地继承了石墨薄片的片状结构。大尺寸石墨片上未反应部分除碳之后留下了大量纳米尺寸穿孔,使得所生成SiC的比表面积反而比小尺寸石墨片产物的高。

Using expandable graphite as raw material,graphite flakes were obtained through high-temperature expansion and mechanical sanding.Graphite flakes were used as templates to synthesize silicon carbide nanosheets(SiCNSs)with different specific surface areas.The effect of specific surface area on the photocatalytic hydrogen production performance of SiCNSs was explored.The results show that the specific surface area of SiCNSs has a significant impact on its hydrogen production performance,and increasing the specific surface area of the photocatalyst is beneficial to enhance its hydrogen production activity.The maximum specific surface area of SiCNSs can reach 149 m^(2)·g^(-1),and its photolysis water hydrogen evolution rate was 51.0μL·g^(-1)·h^(-1).Based on the analysis of the structure and morphology of graphite flakes and SiCNSs,the formation mechanism of in situ generation of SiCNSs using graphite flakes as a template is proposed.The process mainly follows the gas-solid reaction mechanism.At high temperatures,gaseous SiO and Si react with graphite flakes to form SiCNSs,and the product better inherits the flake structure of graphite flakes.After removing carbon from the unreacted part of the large-size graphite sheet,a large number of nano-sized perforations were left,so that the specific surface area of the produced silicon carbide was higher than that of the small-size graphite sheet.