高硅生物质（稻壳）热化学过程中硅酸盐自模板催化类石墨烯碳的原位生长及其机理研究

This project is inspired by a special phenomenon that graphene-like carbon can be prepared by the pyrolysis-activation annealing of rice husk without any external catalytic template. From this, we raised a hypothesis that the silicate skeleton generated during annealing of high silica biomass can worked as the catalysis to induce the growth of graphene. Thereout, we propose a strategy to integrate the natural carbon source and self-generated silicate catalytic template to in-situ grow graphene. This method is able to integrate several advantages of this self-generated silicate template: catalytic effect, structural control effect as well as easy-to-remove merit. Accordingly, it is expected to develop a cheap, simple and green fabricating route to produce graphene-like carbon. Due to seldom previous work has been reported on it, we intend to systematically study the catalytic mechanism of the biomass generated silicate template. Via the process of exploring the technique, we would expected to:1) find out the influence of the silicate template morphology on the catalytic effect and the properties of grown graphene; 2) clarify interactions between the silicate template and the intermediate products during annealing; 3) finally summarize the thermodynamic and kinetic laws for the growth of graphene. Hence, the project is expected to reveal the catalytic mechanism of non-metal template in biomass system. It can also help promote an effective model of producing graphene-like carbon from high-silica biomass which has a great academic value. Illuminated by above, we are able to develop a simple and green synthesis route to transform the high-silica biomass waste to high-performance carbon which has a considerable application significance.

本项目从稻壳热解-活化处理时形成少层石墨烯的特殊现象出发，提出高硅生物质原料在热处理过程中形成的自体硅酸盐骨架诱导生长石墨烯的猜想。并由此提出一种利用碳源与催化剂一体化原位生长类石墨烯碳的新思路。该方法借助硅酸盐自模板的原位催化、结构调控、易去除等多重优势，可望开发一种廉价简单、绿色可控的工艺路线。基于目前类似体系催化机理研究的空白，项目拟系统的探讨硅酸盐作为模板生长石墨烯片层的规律与机制。通过优化工艺条件与模拟实验，深入研究硅酸盐骨架的形貌对形成的石墨烯片层结构的影响，明确热处理过程中间产物与硅酸盐模板的相互作用，并总结出该条件下石墨烯生长的热力学与动力学规律。本项目的研究可望明确非金属模板在生物质原料体系中生长石墨烯的的催化机理，以及高硅生物废料生长类石墨烯碳的模式与调控机制，具有重要学术价值。对这些规律的认识可指导开发将高硅农废转变为高性能碳材料的简单绿色合成路线，具有重要现实意义。

稻壳不仅具有传统生物质材料所含有的丰富的纤维素、半纤维素和木质素等有机成分，其结构中还包含大量的硅氧键。因此，稻壳与传统生物质材料相比具有显著的特异性。为了更好的利用稻壳的这种特殊生物质材料，本项目从四个方面全面剖析了稻壳中有机成分的热解行为和无机成分模板催化机制及形成类石墨烯结构的电化学应用前景。.具体研究内容包括四部分：1，鉴于稻壳中硅氧无机结构有助于类石墨烯材料的形成，项目设计研究了氯化锌/稻壳共热解过程，结果表明中间体中存在丰富的硅酸锌，且热解碳材料具有典型的类石墨烯特性；2，为探究稻壳热解气与硅酸盐模板形成类石墨烯的适宜条件，进一步设计了稻壳热解气与硅酸盐高温相互作用的实验。以稻壳热解气体为碳源，硅酸盐材料为催化载体，结果表明，稻壳热解气能够在硅酸盐表面形成类石墨烯结构。并且稻壳基硅酸盐模板具有更为优异的结构调控能力，以稻壳为前驱体制备的硅酸盐具有更好的诱导热解气形成类石墨烯材料的效果；3，原位热重-红外联用技术对稻壳分解行为的研究阐释了硅酸盐模板具有催化芳香烃重组构建类石墨烯的功能。稻壳热解与其内部有机成分有较大关系，热解过程分多步进行。低温区木质素中支链芳香烃结构先行断裂释放；中温区纤维素、半纤维素大量分解产生脂肪烃、高温区木质素中多环芳烃进一步断裂成小分子芳香烃释放；4，项目以稻壳为前驱体，利用不同金属离子与稻壳中硅氧键的结合形成的硅酸盐模板的催化特性，可以获得比表面积超过2000m2/g的多孔类石墨烯材料。这些类石墨烯材料可以用作锂离子电池负极，能搞提供1000mAh/g的比容量。.稻壳中木质素、纤维素和半纤维素的多步骤热解行为可望为稻壳基类石墨烯材料的精细调控和类石墨烯材料品质的提升提供有效助力。可通过对稻壳的进一步研究，开发具有特异应用领域的石墨烯材料。本项目的开展进一步明晰了类石墨烯材料可以通过廉价生物质作为前驱体制备而成，对生物废料高附加值开发具有显著的学术价值和现实意义。