木质活性炭微结构调控及其催化氧还原反应构效关系研究

Activated carbon materials catalyze the oxygen reduction reaction (ORR) to improve the efficiency of energy conversion, power density of metal air battery and fuel cells. There are some problems, such as the low control on microstructure, and the low construction efficiency of catalytic active sites, which raise the overpotential and reduce the utility of batteries. Focusing on the above questions, fast growing hard wood (paulownia wood/paper mulberry wood) will be conducted on depolymerization reaction at low temperature with different catalysts in this project. The effect rules of catalysts on reaction mechanism of wood fiber, morphology, pore structure and formation process of activated carbon will be investigated to improve the controllability of microstructure. Catalytic active sites of activated carbon will be constructed via the composite modification with Co and N doping. The influence of modification conditions on the states of Co and N, and components of activated carbon will be studied. The regulation mechanism of modification will be revealed for precise preparation of highly active carbon catalysts. Based on the ORR performances, oxygen adsorption performances via in situ Raman spectroscopy and transitional state energy of reactive species via the DFT simulations, the catalysis mechanism and structure-activity relationship will be explained. This project will establish the effective ways to improve the building efficiency of catalytic active center. This project will offer new thoughts for the exploration of highly effective and industrial scale preparation of ORR catalysts, and promote high-valued utility of forest biomass.

活性炭催化氧还原反应 (ORR) 可提升金属空气电池和燃料电池的能量转换效率、功率密度。现阶段活性炭微结构可控性低，催化活性中心构建效率低，造成ORR过电位高、电池利用效率低。针对上述问题，本项目研究速生阔叶材 (泡桐木/构木) 低温解聚过程中不同催化剂对木质纤维的反应机制和对活性炭形貌、孔结构影响规律，解析低温解聚对活性炭形成过程作用机制，提高活性炭微结构可控性；并通过复合改性构建催化活性中心，研究改性条件对钴、氮存在状态及活性炭微观组分影响，揭示复合改性对催化活性中心调控机制，精准制备高活性催化剂；系统研究活性炭催化ORR性能，采用原位拉曼光谱研究活性炭吸附氧分子性能，结合DFT模拟计算催化ORR过程中各过渡态能量，解析活性炭催化机理和催化ORR构效关系，确立提高催化活性中心构建效率的有效途径。本项目将为开发高效、可规模制备的ORR催化剂提供新方法，促进林木生物质的高值化利用。

基于林产化学工业领域高端储能活性炭发展需求和国家新能源发展战略，针对当前活性炭氧还原反应（ORR）催化剂制备过程中存在的微结构可控性差、催化活性位点构建效率低的关键问题，创新水热催化芳香化交联、界面组装、无机盐催化热解等方法提高活性炭微结构可控性，探明了杂原子和缺陷结构、金属杂原子复合改性等调控活性中心的作用机理，创制出一系列高性能催化ORR活性炭材料。为设计开发高端活性炭催化剂提供理论支持，对林木资源高值化利用和新能源产业发展具有重要意义。取得如下创新成果：.（1）创新进行水热催化下低温解聚、碳化活化同步热解、杂原子-缺陷复合改性等步骤创制出类石墨烯形貌活性炭空气电极。以不同类型林木生物质制备出类石墨烯活性炭催化剂，阐明了水热过程木质纤维芳香化交联、界面组装形成片层炭结构机理，发现了热解过程中熔融无机盐促使石墨微晶组合、生长形成类石墨烯形貌片层碳的机制，揭示了炭表面多类型缺陷和杂原子改性协同调控催化活性的作用机制，研发出富缺陷、类石墨烯形貌生物基炭材料的普适性制备方法，催化ORR半波电位达到0.84 V。.（2）研究出活性炭催化剂碳骨架化学环境调控方法，揭示了金属和杂原子复合改性调控ORR活性中心机制。以泡桐木/构树木为原料，采用多种方法对活性炭碳骨架进行化学环境调控，创制钴/铁金属与氮、氧、磷等复合改性的活性炭催化剂，阐明了金属杂原子复合改性调控碳骨架形成不饱和配位环境提升催化活性的机制，催化ORR半波电位达到0.86 V，组装的锌空电池峰值功率密度达到155 mWcm-2。.（3）利用DFT理论解析活性炭催化活性提升机理。揭示了泡桐木P-CoO@PWC活性炭表面磷原子诱导促进催化活性提升的新机制；阐明了FeP-NBC活性炭中活化水和活化氧双活化策略新设计方法的有效性。DFT理论计算结果有利于活性炭催化剂理性设计。