Ouyang Huijun, Fang Chenhong, Xu Zhi, Li Le, Xiao Guyu
Shanghai Key Laboratory of Electrical Insulation and Thermal Ageing, School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China.
Nanoscale. 2022 Aug 11;14(31):11298-11304. doi: 10.1039/d2nr01655a.
Porous carbons prepared using a self-template approach inherit the pore features of template, but they exhibit almost no evenly dispersed mesopores, which is significant for diffusion-limited applications. Herein, N-doped hierarchically porous carbons (NHPCs) with uniform mesopores are prepared using a self-template method. The spherical single-molecule micelle of polystyrene--poly(4-vinyl pyridine) (PS--P4VP) is turned into a Zn-coordinated PS--P4VP micelle (CPM) by coordination of Zn with the P4VP shell. Then, the self-template of the CPM is carbonized into a hollow carbon nanosphere. During carbonization, the PS core is decomposed to generate the central mesopore, whereas the Zn-coordinated P4VP shell is transformed into a carbonaceous shell. These even hollow carbon nanospheres aggregate to form uniformly mesoporous carbon lumps. Simultaneously, the coordinated Zn of the CPM is reduced to metal zinc at high temperatures and then it is evaporated, thus creating numerous micropores in the carbonaceous shell. These NHPCs with uniform mesopores display a high specific surface area. As a demonstration in diffusion-limited applications, their catalytic performances for the oxygen reduction reaction (ORR) are investigated. Strikingly, NHPCs exhibit outstanding catalytic performances for the ORR. This self-template method paves a facile approach for preparing mesoporous carbons with high performances.
采用自模板法制备的多孔碳继承了模板的孔结构特征，但几乎没有均匀分散的中孔，而这对于受扩散限制的应用来说至关重要。在此，使用自模板法制备了具有均匀中孔的氮掺杂分级多孔碳（NHPCs）。通过锌与聚4-乙烯基吡啶（P4VP）壳层的配位作用，将聚苯乙烯-聚（4-乙烯基吡啶）（PS-P4VP）的球形单分子胶束转变为锌配位的PS-P4VP胶束（CPM）。然后，将CPM的自模板碳化成为中空碳纳米球。在碳化过程中，PS核分解产生中心中孔，而锌配位的P4VP壳层转变为含碳壳层。这些均匀的中空碳纳米球聚集形成均匀中孔的碳块。同时，CPM中配位的锌在高温下还原为金属锌，随后蒸发，从而在含碳壳层中产生大量微孔。这些具有均匀中孔的NHPCs具有高比表面积。作为受扩散限制应用的一个实例，研究了它们对氧还原反应（ORR）的催化性能。令人惊讶的是，NHPCs对ORR表现出优异的催化性能。这种自模板法为制备高性能中孔碳铺平了一条简便的途径。
