【摘要】 以K₃[Co（CN）₆]为Co源，硫脲为S源，富含-OH和-NH₂的天然亲水性高分子壳聚糖为碳源，通过形成CS-K₃[Co（CN）₆]水凝胶将Co前驱体和S源均匀分布于C前驱体中。水凝胶形成的主要驱动力来自金属Co离子与壳聚糖中-NH₂的配位交联以及Co离子之间通过-CN的桥接作用。得益于均匀分散的前驱体和后续热解处理初期形成的Co的催化作用，通过简单地调控Co与S的原子比，原位构建出均匀镶嵌有Co/Co₉S₈异质结的N,S共掺杂富含微孔的碳纳米片（Co/Co₉S₈@N,S-CNSs）。采用SEM、TEM、BET、XRD、Raman、XPS和电化学工作站等方法对所制备催化剂的形貌、组成和结构以及电催化性能进行了表征。结果表明，形成的Mott-Schottky型Co/Co₉S₈异质界面有效地调控了活性中心的电子结构和电荷传输特性；二维掺杂多孔碳纳米片的负载使活性位点更加均匀分散，同时提供了高速的电子和传质通道，也避免了活性位点在催化过程中的迁移聚集。两者的协同作用使合成的Co/Co₉S₈@N,S-CNSs复合催化剂具有了更优的催化性能，在10 mA·cm^-2的电流密度下，其催化碱性析氧反应/OER的过电位仅为304 mV,优于商业化的RuO₂催化剂。该研究为发展具有优异电催化性能的廉价过渡金属催化剂提供帮助。更多还原

【Abstract】 Using K₃[Co（CN）₆] as Co source, thiurea as S source and natural hydrophilic polymer chitosan rich in-OH and-NH₂ as carbon source, the Co precursor and S source were uniformly distributed in the C precursor by forming CS-K₃[Co（CN）₆] hydrogel. The main driving force of hydrogel formation is the coordination crosslinking of metal Co ions with-NH₂ in chitosan and the bridging between Co ions via-CN. Thanks to the uniformly dispersed precursor and the catalysis of the Co formed at the initial stage of subsequent pyrolysis, N, S co-doped carbon nanosheets with encaged Co/Co₉S₈ heterojunction（Co/Co₉S₈@N, S-CNSs） were constructed in situ by simply regulating the atomic ratio of Co to S. The morphology, composition and structure of the prepared electrocatalysts and the oxygen evolution reaction performance were analyzed with SEM, TEM, BET, XRD, Raman, XPS and electrochemical workstations. The results show that the Mott-Schottky type Co/Co₉S₈ interface effectively regulates the electronic structure and charge-transport characteristics of the active center. The loading of two-dimensional doped porous carbon nanosheets makes the active sites more evenly dispersed, while providing high-speed electron and mass transfer channels, as well as avoiding the migration and aggregation of active sites during the catalytic process. The synergistic action of these two allows the proposed Co/Co₉S₈@N, S-CNSs catalyst have better electrocatalytic performances. At a current density of 10 mA·cm^-2, the overpotential of the proposed catalyst for basic oxygen evolution reaction/OER is only 304 mV, which is better than that of the commercial RuO₂. This study is helpful for the development of cheap transition metal catalysts with excellent electrocatalytic properties.更多还原