活性物种钴周围化学环境对钴@碳基电催化剂析氢析氧活性的影响

Effect of chemical environment around active species cobalt on the hydrogenand oxygen precipitation activity of cobalt@carbon based electrocatalysts

控制活性物种周围化学环境是提高催化反应进行的一种有效调控策略.以多孔碳为基体,通过引入N原子并改变煅烧气氛,采用一步熔盐法合成了包含不同钴物种的Co@C基电催化剂.结果表明,在氩气气氛下煅烧仅生成金属Co,而在空气气氛下同时生成金属Co和CoO,N原子的引入可以调控钴物种的化学环境和分散性.对Co@C基电催化剂活性分析,发现样品Co/CoO@N-C在碱性条件下同时具有最好的析氢析氧活性.主要原因是N原子的引入对金属Co在碱性析氢反应中起重要作用,而CoO在析氧反应中起决定性作用.同时测试其全解水性能,仅在1.83 V就达到10 mA·cm^(-2)的电流密度.由此可见,调控活性位点周围化学环境对设计高效双功能催化剂具有重要的意义.

Controlling the chemical environment around active species is an effective regulatory strategy to improve the progress of catalytic reactions.Using porous carbon as a matrix,Co@C-based electrocatalysts containing different cobalt species were synthesized by a one-step molten salt method under the conditions of introducing nitrogen atoms and changing the calcination atmosphere.The results show that only metallic Co is formed by calcination in argon atmosphere,while metallic Co and CoO are simultaneously formed in air atmosphere,and the introduction of nitrogen atoms can control the chemical environment and dispersion of cobalt species.The activity analysis of Co@C-based electrocatalyst shows that the sample Co/CoO@N-C has the best hydrogen evolution and oxygen evolution activity under alkaline conditions.The main reason is that the introduction of nitrogen atoms plays an important role in metallic Co in the alkaline hydrogen evolution reaction,while CoO plays a decisive role in the oxygen evolution reaction.At the same time,the overall water splitting performance was tested,and a current density of 10 mA·cm^(-2) was achieved at only 1.83 V.It can be seen that the regulation of the chemical environment around the active site is of great significance for the design of efficient bifunctional catalysts.