Construction of carbon nitride-based heterojunction as photocatalyst for peroxymonosulfate activation: Important role of carbon dots in enhancing photocatalytic activity
Pei Yang, An Shen, Ziqi Zhu, Ling Wang, Ruixin Tang, Kai Yang, Minzhi Chen, Hongqi Dai, Xiaoyan Zhou
Abstract
Strategic combination of carbon dots (CDs) and carbon nitride (CN) has provided an appealing strategy to synthesize metal-free carbonaceous catalyst for environmental-concerned photocatalytic applications. However, there still exists an ambiguous cognition on the relationship between functional structures of CDs and enhanced photocatalytic activity of CDs/CN composites. Herein, different types of functionalized CDs were physically integrated with CN matrix to construct CDs/CN heterojunctions. By systematically investigating the efficiency of CDs/CN-catalyzed peroxymonosulfate (PMS) in p -nitrophenol degradation, we revealed that the CDs enriched with carboxyl groups or doped by pyrrolic-N inclined to attract photogenerated electrons from CN host, and thus contributed to the photocarriers separation. As such, these CDs-imparted active sites can dramatically facilitate PMS activation, and further p -nitrophenol degradation by photogenerated holes and multiple reactive oxygen radicals. Nonetheless, the CDs mainly doped by electron-donating graphitic-N could form electron-rich regions at the interface of CN host upon forming heterojunction, thus making barriers against charge separation in the PMS-mediated oxidation process. Taken together, this study will shed light on the rational design of CDs/CN heterojunctions with high photocatalytic activity.