Plasmonic Bi/COF Nanoheterojunctions for Visible-Light Photodegradation of Phenolic Pollutants

Localized surface plasmon resonance (LSPR) is a highlypromisingmethod to enhance the catalytic performance of photocatalysts. Asan earth-abundant metal element, bismuth (Bi) holds a great promiseas an economically feasible substitute for expensive noble metalsto prepare metal/semiconductor composite-based plasmon-enhanced photocatalysts,which urgently need promising semiconductors to couple with Bi. Herein,we demonstrate that covalent organic frameworks (COFs) can be usedas promising candidates to prepare high-performance Bi/COF plasmonicphotocatalysts by providing large numbers of active sites for the in situ growth of non-noble metal Bi, exposing more activesites, and overcoming the problems of low active oxygen utilizationand blocked charge transfer. As-prepared Bi/COF nanoheterojunctionsnot only show increased visible light harvesting, accelerated electrontransfer, and retarded charge recombination but also well maintainthe strong substrate adsorption capability of COFs, making the photocatalyticreactions work in an adsorption-assisted manner. Via a plasmon-sensitizedhot electron injection-based photocatalytic mechanism, the proposedBi/COF photocatalyst works well in the visible-light photocatalyticdegradation of organic pollutants with complete photodegradation of4-chlorophenol (4-CP) within 70 min. This work not only provides anon-noble metal Bi-based plasmonic photocatalyst with excellent catalyticperformance but also paves a promising way to construct adsorption-assistedphotocatalytic systems by using COFs.

Automated summary

This research demonstrates that covalent organic frameworks (COFs) can be used as promising candidates to prepare high-performance Bi/COF plasmonic photocatalysts. The prepared Bi/COF nanoheterojunctions not only show increased visible light harvesting, accelerated electron transfer, and retarded charge recombination but also maintain strong substrate adsorption capability of COFs. Moreover, the proposed Bi/COF photocatalyst works well in the visible-light photocatalytic degradation of organic pollutants.