Boosting photocatalytic activity through in-situ phase transformation of bismuth-based compounds on carbon dots and quantification analysis of intrinsically reactive species in photocatalysis

Abstract

As a photocatalyst, both BiOCOOH and (BiO)2CO3 are only active under UV light irradiation. In this contribution, a room-temperature approach is firstly demonstrated to develop in situ incorporation of green carbon dots (CDs) into BiOCOOH (CDs@BiOCOOH) by taking advantage of the residual HCOOH for preparing CDs. As-prepared CDs@BiOCOOH is endowed with broad visible light absorption. By the reaction with NaBH4, BiOCOOH is subsequently transformed into (BiO)2CO3 at room temperature, forming a new heterostructure of CDs@(BiO)2CO3. Not only does this heterostructure display exceptionally stronger visible light harvesting capability than CDs@BiOCOOH due to the introduction of more structural defects in the process of phase transformation, but it also possesses more superior degradation ability for the organic pollutants under visible light. Its photocatalytic activity is raised to over 7 times comparing to BiOCOOH. Accordingly, a facile and room-temperature synthesis strategy is presented for large-scale production of CDs@(BiO)2CO3 with highly efficient use of sunlight. To understand photocatalytic mechanism, we offer a unique technique for the quantification and the kinetics evaluation of the intrinsic reactive species produced in photocatalysis as well.