Bandgap engineering of tetragonal phase CuFeS_(2)quantum dots via mixed-valence single-atomic Ag decoration for synergistic Cr(VI)reduction and RhB degradation

摘要

Bandgap engineering through single-atom site binding on semiconducting photocatalyst can boost the intrinsic activity,selectivity,carrier separation,and electron transport.Here,we report a mixed-valence Ag(0)and Ag(I)single atoms co-decorated semiconducting chalcopyrite quantum dots(Ag/CuFeS_(2)QDs)photocatalyst.It demonstrates efficient photocatalytic performances for specific organic dye(rhodamine B,denoted as RhB)as well as inorganic dye(Cr(VI))removal in water under natural sunlight irradiation.The RhB degradation and Cr(VI)removal efficiencies by Ag/CuFeS_(2)QDs were 3.55 and 6.75 times higher than those of the naked CuFeS_(2)QDs at their optimal pH conditions,respectively.Besides,in a mixture of RhB and Cr(VI)solution under neutral condition,the removal ratio has been elevated from 30.2%to 79.4%for Cr(VI),and from 95.2%to 97.3%for RhB degradation by using Ag/CuFeS_(2)QDs after 2 h sunlight illumination.The intrinsic mechanism for the photocatalytic performance improvement is attributed to the narrow bandgap of the single-atomic Ag(I)anchored CuFeS_(2)QDs,which engineers the electronic structure as well as expands the optical light response range.Significantly,the highly active Ag(0)/CuFeS_(2)and Ag(I)/CuFeS_(2)effectively improve the separation efficiency of the carriers,thus enhancing the photocatalytic performances.This work presents a highly efficient single atom/QDs photocatalyst,constructed through bandgap engineering via mixed-valence single noble metal atoms binding on semiconducting QDs.It paves the way for developing high-efficiency single-atom photocatalysts for complex pollutions removal in dyeing wastewater environment.