Carbon dot-based artificial light-harvesting systems with sequential energy transfer and white light emission for photocatalysis

In this work, we designed and synthesized cationic carbon dots(CDs) with a size distribution of 1.6–3.7 nm, which exhibited dark blue fluorescence in the aqueous solution. Based on its excellent luminescence properties, we used it as an energy donor to construct a sequential artificial light-harvesting system(LHS) by employing the energy-matching dyes eosin Y disodium salt(EY) and sulforhodamine101(SR101), which could regulate the white light emission(Commission Internationale de l'Eclairage(CIE) coordinate:(0.30, 0.31)) with the energy transfer efficiency(ΦET) of 53.9% and 20.0%. Moreover, a single-step artificial LHS with white light emission(0.32, 0.28) can be constructed directly using CDs and dye solvent 43(SR) with ΦETand antenna effect(AE) of 48.8% and 6.5, respectively. More importantly,CDs-based artificial LHSs were firstly used in photocatalytic of α-bromoacetophenone, with a yield of90%. This work not only provides a new strategy for constructing CDs-based LHSs, but also opens up a new application for further applying the energy harvested in CDs-based LHSs to the field of the aqueous solution photocatalysis.

Construction and application of the polyelectrolyte-based sequential artificial light-harvesting system

In this work,we have designed and synthesized a cyano-substituted p-phenylenevinylene derivative(PPTA),which can self-assemble into positively charged nanoparticles in an aqueous solution with a deep green fluorescence.An anionic polyelectrolyte material guar gum modified by carboxylic acid(GP5A)was chosen to build an artificial light-harvesting system(LHS)through self-assembly with PPTA,in which two acceptors Eosin Y(EY)and Nile red(NiR)were loaded into the PPTA-GP5A assemblies through electrostatic interaction and Van der Waals force.By adjusting the molar ratio of PPTA-GP5A/EY at 1:0.004,the one-step artificial LHS can exhibit high energy transfer efficiency(Φ_(ET))(38.9%)and antenna effect(AE)(4.6).Subsequently,with the addition of NiR,theΦET and AE of the two-step sequential artificial LHS were calculated to be 71.9%and 13.5,respectively.Moreover,the two-step artificial LHS constructed by the polyelectrolyte material GP5A can be used as a nanoreactor to photocatalyst alkylation of C-H bonds of phenyl vinyl sulfone(PVS)and tetrahydrofuran(THF)in water with a yield of 42%.Therefore,we have constructed an artificial LHS with two-step energy transfer based on polyelectrolytes through the electrostatic interaction to improve energy transfer efficiency,which can also be used as a nanoreactor for photocatalysis.