Exploring electrochemically prepared carbon dot post-treatments with amphiphilic and nonamphiphilic surfactants

Abstract

Carbon dots (CDs) are versatile, easy to fabricate, chemically stable, and ecofriendly materials. This work presents the impact of different post-treatments, such as centrifugation and filtration, on the photoluminescence (PL) and particle-size distribution of electrochemically synthesized CDs. Because organic envelope surfactants have been reported to influence PL, bare CDs were compared with CDs modified with amphiphilic and nonamphiphilic surfactants. The CD colloidal solution exhibited stabilization in the case of bare CDs and CDs modified with amphiphilic sodium dodecyl sulphate or non-amphiphilic surfactant sodium citrate, as indicated by the zeta potential. The experimental results also revealed a minor influence of the organic envelope on the absorbance or PL spectrum, whereas filtration of the colloid solution had a significant impact, revealing an effect not previously observed. The change in the absorbance spectrum was attributed to sp³ hybridization due to increased disorder and surface states during the filtration process. Absorbance deconvolution also disclosed two energy substates not mentioned elsewhere. The PL spectra of the filtered CD solutions revealed that the emission peaks shifted according to the incident wavelength, and the centrifuged CDs synthesized with the sodium citrate surfactant lacked PL due to the absence of sp³ states. This study emphasizes the importance of CD post-treatment in CD production rather than the use of surfactants.