Evaluation of Commercial “Carbon Quantum Dots” Sample on Origins of Red Absorption and Emission Features
Weixiong Liang,
Lin Ge,
Xiaofang Hou,
Xianyan Ren,
Liju Yang,
Christopher E. Bunker,
Christopher M. Overton,
Ping Wang,
Ya-Ping Sun
Affiliations
Weixiong Liang
Department of Chemistry and Laboratory for Emerging Materials and Technology, Clemson University, Clemson, SC 29634, USA
Lin Ge
Department of Chemistry and Laboratory for Emerging Materials and Technology, Clemson University, Clemson, SC 29634, USA
Xiaofang Hou
Department of Chemistry and Laboratory for Emerging Materials and Technology, Clemson University, Clemson, SC 29634, USA
Xianyan Ren
Department of Chemistry and Laboratory for Emerging Materials and Technology, Clemson University, Clemson, SC 29634, USA
Liju Yang
Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, Durham, NC 27707, USA
Christopher E. Bunker
Air Force Research Laboratory, Aerospace Systems Directorate, Wright-Patterson Air Force Base, Dayton, OH 45433, USA
Christopher M. Overton
Department of Chemistry and Laboratory for Emerging Materials and Technology, Clemson University, Clemson, SC 29634, USA
Ping Wang
Department of Chemistry and Laboratory for Emerging Materials and Technology, Clemson University, Clemson, SC 29634, USA
Ya-Ping Sun
Department of Chemistry and Laboratory for Emerging Materials and Technology, Clemson University, Clemson, SC 29634, USA
The commercially acquired aqueous solution of “carbon quantum dots” sample was evaluated by optical absorption and fluorescence emission methods; in reference to aqueous dispersed small carbon nanoparticles and representative carbon dots prepared from chemical functionalization of the carbon nanoparticles. The results suggest a very low content of carbon that is associated with nanoscale carbon particles/domains in the as-supplied sample; and likely significant contamination by dye-like species/mixtures. In the absence of any information on the synthesis and history of the commercial sample, the possible cause of the contamination was illustrated by an example on similar dye formation in the one-pot carbonization synthesis of “red carbon dots” from citric acid−formamide precursor mixtures under too mild processing conditions that were insufficient for the intended carbonization. The negative impacts to the carbon dots research field by the apparent proliferation and now commercial availability of carbon-deficient or even largely carbon-less “carbon quantum dots”, which are more susceptible to dye contamination or dominance, are discussed.
