期刊
JOURNAL OF COLLOID AND INTERFACE SCIENCE
卷 527, 期 -, 页码 132-140出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2018.04.113
关键词
Graphene quantum dots; Laser ablations; Photoluminescence lifetime
资金
- National Science Foundation Division of Chemistry [CHE-1362102]
- University of Kentucky Research Challenge Trust Fund
- National Science Foundation [1355438]
- NSF EPSCoR grant [0814194]
- Kentucky Science and Engineering Foundation
- Division Of Chemistry [1362102] Funding Source: National Science Foundation
Graphene quantum dots (GQDs) have been synthesized reproducibly by chemical oxidation (CO) of carbon nano-onions (nCNOs) and a one-step pulsed laser ablation (LA) of nCNOs in deionized water. The photoluminescence (PL) spectra show that the LA-GQDs have blue shifted emission relative to the CO-GQDs which is attributed to the effects of both particle sizes and surface functional groups. The CO-GQDs have an average diameter of 4.1(8) nm and a thickness corresponding to two or three graphene layers, while the LA-GQDs have an average diameter of 1.8(6) nm and a thickness comparable to a single layer of graphene. The CO-GQDs favor the presence of carboxylic groups and have a higher fraction of sp(2) carbons, while the LA-GQDs prefer the presence of hydroxyl groups and have a higher fraction of sp(3) carbons. PL lifetime data suggests that surface functional groups are the main source of radiative deactivation and the sp(2) carbon domains are mainly responsible for non-radiative decay. PL lifetimes are measured to be 7.9(6) ns for the emission from the carboxylic groups and 3.18(10) ns from the hydroxyl groups. Compared to CO, liquid-phase LA is a faster and cleaner one-step method for producing GQDs with fewer starting chemicals and byproducts. (C) 2018 Elsevier Inc. All rights reserved.
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