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Chemical Regulation of Carbon Quantum Dots from Synthesis to Photocatalytic Activity
Author(s) -
Hu Shengliang,
Tian Ruixue,
Wu Lingling,
Zhao Qing,
Yang Jinlong,
Liu Jun,
Cao Shirui
Publication year - 2013
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201300076
Subject(s) - photocatalysis , photoluminescence , surface states , band bending , materials science , photochemistry , carbon fibers , oxygen , chemical engineering , electron , nanotechnology , surface (topology) , chemistry , catalysis , optoelectronics , composite material , organic chemistry , geometry , mathematics , physics , quantum mechanics , composite number , engineering
Carbon quantum dots (CQDs) were synthesized by heating various carbon sources in HNO 3 solution at reflux, and the effects of HNO 3 concentration on the size of the CQDs were investigated. Furthermore, the oxygen‐containing surface groups of as‐prepared CQDs were selectively reduced by NaBH 4 , leading to new surface states. The experimental results show that the sizes of CQDs can be tuned by HNO 3 concentration and then influence their photoluminescent behaviors; the photoluminescent properties are related to both the size and surface state of the CQDs, but the photocatalytic activities are determined by surface states alone. The different oxygen‐containing groups on the surface of the CQDs can induce different degrees of the band bending upward, which determine the separation and combination of the electron–hole pairs. The high upward band bending, which is induced by CO and COOH groups, facilitates separation of the electron–hole pairs and then enhances high photocatalytic activity. In contrast, the low upward band bending induced by COH groups hardly prevents the electron–hole pairs from surface recombination and then exhibits strong photoluminescence. Therefore, both the photocatalytic activities and optical properties of CQDs can be tuned by their surface states.