Journal
JOURNAL OF PHYSICAL CHEMISTRY C
Volume 126, Issue 34, Pages 14642-14649Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcc.2c0317314642J
Keywords
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Funding
- National Natural Science Foundation of China [22004085, 51671004]
- Regional Joint Fund of Guangdong Province [2019A1515111054]
- Natural Science Foundation of SZU [860-000002110386]
- Instrumental Analysis Center of Shenzhen University
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This study developed a simple electrochemical method for probing the microscopic composition of colloidal lead sulfide quantum dots, providing a quantitative analysis of their surface composition and size-dependent composition.
The size and composition of colloidal lead sulfide (PbS) quantum dots (QDs) are closely related to their optoelectronic properties, such as the band structure, carrier transportation, resistivity toward surface oxidation, etc., and hence would greatly affect the device performance. In this work, we developed a simple electrochemical methodology for probing the microscopic composition of the PbS QDs capped with oleic acid (OA). Cathodic and anodic voltammetry of PbS-OA QDs dropcast onto an electrode surface corresponding to the reduction of lead(II) and the oxidation of sulfide was separately investigated to quantify the amount of lead and sulfur. The submonolayer QDs underwent complete electrolysis at low potential scan rates, while under high scan rates, the larger reduction to oxidation charge ratio reflects that probably, only the Pb(II)-rich surface layer was electrolyzed. Based on the controllable electrolysis, not only the surface composition was revealed, but also, a depth profile of the elemental distribution for PbS-OA QDs was proposed. In addition, the size-dependent composition of PbS-OA QDs was also successfully determined, demonstrating it as a powerful tool for quantifying the composition of QDs.
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