Defect States Control Effective Band Gap and Photochemistry of Graphene Quantum Dots

ACS Applied Materials & Interfaces
Mauricio A Melo, Frank E Osterloh

Abstract

Graphene quantum dots (GQDs) have emerged as a new group of quantum-confined semiconductors in recent years, with possible applications as light absorbers, luminescent labels, electrocatalysts, and photoelectrodes for photoelectrochemical water splitting. However, their semiconductor characteristics, such as the effective band gap, majority carrier type, and photochemistry, are obscured by defects in this material. Herein, we use surface photovoltage spectroscopy (SPS) in combination with photoelectrochemical measurements to determine the parameters that are essential to the use of GQDs as next-generation semiconductor devices and photocatalysts. Our results show that ordered GQDs (1-6 nm) behave as p-type semiconductors, based on the positive photovoltage in the SPS measurements on Al, Au, and fluorine-doped tin oxide substrates, and generate mobile charge carriers under excitation of defect states at 1.80 eV and under band gap excitation at 2.62 eV. Chemical reduction with hydrazine removes some defects and increases the effective band gap to 2.92 eV. SPS measurements in the presence of sacrificial electron donor and acceptors show that photochemical charge carriers can be extracted and promote redox reactions. A reduced GQDs...Continue Reading

References

Apr 5, 1973·Biochimica Et Biophysica Acta·J E O'Reilly
Oct 8, 2004·Journal of the American Chemical Society·Xiaoyou XuWalter A Scrivens
Dec 18, 2008·Chemical Society Reviews·Akihiko Kudo, Yugo Miseki
Apr 8, 2009·Nature Nanotechnology·Sungjin Park, Rodney S Ruoff
Apr 10, 2010·Journal of the American Chemical Society·Xin YanLiang-Shi Li
Aug 6, 2010·Angewandte Chemie·Sheila N Baker, Gary A Baker
May 18, 2011·Chemical Communications : Chem Comm·Shoujun ZhuBai Yang
Dec 6, 2011·Journal of the American Chemical Society·Yan LiLiangti Qu
Jan 6, 2012·Nano Letters·Juan PengPulickel M Ajayan
Mar 14, 2012·Chemical Communications : Chem Comm·Jianhua ShenChunzhong Li
Oct 18, 2012·Chemical Society Reviews·Frank E Osterloh
Jan 26, 2013·ACS Nano·Kenrick J WilliamsXiaoyang Zhu
Oct 15, 2013·Chemical Society Reviews·Chun Kiang Chua, Martin Pumera
Dec 7, 2013·Nature Communications·Ruquan YeJames M Tour
Feb 25, 2014·Journal of the American Chemical Society·Zonglong ZhuShihe Yang
Apr 8, 2015·ACS Applied Materials & Interfaces·K A Shiral FernandoYa-Ping Sun
Apr 14, 2015·Nanoscale·Shoujun ZhuBai Yang
Aug 8, 2015·Physical Chemistry Chemical Physics : PCCP·Wenkai ZhangXiaomin Fang
Mar 6, 2014·The Journal of Physical Chemistry Letters·Jing Zhao, Frank E Osterloh
May 19, 2011·The Journal of Physical Chemistry Letters·Xin YanLiang-Shi Li
Nov 4, 2015·Chemical Communications : Chem Comm·Chun Kiang Chua, Martin Pumera
Dec 17, 2015·Chemical Communications : Chem Comm·A CayuelaM Valcárcel
Apr 27, 2017·ACS Applied Materials & Interfaces·Yo-Han KimTae Seok Seo

❮ Previous
Next ❯

Citations


❮ Previous
Next ❯

Related Concepts

Trending Feeds

COVID-19

Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Blastomycosis

Blastomycosis fungal infections spread through inhaling Blastomyces dermatitidis spores. Discover the latest research on blastomycosis fungal infections here.

Nuclear Pore Complex in ALS/FTD

Alterations in nucleocytoplasmic transport, controlled by the nuclear pore complex, may be involved in the pathomechanism underlying multiple neurodegenerative diseases including Amyotrophic Lateral Sclerosis and Frontotemporal Dementia. Here is the latest research on the nuclear pore complex in ALS and FTD.

Applications of Molecular Barcoding

The concept of molecular barcoding is that each original DNA or RNA molecule is attached to a unique sequence barcode. Sequence reads having different barcodes represent different original molecules, while sequence reads having the same barcode are results of PCR duplication from one original molecule. Discover the latest research on molecular barcoding here.

Chronic Fatigue Syndrome

Chronic fatigue syndrome is a disease characterized by unexplained disabling fatigue; the pathology of which is incompletely understood. Discover the latest research on chronic fatigue syndrome here.

Evolution of Pluripotency

Pluripotency refers to the ability of a cell to develop into three primary germ cell layers of the embryo. This feed focuses on the mechanisms that underlie the evolution of pluripotency. Here is the latest research.

Position Effect Variegation

Position Effect Variagation occurs when a gene is inactivated due to its positioning near heterochromatic regions within a chromosome. Discover the latest research on Position Effect Variagation here.

STING Receptor Agonists

Stimulator of IFN genes (STING) are a group of transmembrane proteins that are involved in the induction of type I interferon that is important in the innate immune response. The stimulation of STING has been an active area of research in the treatment of cancer and infectious diseases. Here is the latest research on STING receptor agonists.

Microbicide

Microbicides are products that can be applied to vaginal or rectal mucosal surfaces with the goal of preventing, or at least significantly reducing, the transmission of sexually transmitted infections. Here is the latest research on microbicides.