Controlled, Stepwise Reduction and Band Gap Manipulation of Graphene Oxide.
Graphene oxide (GO) has drawn tremendous interest as a tunable precursor in numerous areas, due to its readily manipulable surface. However, its inhomogeneous and nonstoichiometric structure makes achieving chemical control a major challenge. Here, we present a room-temperature based, controlled method for the stepwise reduction of GO, with evidence of sequential removal of each organic moiety. By analyzing signature infrared absorption frequencies, we identify the carbonyl group as the first to be reduced, while the tertiary alcohol takes the longest to be completely removed from the GO surface. Controlled reduction allows for progressive tuning of the optical gap from 3.5 eV down to 1 eV, while XPS spectra show a concurrent increase in the C/O ratio. This study is the first step toward selectively enhancing the chemical homogeneity of GO, thus providing greater control over its structure, and elucidating the order of removal of functional groups and hydrazine-vapor reduction.
Akshay
A
Mathkar
‡Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States.
Dylan
D
Tozier
Paris
P
Cox
Peijie
P
Ong
Charudatta
C
Galande
Kaushik
K
Balakrishnan
Arava
A
Leela Mohana Reddy
Pulickel M
PM
Ajayan
functional groups; graphene oxide; optical gap; reduction; selective