monitoring and detection of heavy metal ions in the environment. The benefits of
these types of sensors are that these are highly sensitive and selective towards
electroactive species, low detection limit, inexpensive, portable, high accuracy and
easily packable device, etc. [31–33]. Carbon-based electrodes such as glassy carbon,
graphitic carbon, etc. have been already replaced over other metal electrodes substances in electrochemical and analytical fields. These materials show some outstanding properties over metal electrodes like chemical stability, low cost,
electrocatalytic activity for a variety of redox reactions and possess wide potential
applications.
This chapter discusses mostly plasmonic nanoparticles decorated graphene and
functionalized graphene system for the sensing application of hazardous water
pollutant like heavy metal ions, organic pollutants, etc. The recent progress based
on fluorometric, colorimetric, and electrochemical detection techniques using
decorated graphene surface for detection of water pollutants mostly heavy metal
ions is also briefly discussed in this chapter.
2 Synthesis of Graphene Oxide
The oxygen-rich functionality of graphene, which is prepared by the oxidation of
commercially or naturally available graphite powder, is termed as graphene oxide.
In 1958, Hummers and Offeman developed a faster, safer, and the most efficient
route for the synthesis of oxidized graphite. Before this method, some other
methods like Brodie methods 1859, Staudenmaier method 1898 were developed.
But graphite oxide production was very slow, and the final product contains hazardous ions due to the use of concentrated H 2 SO 4 and HNO 3 . This method is
regarded as a better method over other reported methods that time. In the Hummers
and Offeman method, graphite oxidation is carried out with a mixture of H 2 SO 4 ,
NaNO 3 , and KMnO 4 . Nowadays, a modified Hummers and Offeman method are
generally used [34]. In this method, oxidation has been carried out in the absence of
NaNO 3 . The reaction between KMnO 4 and H 2 SO 4 leads to dimanganese heptoxide
(Mn 2 O 7 ), which acts as a strong oxidizing agent for this reaction to generate graphite oxide (Eqs. 1 and 2). The extensive oxidation of graphite to graphene oxide is
depicted in schematically in Fig. 1.
KMnO 4 þ 3 H 2 SO 4 ! K
þ
þ MnO
þ
3 þ H 3 O
þ
þ 3 HSO
À
4
ð1Þ
MnO
þ
3 þ MnO 4 ! Mn 2 O 7
ð2Þ
Characterization of Graphene Oxide
The GO dispersion was characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), UV-visible spectroscopy, XPS and Raman
82
M. J. Deka et al.
these types of sensors are that these are highly sensitive and selective towards
electroactive species, low detection limit, inexpensive, portable, high accuracy and
easily packable device, etc. [31–33]. Carbon-based electrodes such as glassy carbon,
graphitic carbon, etc. have been already replaced over other metal electrodes substances in electrochemical and analytical fields. These materials show some outstanding properties over metal electrodes like chemical stability, low cost,
electrocatalytic activity for a variety of redox reactions and possess wide potential
applications.
This chapter discusses mostly plasmonic nanoparticles decorated graphene and
functionalized graphene system for the sensing application of hazardous water
pollutant like heavy metal ions, organic pollutants, etc. The recent progress based
on fluorometric, colorimetric, and electrochemical detection techniques using
decorated graphene surface for detection of water pollutants mostly heavy metal
ions is also briefly discussed in this chapter.
2 Synthesis of Graphene Oxide
The oxygen-rich functionality of graphene, which is prepared by the oxidation of
commercially or naturally available graphite powder, is termed as graphene oxide.
In 1958, Hummers and Offeman developed a faster, safer, and the most efficient
route for the synthesis of oxidized graphite. Before this method, some other
methods like Brodie methods 1859, Staudenmaier method 1898 were developed.
But graphite oxide production was very slow, and the final product contains hazardous ions due to the use of concentrated H 2 SO 4 and HNO 3 . This method is
regarded as a better method over other reported methods that time. In the Hummers
and Offeman method, graphite oxidation is carried out with a mixture of H 2 SO 4 ,
NaNO 3 , and KMnO 4 . Nowadays, a modified Hummers and Offeman method are
generally used [34]. In this method, oxidation has been carried out in the absence of
NaNO 3 . The reaction between KMnO 4 and H 2 SO 4 leads to dimanganese heptoxide
(Mn 2 O 7 ), which acts as a strong oxidizing agent for this reaction to generate graphite oxide (Eqs. 1 and 2). The extensive oxidation of graphite to graphene oxide is
depicted in schematically in Fig. 1.
KMnO 4 þ 3 H 2 SO 4 ! K
þ
þ MnO
þ
3 þ H 3 O
þ
þ 3 HSO
À
4
ð1Þ
MnO
þ
3 þ MnO 4 ! Mn 2 O 7
ð2Þ
Characterization of Graphene Oxide
The GO dispersion was characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), UV-visible spectroscopy, XPS and Raman
82
M. J. Deka et al.