Page 142 - Polymer-based Nanocomposites for Energy and Environmental Applications

Energy and environmental applications of graphene and its derivatives 117

fields of electrochemical sensing and bioanalysis to measure the release of H 2 O 2 from
living cells [81]. Developed HRP/PGN/GCE biosensor can facilitate the electron
transfer of HRP and improve analytic performance for the determination of H 2 O 2 ,
by combining the outstanding features of PGN, combined with the excellent selective
catalysis of HRP [81]. Moreover, functionalized graphene or graphene composites
constitute the basis for fabrication of various kinds of electrodes dedicated to detection
of a wide range of chemical and biochemical species, such as dopamine, antigens,
ascorbic acid, H 2 O 2 , glucose, DNA, or nucleic acid [82].

4.5.1 Heavy metal ions detection
In other study, graphene modified with carboxylic groups (GCOOH) was used in the
development of sensor for electrochemical detection of uranyl ion, chemically toxic
and radioactive inorganic compounds, inevitably released into the environment lead-
ing to serious health problems [82]. The GCOOH sensor response was found linear in
1
the concentration range from 0.05 to 5 μmol L , meeting the detection limits defined
1
by USEPA in drinking water (130 nmol L ). GCOOH is also considered as promis-
ing electrode material for further sensor construction optimization (e.g., with the
additional use of nucleic acids as the receptor layer) [83].
Literature review also justified the existence of disposable sensor modified with GO
doped diaminoterthiophene (GO/DTT) for chronocoulometry (CC) for the rapid and
2+
2+
2+
simultaneous determination of cadmium Cd , lead Pb , copper Cu , and mercury
Hg 2+ ions [84]. Recently, iron oxide (Fe 2 O 3 )/graphene (G) nanocomposite electrode
used in combination with in situ plated bismuth (Bi) as an electrochemical sensor
2+
2+
for the determination of trace zinc (Zn ), Cd , and Pb 2+ [85]. In other study, GQDs
are functionalized in cysteamine-capped gold NPs for electrochemical detection of
mercury ions Hg 2+ with a detection limit of 0.02 nM, using anodic stripping
2+
voltammetry (ASV) method. Besides Hg , sensor can also detect Cu 2+ at a
concentration as low as 0.05 nM [86]. Literature also claimed a sensitive electrochem-
2+
2+
2+
ical platform for the simultaneous determination of Cu ,Cd ,Pb 2+ and Hg , based
on N-doped graphene (NG) modified electrode, using differential pulse stripping
voltammetry (DPSV) [87]. The NG-modified electrode offered an excellent selectiv-
2+
2+
2+
ity, stability, and sensitivity for the analysis of Cu ,Cd ,Hg , and Pb 2+ due to its
unique electronic properties and particular structure. The developed sensor was also
2+
2+
2+
effectively applied for the detection of trace Cd ,Hg ,Cu , and Pb 2+ in tap water
with satisfactory results. The adsorption and coadsorption of naphthalene, 1-naphthol,
and Cd 2+ onto GO, chemically reduced graphene (CRG), and annealing reduced
graphene (ARG) were also reported [88]. In other research study, graphene ultrathin
films were fabricated via solid-state carbon diffusion using a-C layer as the carbon
source. This film positively been used as an electrochemical sensor for detection of
2+
trace heavy metal ions (Pb ) contained in an acetate buffer solution (pH 5.3) with
a detection limit of about 7 nM [89]. Besides this several works has been reported
by researchers for the selective sensing of chemicals and toxic materials are listed
in Table 4.1.