Nickle oxide (NiO) nanostructures have also been well explored for gas sensing
applications. NiO with flower-like morphology could provide large area of contact
between electrolyte and active material, and increase the electrode’s electrochemical
activity. For e.g., rose-like NiO NPs have displayed highly sensitive gas sensing for
formaldehyde (Maduraiveeran and Jin 2017).
5.3.2.5 Metal-Based Nanomaterials
Different metals including noble and rare earth metals, have been explored for
sensing applications (Maduraiveeran and Jin 2017; Franke et al. 2006). Metal NPs
based nanosensors provide advantage of sensitivity and selectivity enhancement by
amplification of tuned signals. Lots of research has been focused for designing pure
and bio-functionalized metal nanoparticles and nanocomposites, and application of
these nanomaterials for the development of analytical techniques for environmental
monitoring (Wang et al. 2011). Noble metals i.e., gold (Au), platinum (Pt), silver
(Ag), palladium (Pd), osmium (Os), rhodium (Rh), iridium (Ir), ruthenium (Ru),
display excellent corrosion and oxidation resistance even at high temperatures
(Azharuddin et al. 2019), and thus, can be used for potential sensing applications.
As mentioned in earlier sections, metal-based NPs show unique optical properties
and can be used for fabrication of LSPR and SERS-based optical sensors. Metal NPs
like Au, Ag, Pt, Cu and Pd also display outstanding electrocatalytic behaviour.
Au NPs have distinct features like tunable optical properties, surface modification
capacity, high surface area, high stability, electrocatalytic activity, and total recovery
during electrochemical redox reactions. Au NPs have been used for modification of
electrodes for electrochemical sensing and utilized them for detection of environmental contaminants, with advantages like high sensitivity, better catalytic activity,
more signal-to-noise ratio, and better electroactive species diffusion (Wolfrum et al.
2016). Ratner and Mandler (2015) applied Au NPs for modification of electrode
surface and highly sensitive and reproducible mercury (Hg) detection. Chen and
Huang (2014) reported arsenic ion (As
3+ ) detection with low detection limit of
32.5 pM using gold-based electrochemical nanosensors, fabricated by an easy and
cost-effective method. Au NPs have also been used for successful fabrication of
nanobiosensors due to improvement of bioanalytical performances and better electron transfer between biomolecules and transducer, with inclusion of Au NPs
(Lebégue et al. 2015).
Extensive research work has been done for utilizing platinum (Pt) NPs for
electrochemical sensing, due to their electrocatalytic behaviour. The choice of
methods for incorporation of Pt NPs on the surface of electrodes play significant
role in the development of stable, chemically inert, highly catalytic nanosensors with
low background current (Govindhan et al. 2016). Several techniques for fabrication
of Pt NPs modified sensors like electrochemical deposition, chemical reduction,
photochemical deposition, metal-vapour synthesis, etc., have been well-explored.
Characteristics of Pt NPs like crystal structure, chemical composition, surface
conditions, orientation of crystallographic axis, also plays major role in their mechanism for electron transport (Govindhan et al. 2016). Pt NPs based nanosensors have
also been applied for the detection of major environmental contaminants. For
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applications. NiO with flower-like morphology could provide large area of contact
between electrolyte and active material, and increase the electrode’s electrochemical
activity. For e.g., rose-like NiO NPs have displayed highly sensitive gas sensing for
formaldehyde (Maduraiveeran and Jin 2017).
5.3.2.5 Metal-Based Nanomaterials
Different metals including noble and rare earth metals, have been explored for
sensing applications (Maduraiveeran and Jin 2017; Franke et al. 2006). Metal NPs
based nanosensors provide advantage of sensitivity and selectivity enhancement by
amplification of tuned signals. Lots of research has been focused for designing pure
and bio-functionalized metal nanoparticles and nanocomposites, and application of
these nanomaterials for the development of analytical techniques for environmental
monitoring (Wang et al. 2011). Noble metals i.e., gold (Au), platinum (Pt), silver
(Ag), palladium (Pd), osmium (Os), rhodium (Rh), iridium (Ir), ruthenium (Ru),
display excellent corrosion and oxidation resistance even at high temperatures
(Azharuddin et al. 2019), and thus, can be used for potential sensing applications.
As mentioned in earlier sections, metal-based NPs show unique optical properties
and can be used for fabrication of LSPR and SERS-based optical sensors. Metal NPs
like Au, Ag, Pt, Cu and Pd also display outstanding electrocatalytic behaviour.
Au NPs have distinct features like tunable optical properties, surface modification
capacity, high surface area, high stability, electrocatalytic activity, and total recovery
during electrochemical redox reactions. Au NPs have been used for modification of
electrodes for electrochemical sensing and utilized them for detection of environmental contaminants, with advantages like high sensitivity, better catalytic activity,
more signal-to-noise ratio, and better electroactive species diffusion (Wolfrum et al.
2016). Ratner and Mandler (2015) applied Au NPs for modification of electrode
surface and highly sensitive and reproducible mercury (Hg) detection. Chen and
Huang (2014) reported arsenic ion (As
3+ ) detection with low detection limit of
32.5 pM using gold-based electrochemical nanosensors, fabricated by an easy and
cost-effective method. Au NPs have also been used for successful fabrication of
nanobiosensors due to improvement of bioanalytical performances and better electron transfer between biomolecules and transducer, with inclusion of Au NPs
(Lebégue et al. 2015).
Extensive research work has been done for utilizing platinum (Pt) NPs for
electrochemical sensing, due to their electrocatalytic behaviour. The choice of
methods for incorporation of Pt NPs on the surface of electrodes play significant
role in the development of stable, chemically inert, highly catalytic nanosensors with
low background current (Govindhan et al. 2016). Several techniques for fabrication
of Pt NPs modified sensors like electrochemical deposition, chemical reduction,
photochemical deposition, metal-vapour synthesis, etc., have been well-explored.
Characteristics of Pt NPs like crystal structure, chemical composition, surface
conditions, orientation of crystallographic axis, also plays major role in their mechanism for electron transport (Govindhan et al. 2016). Pt NPs based nanosensors have
also been applied for the detection of major environmental contaminants. For
112
U. Chakraborty et al.