161
PALS
Positron annihilation lifetime spectroscopy
PCET
Proton-coupled electron transfer
R 3 N
Tertiary amines
SHE
Standard hydrogen electrode
SPR
Surface plasmon resonance
WOC
Water oxidation co-catalyst
z
The corresponding number of transferred electrons
ΔE
o
Standard redox potential
ΔG
o
Gibbs free energy
6.1 Introduction
With the apex of the production and exploiting usage of the fossil fuels at a worldwide scale, greenhouse gases emissions are skyrocketing. Besides the deleterious
impacts on the public health and global warming evidences associated with the
amplified atmospheric concentrations of greenhouse gases, particulate matter, and
other environmental pollutants, the demands for fossil fuels seem to be increasing
exponentially. The greenhouse gases are mostly generated from the large-scale processing of fuels, chemicals, metals, minerals, textiles, and other industrial sectors.
The most common greenhouse gases include carbon dioxide, sulfur hexafluoride,
nitrous oxide (N 2 O), ozone, methane, perfluorocarbons, and hydrofluorocarbons
(Nanda et al. 2016b). To check the global temperature by 2 °C through 2050 due to
global warming, the level of CO 2 should not be higher than 15 Gt every year (Alper
and Yuksel Orhan 2017).
The increased levels of greenhouse gases cause ozone layer deterioration leading
to the trapping of the heat energy within the atmosphere directly contributing to the
global warming. The respective global warming potential of CH 4 and N 2 O is 20 and
300 times more than that of CO 2 . The greenhouse gases like CO 2 , CH 4 , and N 2 O
contribute to the global warming potential by 60, 15, and 5%, respectively (Watson
et al. 1996). Moreover, atmospheric CO 2 and CH 4 concentrations are rising as
0.4–3% per annum, whereas N 2 O is growing about 0.2% (Battle et al. 1996). The
most significant anthropogenic CO 2 emissions are recognized through the land use
changes and vehicular emissions, which emit 3.4 Gt and 3 Gt CO 2 per annum
(Gerlach 2011). Figure 6.1 shows the top 20 CO 2 -emitting countries in the world
based on fuel combustion. The top five CO 2 -emitting countries are China (9040.74
MMT CO 2 ), the United States (4997.5 MMT CO 2 ), India (2066.01 MMT CO 2 ),
Russia (1468.99 MMT CO 2 ), and Japan (1141.58 MMT CO 2 ) (Union of Concerned
Scientists 2018). Among the developing countries, China and India are ranked as
the first and third highest CO 2 -emitting nations due to the mounting consumption of
petroleum-based energy, which is growing with the corresponding speeds of 3.5%
and 3.9% each year (Nanda et al. 2015). The atmospheric CO 2 concentration escalated about 4% per annum during the last few decades (Solomon et al. 2007).
6 Conversion of Carbon Dioxide into Formaldehyde
PALS
Positron annihilation lifetime spectroscopy
PCET
Proton-coupled electron transfer
R 3 N
Tertiary amines
SHE
Standard hydrogen electrode
SPR
Surface plasmon resonance
WOC
Water oxidation co-catalyst
z
The corresponding number of transferred electrons
ΔE
o
Standard redox potential
ΔG
o
Gibbs free energy
6.1 Introduction
With the apex of the production and exploiting usage of the fossil fuels at a worldwide scale, greenhouse gases emissions are skyrocketing. Besides the deleterious
impacts on the public health and global warming evidences associated with the
amplified atmospheric concentrations of greenhouse gases, particulate matter, and
other environmental pollutants, the demands for fossil fuels seem to be increasing
exponentially. The greenhouse gases are mostly generated from the large-scale processing of fuels, chemicals, metals, minerals, textiles, and other industrial sectors.
The most common greenhouse gases include carbon dioxide, sulfur hexafluoride,
nitrous oxide (N 2 O), ozone, methane, perfluorocarbons, and hydrofluorocarbons
(Nanda et al. 2016b). To check the global temperature by 2 °C through 2050 due to
global warming, the level of CO 2 should not be higher than 15 Gt every year (Alper
and Yuksel Orhan 2017).
The increased levels of greenhouse gases cause ozone layer deterioration leading
to the trapping of the heat energy within the atmosphere directly contributing to the
global warming. The respective global warming potential of CH 4 and N 2 O is 20 and
300 times more than that of CO 2 . The greenhouse gases like CO 2 , CH 4 , and N 2 O
contribute to the global warming potential by 60, 15, and 5%, respectively (Watson
et al. 1996). Moreover, atmospheric CO 2 and CH 4 concentrations are rising as
0.4–3% per annum, whereas N 2 O is growing about 0.2% (Battle et al. 1996). The
most significant anthropogenic CO 2 emissions are recognized through the land use
changes and vehicular emissions, which emit 3.4 Gt and 3 Gt CO 2 per annum
(Gerlach 2011). Figure 6.1 shows the top 20 CO 2 -emitting countries in the world
based on fuel combustion. The top five CO 2 -emitting countries are China (9040.74
MMT CO 2 ), the United States (4997.5 MMT CO 2 ), India (2066.01 MMT CO 2 ),
Russia (1468.99 MMT CO 2 ), and Japan (1141.58 MMT CO 2 ) (Union of Concerned
Scientists 2018). Among the developing countries, China and India are ranked as
the first and third highest CO 2 -emitting nations due to the mounting consumption of
petroleum-based energy, which is growing with the corresponding speeds of 3.5%
and 3.9% each year (Nanda et al. 2015). The atmospheric CO 2 concentration escalated about 4% per annum during the last few decades (Solomon et al. 2007).
6 Conversion of Carbon Dioxide into Formaldehyde