81
On the other hand, the influence of the composition of the electrode on the carbon dioxide transformation efficiency was studied through different materials.
Malik et al. (2016) found that the presence of the Cu 2 O (111) crystal phase made the
adsorption of the intermediates on the surface of the Cu 2 O-MWCNT catalyst more
easier, which enhanced the production of methanol. Also, the presence of organic
covalent ligand, such as 3-aminopropyltriethoxysilane on the surface of TiO 2 deposited on nickel foam, enhanced the electron transferring through the electrode and
subsequently increased the produced amount of the methanol up to 153 μmol/cm
2
.h
(Wang et al. 2017).
Recently, and as a new trend, several research groups studied the enhancing of
the electrocatalytic activities of the precious metals like gallium (Ga), ruthenium
(Ru), and platinum-gold (Pt-Au) by the deposition of the pyridine (Lessio et al.
2016) and its derivatives, such as 2,2′-bipyridine (Liu et al. 2017) and 2- pyridinethiol
(Ensafi et al. 2017), respectively. Their targets were to utilize the benefits of the
homogenous catalysts in the form of the heterogeneous catalysts. The pyridine
derivatives are well known for their high catalytic activities in the field of carbon
dioxide reduction into methanol (Deerattrakul et al. 2017). These activities are
attributed to the interaction between the carbon dioxide molecules and the Brønsted
acid sites presented in the structure of the protonated pyridine derivatives (Lucio
and Shaw 2015; Lessio and Carter 2015 and Lessio et al. 2016). In the abovementioned catalysts, the role of the precious metals is not lower in importance, whereas
these metals are the main player for producing the radical hydrogen, considered as
the initiation step in the reaction (Ensafi et al. 2017).
3.3.2 Electrocatalytic Reduction of Carbon Dioxide Using
Metal Organic Frameworks
Albo et al. (2016) investigated the electrocatalytic reduction of carbon dioxide into
methanol by using copper-based metal organic frameworks (MOFs). They selected
four MOFs for the evaluation, which were (1) HKUST-1 MOF, [Cu 3 (μ 6 -C 9 H 3 O 6 ) 2 ] n ;
(2) CuAdeAce MOF, [Cu 3 (μ 3 -C 5 H 4 N 5 ) 2 ] n ; (3) CuDTA MOF, [Cu(μ-C 2 H 2 N 2 S 2 )] n ;
and (4) CuZnDTA MOF, [Cu 0.6 Zn 0.4 (μ-C 2 H 2 N 2 S 2 )] n . The maximum cumulative
Faradaic efficiencies for the carbon dioxide conversion at the MOF-based electrodes
were 15.9, 1.2, 6, and 9.9%, respectively, at a current density of 10 mAcm
−2
. These
results showed that the unsaturated coordination positions of the MOFs exposed in
the pore system enhanced the performance of the electrocatalytic reduction.
Recently, carbonized HKUST-1 MOF doped with palladium nanoparticles
showed good selectivity towards methanol, whereas the reaction energy towards
producing the methanol was 19.5 eV. Such activity could be attributed to the defects
on the carbon base that provided more active sites for intermediates adsorption and
facilitated electron transfer (Cheng et al. 2019).
3 Application of Metal Organic Frameworks in Carbon Dioxide Conversion to Methanol
On the other hand, the influence of the composition of the electrode on the carbon dioxide transformation efficiency was studied through different materials.
Malik et al. (2016) found that the presence of the Cu 2 O (111) crystal phase made the
adsorption of the intermediates on the surface of the Cu 2 O-MWCNT catalyst more
easier, which enhanced the production of methanol. Also, the presence of organic
covalent ligand, such as 3-aminopropyltriethoxysilane on the surface of TiO 2 deposited on nickel foam, enhanced the electron transferring through the electrode and
subsequently increased the produced amount of the methanol up to 153 μmol/cm
2
.h
(Wang et al. 2017).
Recently, and as a new trend, several research groups studied the enhancing of
the electrocatalytic activities of the precious metals like gallium (Ga), ruthenium
(Ru), and platinum-gold (Pt-Au) by the deposition of the pyridine (Lessio et al.
2016) and its derivatives, such as 2,2′-bipyridine (Liu et al. 2017) and 2- pyridinethiol
(Ensafi et al. 2017), respectively. Their targets were to utilize the benefits of the
homogenous catalysts in the form of the heterogeneous catalysts. The pyridine
derivatives are well known for their high catalytic activities in the field of carbon
dioxide reduction into methanol (Deerattrakul et al. 2017). These activities are
attributed to the interaction between the carbon dioxide molecules and the Brønsted
acid sites presented in the structure of the protonated pyridine derivatives (Lucio
and Shaw 2015; Lessio and Carter 2015 and Lessio et al. 2016). In the abovementioned catalysts, the role of the precious metals is not lower in importance, whereas
these metals are the main player for producing the radical hydrogen, considered as
the initiation step in the reaction (Ensafi et al. 2017).
3.3.2 Electrocatalytic Reduction of Carbon Dioxide Using
Metal Organic Frameworks
Albo et al. (2016) investigated the electrocatalytic reduction of carbon dioxide into
methanol by using copper-based metal organic frameworks (MOFs). They selected
four MOFs for the evaluation, which were (1) HKUST-1 MOF, [Cu 3 (μ 6 -C 9 H 3 O 6 ) 2 ] n ;
(2) CuAdeAce MOF, [Cu 3 (μ 3 -C 5 H 4 N 5 ) 2 ] n ; (3) CuDTA MOF, [Cu(μ-C 2 H 2 N 2 S 2 )] n ;
and (4) CuZnDTA MOF, [Cu 0.6 Zn 0.4 (μ-C 2 H 2 N 2 S 2 )] n . The maximum cumulative
Faradaic efficiencies for the carbon dioxide conversion at the MOF-based electrodes
were 15.9, 1.2, 6, and 9.9%, respectively, at a current density of 10 mAcm
−2
. These
results showed that the unsaturated coordination positions of the MOFs exposed in
the pore system enhanced the performance of the electrocatalytic reduction.
Recently, carbonized HKUST-1 MOF doped with palladium nanoparticles
showed good selectivity towards methanol, whereas the reaction energy towards
producing the methanol was 19.5 eV. Such activity could be attributed to the defects
on the carbon base that provided more active sites for intermediates adsorption and
facilitated electron transfer (Cheng et al. 2019).
3 Application of Metal Organic Frameworks in Carbon Dioxide Conversion to Methanol