80
(440 nm) in a continuous-flow reactor system. These good activities were attributed
to the small band gap of the MOF. Such band gap resulted from the unique structure
of the MOF, which included the Cu 4 N cluster in the core of MOF in addition to the
C=N band in the imidazole ring.
Also, Cu-Al 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin MOF achieved
good photocatalytic reduction of carbon dioxide to methanol (~8200 μmol/g.h) than
the parent aluminum MOF, which produced the methanol in rate 1190 μmol/g.h
(Liu et al. 2013b). This activity was attributed to the enhancing of the adsorption
and the activation of carbon dioxide species in the presence of copper ions.
3.3 Electrocatalytic Reduction of Carbon Dioxide
Recently, the studies of the electrocatalytic reduction of CO 2 into methanol have
attracted several researchers to achieve extensive works. The main reason could be
the green nature of these researches. Whereas, the electrocatalytic reduction processes depend on the presence of electrical current that are passing through the
electrolyte and electrodes at certain conditions, such as the potential and the temperature. Such process could be based on the electrical current produced via the
renewable energy. This means a successive reducing of the carbon dioxide in the
environment (Feng et al. 2015; Geioushy et al. 2017). However, the up-scaling of
the produced amount of methanol to the industrial scale is still a serious challenge
faced by the researchers in this field.
3.3.1 Electrocatalytic Reduction of Carbon Dioxide Using
Transition Metal Catalysts
Based on their unique characterized active d-electrons, transition metal elements are
well known for their catalytic activities towards the electroreduction of carbon dioxide to methanol. The unique properties of the transition metals make the adsorption
and desorption steps more efficient. The two steps are the essential steps in any catalytic reaction (Ma et al. 2015).
Ti/ZnO–Fe 2 O 3 composite succeeds to produce 258 μmol methanol/cm
2
.h. The
mechanism of the reaction was achieved via the formation of formic acid, which
transferred to formaldehyde and finally converted into methanol. The role of the
applied electric field was found to accelerate the production and the transfer of electrons and successively to enhance the photoelectroreduction feature of the composite (Xia et al. 2016).
T. Zaki
(440 nm) in a continuous-flow reactor system. These good activities were attributed
to the small band gap of the MOF. Such band gap resulted from the unique structure
of the MOF, which included the Cu 4 N cluster in the core of MOF in addition to the
C=N band in the imidazole ring.
Also, Cu-Al 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin MOF achieved
good photocatalytic reduction of carbon dioxide to methanol (~8200 μmol/g.h) than
the parent aluminum MOF, which produced the methanol in rate 1190 μmol/g.h
(Liu et al. 2013b). This activity was attributed to the enhancing of the adsorption
and the activation of carbon dioxide species in the presence of copper ions.
3.3 Electrocatalytic Reduction of Carbon Dioxide
Recently, the studies of the electrocatalytic reduction of CO 2 into methanol have
attracted several researchers to achieve extensive works. The main reason could be
the green nature of these researches. Whereas, the electrocatalytic reduction processes depend on the presence of electrical current that are passing through the
electrolyte and electrodes at certain conditions, such as the potential and the temperature. Such process could be based on the electrical current produced via the
renewable energy. This means a successive reducing of the carbon dioxide in the
environment (Feng et al. 2015; Geioushy et al. 2017). However, the up-scaling of
the produced amount of methanol to the industrial scale is still a serious challenge
faced by the researchers in this field.
3.3.1 Electrocatalytic Reduction of Carbon Dioxide Using
Transition Metal Catalysts
Based on their unique characterized active d-electrons, transition metal elements are
well known for their catalytic activities towards the electroreduction of carbon dioxide to methanol. The unique properties of the transition metals make the adsorption
and desorption steps more efficient. The two steps are the essential steps in any catalytic reaction (Ma et al. 2015).
Ti/ZnO–Fe 2 O 3 composite succeeds to produce 258 μmol methanol/cm
2
.h. The
mechanism of the reaction was achieved via the formation of formic acid, which
transferred to formaldehyde and finally converted into methanol. The role of the
applied electric field was found to accelerate the production and the transfer of electrons and successively to enhance the photoelectroreduction feature of the composite (Xia et al. 2016).
T. Zaki