aluminium (8.1%), silicon (27%) and unfortunately, the photocatalyst research
developments did not integrate the materials for the water remediation. The popular
choice the materials are titanium (0.66%), cadmium (1.5 Â 10
À5 %), zinc (0.0078%),
copper (0.0068%), silver (7.9 Â 10
À6 %), bismuth (2.5 Â 10
À6 %), tin (0.00022%)
and Nickel (0.009%). Ironically, state-of-art material titanium is existing in earth
about 0.66%. The materials also have the issue of extraction technology where
primary and daughter materials extraction (Graedel 2011). The daughter materials
are materials extracted along with side of primary materials which cannot be
extracted separately. Notable primary materials copper, nickel, zinc, lead and aluminium. For example, copper is extracted as primary materials and the daughter
materials of the copper are cobalt, selenium, tellurium. Explaining the influence of
extraction technologies in abundance is beyond the scope of present work. Hence,
the research direction of photocatalytic water remediation towards the high abundant
materials, ideally aluminium and oxygen. The materials abundance is new scarcity
and makes the photocatalytic technology costly for commercialization as well as
implementation. Therefore, we suggest that if we controllably design and prepare the
earth abundant photocatalyst, we could realize photocatalyst based water remediation technology.
unconsciously, very few excellent efforts addressed the environmental issue in
the current literature. Our intention is not to present exhaustive review of the
reported work on abundant materials, but rather to note new research direction and
reported the representative examples. We presented mostly oxides of high abundant
and moderately abundant materials.
7.2.1 Aluminium Compounds as Earth Abundant Materials
If we focus about the earth abundant material research, aluminium is an ideal choice
of cation. But the aluminium is suffered by its high band gap and not been the
favorable choice of materials. But the novel compounds like metal organic frame
works (MOFs) may integrate the aluminum in photocatalytic research. Fujita et al.
initially revealed potential use of the MOFs as heterogeneous catalyst (Fujita et al.
1994). MOFs have active metal ion at the surface and inside cavity provides high
regioselectivity, stereoselectivity, and shape selectivity for the photocatalytic applications. MOFs have wide attention due to the fact that, the cavity shape, size and
surface metal atoms of MOFs can be tuned to the required level of photocatalysis.
The MOFs is combination of organic molecules with inorganic metals and hence it
provides excellent chemical tunability to photocatalyst which help to optimise the
catalyst for best performance. After that, Martín et al. reported that ruthenium
complexation with aluminium metal–organic framework and its application in
alcohol oxidation catalysis with high selectivity (Carson et al. 2012). Along with
the aluminium, bipyridine and ruthenium in the metal organic frame work. The
aluminium was introduced in the metal organic frame works through the post
synthetic modification. The introduction of the aluminium provide the stability,
7 Earth Abundant Materials for Environmental Remediation and Commercialization
205
developments did not integrate the materials for the water remediation. The popular
choice the materials are titanium (0.66%), cadmium (1.5 Â 10
À5 %), zinc (0.0078%),
copper (0.0068%), silver (7.9 Â 10
À6 %), bismuth (2.5 Â 10
À6 %), tin (0.00022%)
and Nickel (0.009%). Ironically, state-of-art material titanium is existing in earth
about 0.66%. The materials also have the issue of extraction technology where
primary and daughter materials extraction (Graedel 2011). The daughter materials
are materials extracted along with side of primary materials which cannot be
extracted separately. Notable primary materials copper, nickel, zinc, lead and aluminium. For example, copper is extracted as primary materials and the daughter
materials of the copper are cobalt, selenium, tellurium. Explaining the influence of
extraction technologies in abundance is beyond the scope of present work. Hence,
the research direction of photocatalytic water remediation towards the high abundant
materials, ideally aluminium and oxygen. The materials abundance is new scarcity
and makes the photocatalytic technology costly for commercialization as well as
implementation. Therefore, we suggest that if we controllably design and prepare the
earth abundant photocatalyst, we could realize photocatalyst based water remediation technology.
unconsciously, very few excellent efforts addressed the environmental issue in
the current literature. Our intention is not to present exhaustive review of the
reported work on abundant materials, but rather to note new research direction and
reported the representative examples. We presented mostly oxides of high abundant
and moderately abundant materials.
7.2.1 Aluminium Compounds as Earth Abundant Materials
If we focus about the earth abundant material research, aluminium is an ideal choice
of cation. But the aluminium is suffered by its high band gap and not been the
favorable choice of materials. But the novel compounds like metal organic frame
works (MOFs) may integrate the aluminum in photocatalytic research. Fujita et al.
initially revealed potential use of the MOFs as heterogeneous catalyst (Fujita et al.
1994). MOFs have active metal ion at the surface and inside cavity provides high
regioselectivity, stereoselectivity, and shape selectivity for the photocatalytic applications. MOFs have wide attention due to the fact that, the cavity shape, size and
surface metal atoms of MOFs can be tuned to the required level of photocatalysis.
The MOFs is combination of organic molecules with inorganic metals and hence it
provides excellent chemical tunability to photocatalyst which help to optimise the
catalyst for best performance. After that, Martín et al. reported that ruthenium
complexation with aluminium metal–organic framework and its application in
alcohol oxidation catalysis with high selectivity (Carson et al. 2012). Along with
the aluminium, bipyridine and ruthenium in the metal organic frame work. The
aluminium was introduced in the metal organic frame works through the post
synthetic modification. The introduction of the aluminium provide the stability,
7 Earth Abundant Materials for Environmental Remediation and Commercialization
205