According to Global Carbon Project, the CO2 emission for 2018 has reached a new record
of 37.1 billion metric ton. This figure is higher than those of previous years. The carbon
dioxide emission has been a primary issue to address because it absorps infrared radiation
and subsequently rises the atmospheric temperature. As a result it causes detrimental
effects for the Earth such as the notorious Green House Gas Phenomenon and climate
change. In response to the rising carbon dioxide emission, superpower countries such as
China and USA have been trying to reduce the emission by gradually switching to
renewable energy sources. A particular method that is expected to reduce the carbon
dioxide emission is the carbon dioxide photoreduction.
The carbon dioxide photoreduction can be referred as artificial photosynthesis. Although
the brief mechanism of photosynthesis is reducing carbon dioxide to glucose, there exists
a need to reduce carbon dioxide to formic acid first. Because such artificial photosynthesis
is executed at room temperature, atmospheric pressure, and under direct sun light, this
reaction requires photosensitizers to enable the solar energy to reduce carbon dioxide.
Aside from reducing the carbon dioxide emission, this pathway is also able to convert it
to valuable compound, which is formic acid, whose application in energy is a Liquid
Organic Hydrogen Carrier (LOHC).
This explorative research is aimed to photocatalytically reduce CO2 with
Zn6Cr2(OH)16CO3.4H2O concocted with varied drying time. The photocatalyst has 51.3%
crystalinity and is theoretically active with red to orange visible light. Literature study
shows that Zn is a metal commonly found in carbonic anhydrase and Cr in formate
dehydrogenase, enzymes responsible for photosynthesis and reversible conversion of
carbon dioxide to formic acid, which implies that both are metals promising in
photocatalytic reduction of carbon dioxide to formic acid.