| Biophotosynthetic |
An approach that mimics
natural photosynthesis, which usually involves redox enzyme molecules
as photocatalysts or artificial microbes for photosynthesis |
| Photothermal |
An approach that uses high-temperature
solar reactors, typically employing concentrated solar radiation,
to split CO2, potentially utilizing the entire solar spectrum
and offering high product formation rate |
| Microbial-photoelectrochemical |
Combines the advantages
of semiconductor photoelectrodes and the high-selectivity microbe-based
biocatalysts, directly converting CO2 into fuels or chemicals |
| Photosynthetic
and photocatalytic
(PS/PC) |
Two sister
approaches using
particulate or molecular photocatalysts, either in solution or immobilized
on a surface. This category includes both PC (ΔG < 0) and PS (ΔG > 0) processes, depending
on the oxidation half reaction. Because of many similarities, they
are discussed together herein, but in the light-to-fuel efficiency
comparison (Figure 9b), only PS processes were selected to ensure fair comparison. |
| Photoelectrochemical
(PEC) |
Either one
or both electrodes
of the electrochemical cell is/are semiconductor photoelectrode(s).
Photogenerated charge carriers drive either one or both half reactions.
We included studies using the “buried junction” concept
here, where a solar cell is covered by one or more catalyst(s) (and
possibly a protecting layer) and this whole assembly acts as a photoelectrode. |
| Photovoltaic
plus electrochemical
(PV+EC) |
The combination
of PV cells
with CO2 electrolysis in one device. This approach decouples
the light-harvesting and the electrochemical conversion steps. |
