Blank experiments were conducted to ensure that
the product formed was due to the photoreduction
of CO2. The blank tests consists of a UV-illuminated
without the catalyst and a reaction in the dark with
the catalyst. For typical batches, 0.3 g of catalyst powder
was suspended in 300 ml of 1 M KHCO3 solution.
Ultra high purity (UHP) grade CO2 is bubbled
through the reactor for at least 30 min to purge air
and to saturate the solution. The reactor is tightly
closed during the reaction, and a magnetic stirrer agitated
the catalyst-suspended solution at the bottom to
prevent sedimentation of the catalyst. The liquid sample
was withdrawn every hour from a reactor column.
The catalyst-suspended samples were centrifuged to
separate catalyst particles from the liquid samples
and then analyzed by a GC-FID of Shimadzu
8-ATC equipped with Porapak-Q column.