The photocatalytic experiment for the reduction of CO2 was
performed at ambient temperature (25 5 C) in a continuous
gas ow reactor. The volume of the cylindrical reactor which
was made of stainless steel and covered with quartz-glass was
300 ml (11 cm 4 cm). One sample dish containing 0.2 g of
catalyst powder was placed in the middle of the reactor. A 300W
commercial halogen lamp was used as the simulated solar-light
source. The lamp was vertically placed outside the reactor above
the sample dish. Two mini fans were xed around the lamp to
avoid the temperature rise of the ow system. The catalyst
powder spread onto a glass disc, with a diameter of 7.5 cm.
Initially nitrogen gas was purged inside the reactor to remove
the air with other gases. Aer that CO2 was purged inside the
reactor for another 1 hour and the ow rate was controlled at 4
sccm. CO2 was owing through water to control the desired
humidity level for the entire experiment. The halogen lamp was
turned on aer one hour while adsorption and desorption of the
gas and the photocatalyst reached the equilibrium. The
concentration of methanol was continuously measured by a GCFID
in the vapor phase. The detailed schematic drawing of the
experimental setup is shown in Fig. S1