Exceptional photocatalytic activities for CO2 conversion on AlO bridged g-C3N4/α-Fe2O3 z-scheme nanocomposites and mechanism insight with isotopesZ

Abstract It’s highly desired to design and fabricate effective Z-scheme photocatalysts by promoting the charge transfer and separation. Herein, we firstly fabricated the ratio-optimized g-C 3 N 4 /α-Fe 2 O 3 nanocomposites by adjusting the mass ratio between two components through a simple wet-chemical process. The resulting nanocomposites display much high photocatalytic activities for CO 2 conversion and phenol degradation compared to bare α-Fe 2 O 3 and g-C 3 N 4 . Noteworthily, the photocatalytic activities are further improved by constructing Al O bridges, by 4-time enhancement compared to those of α-Fe 2 O 3 . Based on the steady-state surface photovoltage spectra, transient-state surface photovoltage responses, photoelectrochemical I-t curves and the evaluation of produced OH amounts, the exceptional photoactivities of Al O bridged g-C 3 N 4 /α-Fe 2 O 3 nanocomposites are attributed to the significantly promoted charge transfer and separation by constructing the g-C 3 N 4 /α-Fe 2 O 3 heterojunctions and the Al O bridges. Moreover, the charge transfer and separation of this photocatalyst have been confirmed to obey the Z-scheme mechanism, as supported by the single-wavelength photocurrent action spectra and single-wavelength photoactivities for CO 2 conversion. Furthermore, the mechanism of the photocatalytic CO 2 conversion has been elaborately elucidated through the electrochemical reduction and the photocatalytic experiments especially with isotope 13 CO 2 and D 2 O, that the produced H atoms as intermediate radicals would dominantly induce the conversion of CO 2 to CO and CH 4 .