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

- Photocatalytic activities of α-Fe2O3 for CO2 conversion are improved by fabricating nanocomposites with g-C3N4.
- Photocatalytic activities of g-C3N4/α-Fe2O3 nanocomposites could be further improved by building AlO bridges.
- Improved photoactivities are attributed to enhanced photogenerated charge transfer and separation.
- Charge transfer and separation in resulting AlO bridged nanocomposites obey a Z-scheme mechanism.
- It is confirmed produced H atoms are feasible to induce conversion of CO2 by means of isotope experiments.

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-C3N4/α-Fe2O3 nanocomposites by adjusting the mass ratio between two components through a simple wet-chemical process. The resulting nanocomposites display much high photocatalytic activities for CO2 conversion and phenol degradation compared to bare α-Fe2O3 and g-C3N4. Noteworthily, the photocatalytic activities are further improved by constructing AlO bridges, by 4-time enhancement compared to those of α-Fe2O3. 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 AlO bridged g-C3N4/α-Fe2O3 nanocomposites are attributed to the significantly promoted charge transfer and separation by constructing the g-C3N4/α-Fe2O3 heterojunctions and the AlO 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 CO2 conversion. Furthermore, the mechanism of the photocatalytic CO2 conversion has been elaborately elucidated through the electrochemical reduction and the photocatalytic experiments especially with isotope 13CO2 and D2O, that the produced H atoms as intermediate radicals would dominantly induce the conversion of CO2 to CO and CH4.

Built AlO bridges could promote charge transfer and separation in fabricated Z-scheme g-C3N4/α-Fe2O3 nanocomposite for improved photoactivities.127