CO 2 Reduction to Methanol Using a Conjugated Organic–Inorganic Hybrid TiO 2 –C 3 N 4 Nano-assembly

The nanocomposite photocatalytic material, TiO2/g-C3N4, was successfully fabricated via spray drying and calcination to reduce CO2 to methanol. XRD, TEM, SEM and BET result shows the coordination of TiO2 nanoparticles with g-C3N4 nanosheets. Band edge calculation of TiO2/g-C3N4 heterostructure depicts type II heterojunction photocatalyst, for enhanced charge separation or reduced charge recombination. Our optimized result suggests the layered g-C3N4 material has close interaction with the TiO2 particles, which fosters the light-harvesting, charge transferring and electron hole pair separation to enhance the photoactivity. Significant enhancement in photo-reduction of CO2 to methanol was observed compared to bare TiO2 and g-C3N4. The yield of methanol over the composite was 31.7 µmol/gcat after 4 h of irradiation, which was 2.3 times more than those over pure C3N4. This work demonstrates the development of an efficient semiconductor composite with charge separation playing a crucial role in CO2 reduction reactions.