Investigation of hydrophobic MoSe2 grown at edge sites on TiO2 nanofibers for photocatalytic CO2 reduction

We introduce noble metal-free TiO2/MoSe2 heterostructures to achieve high yields and high selectivity during the artificial photosynthesis of CO2 via a reduction process. It demonstrated CH4 production amount of 174.02 μmol/g, and CO production amount of 478.46 μmol/g, with CO2 selectivity of 80%. We fabricated uniform MoSe2 nanosheets grown at edge sites on TiO2 nanofibers using a solvothermal method. These MoSe2 nanosheet heterostructures were classified as overgrown, full-grown, or partially grown. Fully and uniformly grown MoSe2 nanosheets on TiO2 nanofibers, at 3% TiO2/MoSe2 (with 3% atomic ratio of Ti/Mo), showed superior photocatalytic CO2 reduction due to the very large specific surface area and high CO2 adsorption ability. Moreover, the high contact angle (~113°) indicated a hydrophobic surface, which suppressed H2O contact and production of protons for H2 formation, while also enhancing contact with CO2 to promote photocatalytic CO2 reduction. Based on this, 3% TiO2/MoSe2 displayed the highest CO2 selectivity, of 80%, among the heterostructures. The noble metal-free TiO2/MoSe2 heterostructure with uniform growth of MoSe2 nanosheets, having abundant CO2 adsorption sites and a highly hydrophobic surface, facilitated electron transport through the interface between TiO2 and MoSe2. The edge sites on the MoSe2 basal plane enabled a strong redox reaction at the surface, which enhanced the amounts of CO and CH4 gases via photocatalytic CO2 reduction.