Hydrophobic Ni@N-Doped TiO2 Nanosheet Arrays-Carbon Paper Photocatalyst for CO2 Photoreduction at Tri-Phase Interfaces

Rational interphase reaction provides a feasible method to overcome the matters of insufficient adsorption of CO2 molecules at the catalytic sites and competitive hydrogen evolution reaction (HER), which can increase the formation rate and selectivity of carbon derivatives in photocatalytic CO2 reduction. Herein, a hydrophobic photocatalyst with TiO2 nanosheet arrays grown on hydrophobic carbon paper (TiO2-HCP) is fabricated using a combination of magnetron sputtering and hydrothermal method, and its unique structure not only endows it excellent light absorption and effective carrier spatial separation but also avoids the hydrophobic reagent covering reactive sites. When the interphase reaction shifts from solid-liquid diphase to gas-liquid-solid tri-phase, the photocatalytic CO2 reduction over TiO2-HCP mainly generates CO molecules and effectively suppresses HER due to the HCP suppressing the mass transfer of H2O molecules to active sites. Notably, amounts of H-2 byproduct can further react with CO2/CO to produce high value-added CH4 resultant by modifying the N-doped TiO2-HCP with nickel/nickel oxide species. In the tri-phase interfacial CO2 photoreduction system, the CH4 formation rate of Ni@N-doped TiO2-HCP reaches 134.17 mu mol m(-2) h(-1) (about 74.6% selectivity) and total carbon derivatives selectivity is about 93%.

Automated summary

Rational interphase reaction provides a feasible method to increase the formation rate and selectivity of carbon derivatives in photocatalytic CO2 reduction. In this study, a hydrophobic photocatalyst with TiO2 nanosheet arrays grown on hydrophobic carbon paper (TiO2-HCP) is fabricated. The reaction shifts to gas-liquid-solid tri-phase, generating CO molecules and effectively suppressing HER. The Ni@N-doped TiO2-HCP achieves a CH4 formation rate of 134.17 μmol m(-2) h(-1) (about 74.6% selectivity) and the total carbon derivatives selectivity is about 93%.