Heterojunction p-n-p Cu2O/S-TiO2/CuO: Synthesis and application to photocatalytic conversion of CO2 to methane

Abstract

Photocatalytic conversion of CO2 to fuel is a topic of great current interest. The problem is a challenging one, requiring a photocorrosion-stable, industrially-scalable, broad-spectrum light absorbing semiconductor, the energy bands of which align with the CO/CO2 and H2O/O2 potentials. Herein we report the synthesis of a unique p-n-p heterojunction material architecture, Cu2O/S-doped TiO2 micro-blocks covered with CuO nanowires, using anodization and annealing processes. The photocatalytic material shows excellent performance in the photocatalytic conversion of CO2 and water vapor to methane under AM 1.5G illumination. The heterojunction material architecture exhibits a methane yield of 2.31μmolm−2h−1, a rate approximately ten times higher than TiO2 nanotube array films synthesized using similar anodization conditions. The improved performance of the heterojunctioned material architecture appears due to improved light absorption and efficient separation of the photogenerated charge.