CO2 selectivity of flower-like MoS2 grown on TiO2 nanofibers coated with acetic acid-treated graphitic carbon nitride

Abstract

Activated CO2 adsorption sites are crucial for improving selectivity in photocatalytic CO2 reduction. Co-catalysts incorporating rare or noble metals have previously been required to achieve high CO2 selectivity (SCO2); thus, noble-metal-free catalysts with high SCO2 are desirable but challenging to realize. We introduced S-scheme heterojunction using noble-metal-free TiO2/MoS2/graphitic carbon nitride (g-C3N4) with a strong redox ability showing SCO2 > 90%. This heterostructure improved CO2 conversion, to levels 3.1 times higher than that of the g-C3N4 alone and exhibited sufficient kinetic overpotential (0.18 eV) to produce significant amounts of CH4. When the proportion of g-C3N4 was optimized, the specified TiO2/MoS2/g-C3N4 achieved high SCO2 (~90%) due to its improved CO2 adsorption, in turn due to the improved specific surface area and pore size distribution attributable to amino (−NH2) groups of g-C3N4. We introduced, a novel, noble-metal-free TiO2/MoS2/g-C3N4 heterostructure that maximizes the number of CO2 adsorption sites and charge carriers separation through interconnected components, and thus increases SCO2.