Facile synthesis of g-C3N4/ LaMO3 (M: Co, Mn, Fe) composites for enhanced visible-light-driven photocatalytic water splitting

Abstract C3N4 was used as a base semiconductor for the formation of composites with LaMO3 (M: Co, Mn, Fe) perovskite powders prepared by sol-gel (SG) and solid-state (SS) through an easy impregnation method. The optical analysis showed a redshift displacement in the case of C3N4/LaMnO3 and C3N4/LaCoO3 composites due to perovskite particles act as electron traps. By photoluminescence, we elucidate that LaFeO3 generates intermediate states inside the structure of C3N4 indicating an intimate intermixing, which is also corroborated by electrochemical characterizations. The activity of the composites towards the hydrogen evolution reaction was tested under simulated solar irradiation without sacrificial agent neither noble metals. Incorporation of 2% of perovskite over C3N4 showed the best efficiencies. C3N4/2%LaFeO3 SG and C3N4/2%LaFeO3 SS showed the highest activities (140 μmol h−1 g−1 and 40 μmol h−1 g−1 respectively). These results are attributed to the better coupling between C3N4 and LaFeO3 and the formation of a type II heterostructure. Meanwhile, the activity of C3N4/LaMnO3 and C3N4/LaCoO3 composites exhibited lower performance compared with composites prepared with LaFeO3 particles, related to the creation of a type I heterostructure where the flow of charges is not efficient, limiting the photocatalytic performance.