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

C 3 N 4 was used as a base semiconductor for the formation of composites with LaMO 3 (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 C 3 N 4 /LaMnO 3 and C 3 N 4 /LaCoO 3 composites due to perovskite particles act as electron traps. By photoluminescence, we elucidate that LaFeO 3 generates intermediate states inside the structure of C 3 N 4 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 C 3 N 4 showed the best efficiencies. C 3 N 4 /2%LaFeO 3 SG and C 3 N 4 /2%LaFeO 3 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 C 3 N 4 and LaFeO 3 and the formation of a type II heterostructure. Meanwhile, the activity of C 3 N 4 /LaMnO 3 and C 3 N 4 /LaCoO 3 composites exhibited lower performance compared with composites prepared with LaFeO 3 particles, related to the creation of a type I heterostructure where the flow of charges is not efficient, limiting the photocatalytic performance. Image 1 • C 3 N 4 /LaMO 3 (M: Co, Mn, Fe) were prepared by an impregnation method. • H 2 evolution tests were performed without sacrificial agents or co-catalysts. • C 3 N 4 /2% LaFeO 3 SG exhibited the highest H 2 evolution (140 μmol g−1 h−1). • H 2 production of C 3 N 4 was 14 times improved through type II heteroestructure. • C 3 N 4 /LaCoO 3 and C 3 N 4 /LaMnO 3 show a type I heterostructure with lower efficiency. [ABSTRACT FROM AUTHOR]