Loading MnCo2O4@Pt on composite of g-C3N4 and covalent organic frameworks (COFs) for photocatalytic overall water splitting

The photocatalytic overall water splitting (OWS) using organic photocatalysts presents a significant challenge, primarily due to the susceptibility of these catalysts to oxidation by photogenerated holes. One effective strategy to overcome this issue involves loading a suitable co-catalyst for the oxygen evolution reaction (OER), which facilitates hole transfer and thereby inhibits catalyst oxidation, enabling successful OWS. Herein, we introduce a novel approach involving the oriented deposition of MnCo2O4 on pre-deposited Pt nanoparticles as an OER co-catalyst for a composite of g-C3N4 and TaPt-TP-COF (CNCOF). The process entails an in situ reduction of Co2+ to Co by active atomic H generated on the Pt surface, followed by a hydrothermal treatment with MnSO4 solution. The resulting MnCo2O4@Pt@CNCOF demonstrates enhanced light absorption capacity and superior photoelectrochemical properties compared to CNCOF. The MnCo2O4 improves charge separation and effectively mitigates the self-oxidation of CNCOF caused by photogenerated holes. Furthermore, with the assistance of Ag@Cr2O3 as a hydrogen evolution reaction (HER) co-catalyst, OWS was successfully realized over MnCo2O4@Pt@CNCOF, with consistent evolution of H2 and O2 in a 2:1 ratio.