ZIF-67-derived CoP as a single photocatalyst exhibited extremely excellent H2 evolution performance in Eosin Y sensitization system. Specifically, both Co3O4 and CoP polyhedron can be derived by ZIF-67 as a precursor in different atmosphere. Interestingly, ZIF-67-derived Co3O4 is a typical p-type semiconductor but CoP is an n-type semiconductor. Therefore, one-step construction of Co3O4@CoP p-n heterojunction was successfully implemented firstly in this work, that is, ZIF-67 polyhedron was transformed into Co3O4@CoP polyhedron that Co3O4 co-arranged with CoP species. More importantly, the ZIF-67-derived Co3O4@CoP p-n heterojunction photocatalyst exhibits more excellent photoctalytic water splitting properties than ZIF-67-derived CoP and Co3O4 as well as previous-best catalysts under identical conditions because of multi-action mechanism synergy. Additionally, the action mechanism about metal phosphides in H2 evolution reaction is revealed more thoroughly by the assistance of DFT and Zeta potential analysis

The design and construction of hierarchical CoP/ZnCdS/Co3O4 quantum dots (QDs) (800>40>4.5 nm) bi-heterostructure cages as an ultrahigh-performance photocatalyst for hydrogen evolution with visible light is investigated. Three excellent photoactive materials that ZnCdS solid solution, high-conductivity CoP and high-efficiency Co3O4 QDs were integrated into a all-in-one bi-heterostructure cage architecture. Presence of the two high-efficiency electron-transfer pathways in CoP/ZnCdS/Co3O4 QDs can seriously facilitate the separation and migration of light-induced electrons while the unique structure also can offer large reaction surface and expose abundant active sites for photocatalytic hydrogen evolution reaction. Because of the distinctively compositional and structural merits, the hierarchical CoP/ZnCdS/Co3O4 QDs bi-heterostructure cages without introducing any cocatalysts exhibit ultrahigh activity and favorable stability for generation of high-purity hydrogen under visible light irradiation.