Metal-organic framework derived Co3O4/TiO2 heterostructure nanoarrays for promote photoelectrochemical water splitting

In this work, we proposed a simple and new method to fabricate Metal-organic frameworks (MOFs) derived Co₃O₄ modified TiO₂ nanorods (NRs) photoelectrode by immersion and anneal treatment. The positively charged Co-MOF (ZIF-67) was adsorbed on the negatively charged TiO₂ NRs by electrostatic interaction, and then annealed in air to obtain the Co₃O₄/TiO₂ photoelectrodes. The photoelectrochemical (PEC) performance of the Co₃O₄/TiO₂ photoelectrodes has been significantly improved compared with the pure TiO₂, the best photocurrent density of Co₃O₄/TiO₂ photoelectrode could reach 1.04 mA/cm² (1.23 V vs RHE) which was almost 1.65 times than that of pure TiO₂. On the Co₃O₄/TiO₂ photoelectrodes, the significant improvement in PEC performance could be attributed to the constructed p-n heterostructure, which can promote charge transfer within the system and improve the efficiency of electron/hole separation. Meanwhile, under the action of the MOFs-derived Co₃O₄, the number of active sites increases significantly and visibly improve the photoresponse performance.