Engineering a hetero-MOF-derived TiO2–Co3O4 heterojunction decorated with nickel nanoparticles for enhanced photocatalytic activity even in pure water

Abstract

A highly porous ternary TiO₂/Co₃O₄/Ni photocatalyst is successfully constructed from a hetero-metal organic framework (H-MOF) template and via a facile photoreduction method. The photocatalytic H₂ production coupled with the formation of H₂O₂ on TiO₂ is improved by co-loading an oxidation promoter (Co₃O₄) and a reduction promoter (Ni) owing to the following factors: porous Co₃O₄ promotes the optical-response ability and surface water oxidation kinetics of TiO₂, and in situ photo-deposited Ni facilitates the transport and utilization efficiency of photo-excited electrons. Owing to the synergy of the improved specific surface area and improved separation as well as utilization of photogenerated charge carriers, the optimal ternary TiO₂/5at%Co₃O₄/0.5at%Ni heterostructure exhibits a hydrogen production activity 8.7 times higher than that of pure TiO₂, and demonstrates obvious photocatalytic hydrogen evolution even in pure water, with stoichiometric H₂O₂ production. This work will provide insights into the design and synthesis of noble metal-free dual cocatalyst systems for efficient charge separation and transfer.