Engineering a hetero-MOF-derived TiO 2 –Co 3 O 4 heterojunction decorated with nickel nanoparticles for enhanced photocatalytic activity even in pure water

A highly porous ternary TiO 2 /Co 3 O 4 /Ni photocatalyst is successfully constructed from a hetero-metal organic framework (H-MOF) template and via a facile photoreduction method. The photocatalytic H 2 production coupled with the formation of H 2 O 2 on TiO 2 is improved by co-loading an oxidation promoter (Co 3 O 4 ) and a reduction promoter (Ni) owing to the following factors: porous Co 3 O 4 promotes the optical-response ability and surface water oxidation kinetics of TiO 2 , 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 TiO 2 /5at%Co 3 O 4 /0.5at%Ni heterostructure exhibits a hydrogen production activity 8.7 times higher than that of pure TiO 2 , and demonstrates obvious photocatalytic hydrogen evolution even in pure water, with stoichiometric H 2 O 2 production. This work will provide insights into the design and synthesis of noble metal-free dual cocatalyst systems for efficient charge separation and transfer.