Interfacial active-site-rich 0D Co3O4/1D TiO2 p-n heterojunction for enhanced photocatalytic hydrogen evolution

The hydrogen evolution activity of photocatalysts could be optimized by improving charge separation, light absorption capacity, and surface-active site number. In an attempt to engineer these critical factors in semiconductor photocatalytic processes, herein, we construct an active-site-rich 0D/1D Co3O4/TiO2 p-n heterojunction by growing p-type Co3O4 nanoparticles onto the surface of n-type TiO2 porous fibers. The in situ-generated porous outer walls formed over the surface of TiO2 fibers can increase the accessible active sites and enhance the light capture capacity. The optimal 0D/1D Co3O4/TiO2 heterojunction exhibits the excellent H2 evolving rate of 3.46 mmol g−1h−1 and considerably higher stability than its counterparts, including TiO2 fibers, 2D/1D and 3D/1D Co3O4/TiO2 hybrids. The main reason for this eminent photocatalytic performance was due to the synergistic effect of the porous outer-walls of the TiO2 nanofibers, favourable intimate interface between Co3O4 and TiO2, built-in electric field induded by p–n heterojunction and the cocatalytic effect of Co3O4, which can create more active sites and lead to rapid charge carrier migration. This study provides an important guideline for designing surface-engineered heterostructures in photocatalytic applications.