Constructing Co(3)O(4)/La(2)Ti(2)O(7) p-n Heterojunction for the Enhancement of Photocatalytic Hydrogen Evolution

Layered perovskite-type semiconductor La(2)Ti(2)O(7) has attracted lots of attention in photocatalytic hydrogen evolution, due to the suitable energy band position for water splitting, high specific surface area, and excellent physicochemical stability. However, the narrow light absorption range and the low separation efficiency of photogenerated carriers limit its photocatalytic activity. Herein, plate-like La(2)Ti(2)O(7) with uniform crystal morphology was synthesized in molten NaCl salt. A p-n heterojunction was then constructed through the in situ hydrothermal growth of p-type Co(3)O(4) nanoparticles on the surface of n-type plate-like La(2)Ti(2)O(7). The effects of Co(3)O(4) loading on photocatalytic hydrogen evolution performance were investigated in detail. The results demonstrate that composite Co(3)O(4)/La(2)Ti(2)O(7) possesses much better photocatalytic activity than the pure component. The composite photocatalyst with 1 wt% Co(3)O(4) exhibits the highest hydrogen evolution rate of 79.73 μmol·g(−1)·h(−1) and a good cycling stability. The photoelectrochemistry characterizations illustrate that the improvement of photocatalytic activity is mainly attributed to both the enhanced light absorption from the Co(3)O(4) ornament and the rapid separation of photogenerated electron-hole pairs driven by the built-in electric field close to the p-n heterojunction. The results may provide further insights into the design of high-efficiency La(2)Ti(2)O(7)-based heterojunctions for photocatalytic hydrogen evolution.