TiO2@ Layered Double Hydroxide Core-Shell Nanospheres with Largely Enhanced Photocatalytic Activity Toward O-2 Generation

TiO2@CoAl-layered double hydroxide (LDH) core-shell nanospheres are fabricated via hydrothermal synthesis of TiO2 hollow nanospheres followed by in situ growth of CoAl-LDH shell, which exhibit an extraordinarily high photocatalytic activity toward oxygen evolution from water oxidation. The O-2 generation rates of 2.34 and 2.24 mmol h(-1) g(-1) are achieved under full sunlight (>200 nm) and visible light (>420 nm), respectively, which are among the highest photocatalytic activities for oxygen production to date. The reason is attributed to the desirable incorporation of visible-light-active LDH shell with UV light-responsive TiO2 core for promoted solar energy utilization. Most importantly, the combined experimental results and computational simulations reveal that the strong donor-acceptor coupling and suitable band matching between TiO2 core and LDH shell facilitate the separation of photoinduced electron-hole pairs, accounting for the highly efficient photocatalytic performance. Therefore, this work provides a facile and cost-effective strategy for the design and fabrication of hierarchical semiconductor materials, which can be applied as photocatalyst toward water splitting and solar energy conversion.