Photocatalytic H2 Evolution from Ammonia Borane: Improvement of Charge Separation and Directional Charge Transmission.

Co/MII Fe layered double hydroxide (LDH) LDH photocatalysts have been designed from the aspect of employing stable half-filled Fe3+ to trap photogenerated electrons, adjusting the MII -O-Fe oxo-bridged structure to optimize the short-range directional charge transmission and intercalating oxometallate anions into the LDH to further improve light absorption along with electron-hole separation and non-noble metal Co NP loading and reduction to form a heterojunction. These LDH-based photocatalysts are employed for photocatalytic H2 evolution from ammonia borane in aqueous solution under visible light at 298 K. The photocatalytic H2 evolution activity is greatly improved through adjustment of the MII -O-Fe oxo-bridged structure and molybdate intercalation into the LDH. Turnover frequencies of up to 113.2 min-1 are achieved with Co/CoFe-Mo. Alongside the experimental results and materials characterization, capture experiments and in situ DRIFTS analysis are carried out to study the photocatalytic hydrogen production mechanism.