Highly Efficient Photoelectrochemical Water Splitting with an Immobilized Molecular Co4 O4 Cubane Catalyst.

Molecular Co4 O4 cubane water oxidation catalysts were combined with BiVO4 electrodes for photoelectrochemical (PEC) water splitting. The results show that tuning the substituent groups on cobalt cubane allows the PEC properties of the final molecular catalyst/BiVO4 hybrid photoanodes to be tailored. Upon loading a new cubane complex featuring alkoxy carboxylato bridging ligands (1 h) on BiVO4 , an AM 1.5G photocurrent density of 5 mA cm-2 at 1.23 V vs. RHE for water oxidation was obtained, the highest photocurrent for undoped BiVO4 photoanodes. A high solar-energy conversion efficiency of 1.84 % was obtained for the integrated photoanode, a sixfold enhancement over that of unmodified BiVO4 . These results and the high surface charge separation efficiency support the role of surface-modified molecular catalysts in improving PEC performance and demonstrate the potential of molecule/semiconductor hybrids for efficient artificial photosynthesis.