Energy Transfer-Induced Photoelectrochemical Improvement from Porous Zeolitic Imidazolate Framework-Decorated BiVO 4 Photoelectrodes.

BiVO 4 , which is a representative photoanode material for photoelectrochemical water splitting, intrinsically restricts high conversion efficiency, owing to faster recombination, low electron mobility, and short electron diffusion length. While the photocurrent density of typical BiVO 4 corresponds to only 21.3% of the maximum photocurrent density (4.68 mA cm -2 ), decoration of the BiVO 4 photoanode with zeolitic imidazolate framework-67 (ZIF-67) exhibits a synergetic effect to raise the overall photocatalytic ability at the BiVO 4 surface region to a higher level via the energy-transfer process from BiVO 4 to ZIF-67. The hybrid ZIF-67/BiVO 4 photoanode follows two convenient photoelectrochemical pathways: 1) energy-transfer-induced water oxidation reaction in ZIF-67 and 2) water oxidation reaction by direct contact between the BiVO 4 surface and electrolytes. Compared to the moderate photocurrent density (≈1 mA cm -2 ) of single-layer BiVO 4 , the proposed ZIF-67/BiVO 4 photoanodes show a remarkably high photocurrent (2.25 mA cm -2 ) with high stability, despite the lack of hole scavengers in the electrolyte. Furthermore, the absorbed photon-to-current efficiency of the ZIF-67/BiVO 4 photoanode is ≈2.5 times greater than that of BiVO 4 . This work proposes a promising solution for efficient water oxidation that overcomes the intrinsic material limitations of BiVO 4 photoelectrodes by using energy transfer-induced photon recycling and the decoration of porous ZIFs.