Photoelectrochemical (PEC) water splitting has been recognized as the most promising approach for directly converting solar energy into chemical energy, and substantial efforts have been made to develop a highly efficient and low-cost photoanode for enhancement of PEC water splitting efficiency due to sluggish water oxidation reaction kinetics. A ternary NiFePB-modified ZnO/BiVO4 heterojunction photoanode was simply assembled by low-temperature hydrothermal, metal–organic decomposition and electrodeposition methods to improve the water splitting efficiency; its photocurrent density for water oxidation reached 1.66 mA cm−2 at 1.23 V (vs. RHE); in comparison, that of ZnO is only 0.4 mA cm−2. The onset potential manifests a cathodic shift of ∼283 mV compared to ZnO. The IPCE and the ABPE respectively are 3.1 and 6.4 times those of ZnO, respectively. This improvement is ascribed to the efficient separation of photogenerated electrons and holes by the formation of a heterojunction between ZnO and BiVO4 and the enhancement in the oxygen evolution reaction kinetics by the decoration of the co-catalyst NiFePB as a hole acceptor.
Yaping Li,Xianglin Sun,Yiming Tang,Yun Hau Ng,Lintao Li,Feng Jiang,Jing Wang,Weirui Chen,Laisheng Li
The coral-like BiVO 4 was successfully constructed on ZnO nanorods grown on FTO substrates to reveal exceptional photoinduced charge migration kinetics as well as the underlying photoelectrocatalytic degradation process. The orderly ZnO nanorods array accelerated the separation of photogenerated carriers, while the three-dimensional coral structure of ZnO/BiVO 4 nanocomposite increased the efficiency of light absorption and mass transfer, thus improving the photoelectrochemical properties. Fine interfacial contact between ZnO and BiVO4 led to the optimized photoelectrochemical performance with a photocurrent density of 0.29 mA/cm2 at 0 V vs . Ag/AgCl under visible light illumination (λ ≧ 420 nm), which was 3.2 times, 1.6 times of that of pristine ZnO and BiVO4. Moreover, the photoelectrocatalytic degradation efficiency of tetracycline from the ZnO/BiVO4 nanocomposite on was c. a. 84.5% and the main degradation paths were analyzed by LC-MS. Radical scavengers were employed to evaluate the capability to produce •O 2 − and •OH active species upon visible light illumination. This study elucidated the reaction mechanisms of the ZnO/BiVO4 nanocomposite during the photoelectrocatalytic degradation process.
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