Differentiating the role of Ni and Fe in NiFeOx co-catalyzed BiVO4 photoanode for water oxidation
Michael Gunawan, Matthew Priest, Denny Gunawan, Shuai Nie, Adhi Satriyatama, Jitraporn Vongsvivut, Ziv Hameiri, Qingran Zhang, Shujie Zhou, Rose Amal
Abstract
Photoelectrochemical (PEC) water splitting is a promising technology for green hydrogen production. However, severe charge recombination at the photoanode has impeded its advancement. Incorporating co-catalyst on bismuth vanadate (BiVO 4 , BVO) photoanode could enhance the charge transfer efficiency and accelerate the surface reaction kinetics, which are two key challenges in the PEC system. Herein, NiFeO x co-catalyst is deposited on BVO (NiFeO x -BVO), enhancing the performance to 3.3 times (3.57 mA cm −2 at 1.23 V vs. RHE) in comparison to the pristine BVO. A systematic analysis has been engaged to unravel the individual roles of Ni and Fe in enhancing the PEC performance of NiFeO x -BVO. While the Ni enhances the charge transfer of BVO, the Fe is found to accelerate the water oxidation kinetics at the surface of photoanode. Working synergistically, the NiFeO x enhanced bulk (72.2 %) and surface (76.4 %) charge transfer efficiency compared to the pristine BVO (55.1 % and 30.5 %, respectively), measured at 1.23 V vs. RHE. This work provides important insights into rationally designing the cocatalysts for efficient PEC water splitting.