Rational tailoring of spin-polarized photoelectrode for magnetic-assisted overall water splitting

Photoelectrochemical (PEC) devices could play a significant role in efficient solar-to-fuel production for a sustainable economy. Herein, we report a significant enhancement of PEC water splitting via rational tailoring of ferromagnetic ordered oxygen evolution cocatalysts (OECs) iron-cobalt oxide on the Mo-doped BiVO 4 (Mo:BiVO 4 ) surface. The Fe 3+ and Co 2+ tend to form an optimal electron-filled arrangement, contributing to lower barriers for the oxygen evolution reaction (OER). Benefiting from the Fe/Co dual-site as the catalytic center, the prepared FeCoO x /Mo:BiVO 4 photoanode achieves 4.55 mA·cm −2 at 1.23 V vs reversible hydrogen electrode (RHE) with a lower starting potential for OER, outperforming the FeO x /Mo:BiVO 4 (2.71 mA·cm −2 ) and CoO x /Mo:BiVO 4 (3.48 mA·cm −2 ). Importantly, ferromagnetic iron-cobalt oxide as the spin polarizer can optimize the OER kinetics. Under spin-related effects, a magnetic stimulation strategy can further enhance the spin alignment. The corresponding photocurrent of FeCoO x /Mo:BiVO 4 is increased up to 5.15 mA·cm −2 under a magnetic field, with η Sep and η Trans reaching 89 % and 91 %, respectively. Specifically, the spin-polarization process will be helpful for the production of O(↓)O(↓)H intermediates, preferring to produce O 2 . Hence, this study provides a new pathway for designing highly efficient PEC water splitting systems on magnetic-assisted photoelectrodes.