High-performance Bi₂S₃/ZnO photoanode enabled by interfacial engineering with oxyanion for efficient photoelectrochemical water oxidation

In the present contribution, we demonstrate that the sluggish kinetics of oxygen evolution reaction (OER) over the bismuth sulfide (Bi₂S₃) photoanode, which severely restricts its photoelectrochemical activity, is markedly accelerated by employing a sulfate-containing electrolyte. First-principle calculation points to the spontaneous adsorption of sulfate (SO₄²⁻) on Bi₂S₃ and its capacity of stabilizing the OER intermediates through hydrogen bonding, which is further reinforced by increasing the local density of states near the Fermi level of Bi₂S₃. Meanwhile, the electron transfer is also promoted to synergistically render the rate-determining step (from O* to OOH*) of OER over Bi₂S₃ kinetically facile. Last but not least, benefitting from such enhanced OER activity and efficient charge separation resulted from depositing Bi₂S₃ on the zinc oxide nanorods (ZnO NRs), forming a core–shell heterojunction, its photocurrent density achieves 8.61 mA·cm⁻² at 1.23 V_RHE, far surpassing those reported for additional Bi₂S₃-based and several state-of-the-art photoanodes in the literature and further exceeding their theoretical limit. The great promise of the Bi₂S₃/ZnO NRs is in view of such outperformance, the superior Faradaic yield of oxygen of more than ~ 80% and the outstanding half-cell applied bias photon-to-current efficiency of ~ 1% well corroborated.