Anthraquinone-based polymer modified BiVO₄ photoanode with strong electron-withdrawing functional groups for boasting...

The photoelectrochemical (PEC) performance ofBiVO₄ is limited by sluggish water oxidation kinetics and severe carrier recombination. Herein, a novel high-performance BiVO₄/NiFe-NOAQ photoanode is prepared by a simple one-step hydrothermal method, using BiVO₄ and 1-Nitroanthraquinone (NOAQ) as raw materials. The BiVO₄/NiFe-NOAQ photoanode has an excellent photocurrent density of 5.675 mA cm^-2 at 1.23 V_RHE, which is 3.35 times higher than that of the pure BiVO₄ (1.693 mA cm^-2) photoanode. The BiVO₄/NiFe-NOAQ shows a significant improvement in charge separation efficiency (86.12 %) and charge injection efficiency (87.86 %). The improvement is ascribable to the NiFe-NOAQ form a type II heterojunction with BiVO₄ to inhibit carrier recombination. More importantly, the kinetic isotope experiment suggests that the proton-coupled electron transfer (PCET) process can enhance the charge transfer of BiVO₄/NiFe-NOAQ. The contact angle measurements show that modifying functional groups enhanced the hydrophilicity of BiVO₄/NiFe-NOAQ, which can further accelerate the PCET process. The XPS and PL results as well as the tauc plot indicate that the strong electron-withdrawing ability of -NO₂ which can promote the extension of π conjugation, results in more π electron delocalization and produces more efficient active sites, thus achieving efficient photoelectrochemical water oxidation.