New BiVO₄ Dual Photoanodes with Enriched Oxygen Vacancies for Efficient Solar‐Driven Water Splitting

Abstract

Bismuth vanadate (BiVO ) is a promising photoanode material for photoelectrochemical (PEC) water splitting. However, owing to the short carrier diffusion length, the trade-off between sufficient light absorption and efficient charge separation often leads to poor PEC performance. Herein, a new electrodeposition process is developed to prepare bismuth oxide precursor films, which can be converted to transparent BiVO films with well-controlled oxygen vacancies via a mild thermal treatment process. The optimized BiVO film exhibits an excellent back illumination charge separation efficiency mainly due to the presence of enriched oxygen vacancies which act as shallow donors. By loading FeOOH/NiOOH as the cocatalysts, the BiVO dual photoanodes exhibit a remarkable and highly stable photocurrent density of 5.87 mA cm at 1.23 V versus the reversible hydrogen electrode under AM 1.5 G illumination. An artificial leaf composed of the BiVO /FeOOH/NiOOH dual photoanodes and a single sealed perovskite solar cell delivers a solar-to-hydrogen conversion efficiency as high as 6.5% for unbiased water splitting.

Freeing the Polarons to Facilitate Charge Transport in BiVO4 from Oxygen Vacancies with an Oxidative 2D Precursor

“…To further confirm our hypothesis, more detailed characterizations are presented below with respect to the oxygen vacancy abundance in IO 3 _BiVO 4 and BiVO 4 . X‐ray photoelectron spectroscopy (XPS) is widely used to ascertain the existence of oxygen vacancies . The high binding energy component of O 1s peak has been frequently assigned to oxygen vacancies.…”

Dimension‐Matched Zinc Phthalocyanine/BiVO4 Ultrathin Nanocomposites for CO2 Reduction as Efficient Wide‐Visible‐Light‐Driven Photocatalysts via a Cascade Charge Transfer

“…[1,2] BiVO 4 as apromising photocatalyst has attracted ag reat deal of attention owing to its environmental friendliness,chemical stability,and narrow band-gap alignment. [6,7] Generally speaking, the granular morphology of BiVO 4 is one of the reasons for its poor charge separation. Furthermore,t he photocatalytic activity of BiVO 4 is also unsatisfactory owing to the sluggish charge separation, the limited visible-light utilization, and the low efficiency of charge-induced reactions.…”

Stepping towards Solar Water Splitting: Recent Progress in Bismuth Vanadate Photoanodes

“…Wang et al . reported a new electrodeposition process to prepare BiO x precursor films, followed by conversion to transparent BiVO 4 films with well‐controlled O v via a mild thermal treatment process (Figure c) . These O v synergistically increased the carrier density, photon absorption and electronic conductivity, leading to enhanced charge separation efficiency (Figure d and 10e).…”