Stable Cocatalyst‐Free BiVO₄ Photoanodes with Passivated Surface States for Photocorrosion Inhibition

Abstract

Improving charge transport and reducing bulk/ surface recombination can increase the activity and stability of BiVO 4 for water oxidation. Herein we demonstrate that the photoelectrochemical (PEC) performance of BiVO 4 can be significantly improved by potentiostatic photopolarization. The resulting cocatalyst-free BiVO 4 photoanode exhibited a record-high photocurrent of 4.60 mA cm À2 at 1.23 V RHE with an outstanding onset potential of 0.23 V RHE in borate buffer without a sacrificial agent under AM 1.5G illumination. The most striking characteristic was a strong "self-healing" property of the photoanode, with photostability observed over 100 h under intermittent testing. The synergistic effects of the generated oxygen vacancies and the passivated surface states at the semiconductor-electrolyte interface as a result of potentiostatic photopolarization reduced the substantial carrier recombination and enhanced the water oxidation kinetics, further inhibiting photocorrosion.

Photo‐driven Oxygen Vacancies Extends Charge Carrier Lifetime for Efficient Solar Water Splitting

“…The improved PEC performance is attained, and the negative shift of onset potential, approximately 0.1 V RHE , is observed in buffer electrolyte (Supporting Information, Figure S1). These results are agreed well with the previous work on the photo‐polarized BiVO 4 samples, in which a typical surface passivation benefits the PEC activity of the photoanode [28] . The surface separation efficiency of WO 3 and PC‐WO 3 was further evaluated as a hole scavenger of Na 2 SO 3 was added to the Na 2 SO 4 electrolyte (Figure S2).…”

Photo‐driven Oxygen Vacancies Extends Charge Carrier Lifetime for Efficient Solar Water Splitting

“…These results are agreed well with the previous work on the photopolarized BiVO 4 samples,i nw hich at ypical surface passivation benefits the PEC activity of the photoanode. [28] The surface separation efficiency of WO 3 and PC-WO 3 was further evaluated as ah ole scavenger of Na 2 SO 3 was added to the Na 2 SO 4 electrolyte (Figure S2). Theh igh charge transfer efficiency obtained on PC-WO 3 electrode manifests the improved surface water oxidation kinetics,b er eason of the increased oxygen vacancies at the surface as literatures reported.…”

“…by electrochemically induced generation of low valent metal species [26, 27] . Our more recent work propounded a light‐induced treatment through potentiostatic polarization exposure to AM 1.5G solar light, which near‐completely suppressed the surface recombination and boosted the PEC activity of BiVO 4 photoanodes [28] . During the illumination, the electron and hole would be initiated and located at the motivated status.…”

“…[26,27] Our more recent work propounded alightinduced treatment through potentiostatic polarization exposure to AM 1.5G solar light, which near-completely suppressed the surface recombination and boosted the PEC activity of BiVO 4 photoanodes. [28] During the illumination, the electron and hole would be initiated and located at the motivated status.The progress in the activated electrodes how to influence the carrier lifetime,isstill in early infancy, which encourages us to identify the research to investigate general approach for improving the charge transfer efficiency at the interface.…”

Recent progress of bismuth vanadate-based photoelectrocatalytic water splitting

“…但是, [61] . 另一方面, Gao和Wang [56] ; (b) FeCoO x /BiVO 4 与CoO x /BiVO 4 光阳极在AM 1.5 G辐 射下与1.23 V vs. RHE偏压下的计时光电流密度曲线 [60] ; (c) FeCoO x /BiVO 4 、CoO x /BiVO 4 与BiVO 4 光阳极的催化效率与外加电压曲线 [60] ; (d) B-BiVO 4 光阳极示意图 [61] ; (e) B-BiVO 4 与BiVO 4 光阳极的J-V曲线 [60] ; (b) time dependent photocurrent density curves at 1.23 V versus RHE under AM 1.5 G illumination of the FeCoO x /BiVO 4 and CoO x /BiVO 4 photoanodes [60] ; (c) catalytic efficiency versus applied potential curves of the FeCoO x /BiVO 4 , CoO x /BiVO 4 and BiVO 4 photoanodes [60] ; (d) schematic diagram showing the B-BiVO 4 photoanode preparation [61] ; (e) J-V curves of BiVO 4 and B-BiVO 4 photoanodes [61] 进 展…”