Enabling Solar Water Oxidation by BiVO₄ Photoanodes in Basic Media

Abstract

Titanium dioxide (TiO2) deposited by atomic layer deposition (ALD) has been the most commonly used protection layer to enhance chemical and photoelectrochemical stabilities of photoelectrodes. In this study, we report a new electrochemical deposition method that can place a thin, conformal TiO2 coating layer on a photoelectrode. This method takes <1 min and may serve as a practical alternative to ALD for the deposition of a TiO2 layer. The uniform quality of the TiO2 protection layer was confirmed by demonstrating the chemical stability of the BiVO4/TiO2 electrode in strongly basic media (pH 12 and 13) where BiVO4 readily dissolves. More importantly, the high-quality TiO2 protection layer made it possible to comparatively investigate photoelectrochemical properties and stabilities of the BiVO4 and BiVO4/TiO2 electrodes, which was critical to elucidate the effect that the chemical instability of BiVO4 in basic media has on the rate of photocorrosion. Systematic photoelectrochemical studies for sulfite oxidation and water oxidation provided a coherent understanding of how the interplay among the relative rates of interfacial charge transfer, surface recombination, and photocorrosion affects the photocurrent generation and photostability of BiVO4. On the basis of this understanding, stable photocurrent generation for water oxidation could be achieved at pH 12 over 20 h using a BiVO4/TiO2/FeOOH/NiOOH electrode where FeOOH/NiOOH served as oxygen evolution catalyst. The results and discussion contained in this study provide new insights into the understanding of photocurrent decay caused by photocorrosion involving dissolution, enabling the development of effective strategies to achieve stable photocurrent generation.

Resistance-based analysis of limiting interfaces in multilayer water splitting photocathodes by impedance spectroscopy

“…Amongst these promising semiconductors are Cu 2 O, 1,2 CuO, 3 Si, [4][5][6][7] III-V semiconductors, 8,9 Cu 2 BaSnS 4 , 10 Cu 2 ZnSnS 4 , 11 and BiVO 4 . 12,13 Additionally, semiconducting buffer layers such as Ga 2 O 3 (ref. 2 and 14) or CdS 3 can be inserted between the photoabsorber and protection layers to increase the built-in voltage, the charge separation and the overall device efficiency.…”

Bismuth Vanadate/Bilirubin Oxidase Photo(bio)electrochemical Cells for Unbiased, Light‐Triggered Electrical Power Generation

“…Notably, BpBOD produced a poor bioelectrocatalytic current if it was entrapped in the polydopamine matrix, whereas the DET method based on pyrenebetaine exhibited much better results. In recent years, photoanodes based on BiVO 4 have shown long‐term stability . These findings encourage further development of applications to make use of environmentally friendly, photoactivated PBECs for the generation of electrical energy.…”

Recent Advances and Emerging Trends in Photo‐Electrochemical Solar Energy Conversion

“…[79][80][81][82] Several thorough review and perspective articles on hematite have been published recently, and the interested reader is referred to these articles for the history and advancements with iron oxide photoanodes. [88][89][90][91][92][93] Pihosh et al have demonstrated impressively high photocurrents using a socalled extremely thin absorber approach, where a thin BiVO 4 layer was coated on WO 3 nanowires, obtaining 6.7 mA cm −2 at an applied bias of 1.23 V versus RHE, which corresponds to about 90% of the theoretical maximum photocurrent value for this material (Figure 5). A major step forward was made with this material when a spray-pyrolysis synthesis method was reported that reproducibly gave currents in the mA cm −2 range, [87] kicking off a flurry of investigation by other researchers.…”

“…Also in the 2000s, interest was gaining in a new multinary oxide material, BiVO 4 , as the bandgap was reasonably small for an oxide (≈2.4 eV), and it was composed of earth‐abundant elements. A major step forward was made with this material when a spray‐pyrolysis synthesis method was reported that reproducibly gave currents in the mA cm −2 range, kicking off a flurry of investigation by other researchers . Pihosh et al have demonstrated impressively high photocurrents using a so‐called extremely thin absorber approach, where a thin BiVO 4 layer was coated on WO 3 nanowires, obtaining 6.7 mA cm −2 at an applied bias of 1.23 V versus RHE, which corresponds to about 90% of the theoretical maximum photocurrent value for this material ( Figure 5 ).…”