(040)‐Crystal Facet Engineering of BiVO₄ Plate Photoanodes for Solar Fuel Production

Abstract

mobility and fast charge recombination, which result in limitations during practical application. Because the solar light conversion effi ciency ( η ) [ 15 ] is directly proportional to the product of the solar light absorption effi ciency ( η abs ), charge separation effi ciency ( η sep ), and surface charge transfer effi ciency ( η trans ). The decoration of the cocatalyst [ 16 ] and the introduction of porosity to increase surface area [ 17 ] have been studied for practical usage of PEC with increased η abs , η sep , and η trans . Specifically, recent developments in the fully integrated nanowire-based heterostructure [ 18,19 ] and the introduction of a dual-layer oxidation cocatalyst [ 20 ] into porous BiVO 4 have been reported for practical solar fuel production with good η abs , η sep , and η tran .However, the typical PEC performance of a pristine BiVO 4 photoanode to produce solar fuel products is not impressive because it suffers from inherent drawbacks. The development and design of BiVO 4 microcrystals have been highlighted to produce solar fuel products by introducing photocatalytic crystal facet engineering and cocatalyst, [20][21][22] and the breakthrough for enhancing solar light conversion effi ciency has not been suggested previously for a pristine BiVO 4 photoanode.Here, a (040)-crystal facet engineered BiVO 4 ((040)-BVO) plate photoanode has been investigated to produce solar fuel products as an artifi cial photosynthesis with highly enhanced PEC performance via a crystal facet engineering approach that is based on reports by Cheng and co-workers [ 23,24 ] and Li and co-workers. [ 11,21,22 ] We demonstrate the higher PEC performance caused by higher effi cient η sep and η tran of the BVO thin fi lm with selectively exposed (040) crystal facet. Because the (040) facet-manipulated BiVO 4 plate photoanode has not been previously studied, our designed model demonstrates the signifi cance of the interfacial electron transport reaction between the {010} plane and the electrolyte with η sep and η tran , resulting in the highest PEC performance. The results of this study may provide the most viable strategy for designing an effi cient BiVO 4 photoanode for enhanced solar fuel production. Results and DiscussionA (040)-crystal facet engineered BiVO 4 plate photoanode ((040)-BVO) was hydrothermally synthesized via a seed layer approach A (040)-crystal facet engineered BiVO 4 ((040)-BVO) photoanode is investigated for solar fuel production. The (040)-BVO photoanode is favorable for improved charge carrier mobility and high photocatalytic active sites for solar light energy conversion. This crystal facet design of the (040)-BVO photoanode leads to an increase in the energy conversion effi ciency for solar fuel production and an enhancement of the oxygen evolution rate. The photocurrent density of the (040)-BVO photoanode is determined to be 0.94 mA cm −2 under AM 1.5 G illumination and produces 42.1% of the absorbed photon-to-current conversion effi ciency at 1.23 V (vs RHE, reversible hydrogen electrode). ...

Promoting Photogenerated Holes Utilization in Pore‐Rich WO3 Ultrathin Nanosheets for Efficient Oxygen‐Evolving Photoanode

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rate (≈12 cm 2 V −1 s −1 ) compared to TiO 2 (0.5 cm 2 V −1 s −1 ), a robust hole migration length (≈150 nm) relative to Fe 2 O 3 (2-4 nm), and attractive photostability. [15][16][17][18][19] Considering the specific WO 3 , recent studies have revealed that nanosheets exposed with {001} facets show better catalytic activity than the other facets due to the highest oxygen atom density. In this regard, with an aim to further breakthroughs for pursuing excellent energy conversion performance in high-potential WO 3 photoanode, integrated dismantling aforesaid restricting factors are greatly imperative.

As such, tailoring crystal facets is a conventional strategy for optimizing the catalytic performance in the case of various semiconductor materials because heterogeneous reactivity depends strongly on the surface atomic configuration and bonding environment that can be altered by controlling crystalline facets.

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“…[15][16][17][18][19] Considering the specific WO 3 , recent studies have revealed that nanosheets exposed with {001} facets show better catalytic activity than the other facets due to the highest oxygen atom density. [15][16][17][18][19] Considering the specific WO 3 , recent studies have revealed that nanosheets exposed with {001} facets show better catalytic activity than the other facets due to the highest oxygen atom density.…”

Polyhedral 30‐Faceted BiVO4 Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity

“…[20] Varieties of morphological BiVO 4 , which are generally enclosed by lowindex {111}, {110}, or {100} planes, were formed through control of the synthetic methods and experimental conditions. [21][22][23] The photocatalytic behavior of BiVO 4 is highly dependent on its surface structure, in which photogenerated electrons and holes can be preferentially separated and accumulated on {010} and {110} facets, respectively, via the driving force created by the different band energies of the two facets. [24,25] Herein, we report the synthesis unprecedented 30-faceted BiVO 4 polyhedra predominantly surrounded by high-index {132}, {321}, and {121} facets.…”

Nanowire Array Structures for Photocatalytic Energy Conversion and Utilization: A Review of Design Concepts, Assembly and Integration, and Function Enabling

“…Designing photocatalyst systems of multiple scales to overcome these competing effects has been proposed and successfully demonstrated. [17,57] For example, it has been reported that electron and hole transfer occurs on different crystallographic planes of both rutile and anatase TiO 2 microcrystal. [47] Crystallinity and defects: Crystallinity is considered as a complex factor for reactivity of photocatalyst.…”