Single‐Source Bismuth (Transition Metal) Polyoxovanadate Precursors for the Scalable Synthesis of Doped BiVO₄ Photoanodes

Abstract

Single‐source precursors are used to produce nanostructured BiVO4 photoanodes for water oxidation in a straightforward and scalable drop‐casting synthetic process. Polyoxometallate precursors, which contain both Bi and V, are produced in a one‐step reaction from commercially available starting materials. Simple annealing of the molecular precursor produces nanocrystalline BiVO4 films. The precursor can be designed to incorporate a third metal (Co, Ni, Cu, or Zn), enabling the direct formation of doped BiVO4 films. In particular, the Co‐ and Zn‐doped photoanodes show promise for photoelectrochemical water oxidation, with photocurrent densities >1 mA cm−2 at 1.23 V vs reversible hydrogen electrode (RHE). Using this simple synthetic process, a 300 cm2 Co‐BiVO4 photoanode is produced, which generates a photocurrent of up to 67 mA at 1.23 V vs RHE and demonstrates the scalability of this approach.

Beyond Charge Balance: Counter‐Cations in Polyoxometalate Chemistry

“…In an earlier study, Streb and colleagues used a similar approach to stabilize the elusive vanadium(V)‐based Keggin anion [V 13 O 40 ] 15− with Bi 3+ cations, also providing a molecular mimic of technologically important solid‐state bismuth vanadium oxides . The authors reported the self‐assembly of the first molecular Bi‐V‐oxide cluster H 3 [{Bi(dmso) 3 } 4 V 13 O 40 ] (= {Bi 4 V 13 } ) by reaction of Bi 3+ with [H 3 V 10 O 28 ] 3− in dimethyl sulfoxide (DMSO) .…”

“…In an earlier study, Streb and colleagues used a similar approach to stabilize the elusive vanadium(V)-based Keggin anion [V 13 O 40 ] 15À with Bi 3+ cations, also providing a molecular mimic of technologically important solid-state bismuth vanadium oxides. [71] The authors reported the self-assembly of the first molecular Bi-V-oxide cluster H 3 [68] The rare e-Keggin isomer [35,72] of {Bi 4 V 13 } is stabilized by four Bi 3+ cations coordinated to the cluster surface ( Figure 2), which in turn are coordinated by three terminal DMSO ligands. When considering the requirements to stabilize [e-V 13 O 40 ] 15À , it is apparent that structural/ coordinative stabilization is required in addition to (cationic) electrostatic stabilization.…”

Demonstration of a 50 cm2 BiVO4 tandem photoelectrochemical-photovoltaic water splitting device

“…They showed that simply increasing the electrode area decreases the photocurrent by a factor of $5. 31 These types of losses have been observed elsewhere in the scale up of metal oxide photoanodes. 32 However, no detailed analysis of the underlying reasons for the lower photocurrent densities for the large area photoanodes (25 and 300 cm 2 ) as compared to the smaller area (1 cm 2 ) was made.…”

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

“…[312][313][314] Vanadium-containing polyoxometalates have been used in dye-sensitized solar cells via as cosensitizers 84 and as precursors for solar conversion photoanode synthesis such as BiVO 4 . 315 The inclusion of vanadium in polyoxometalates can improve the battery performance. 316 ] is demonstrated to be useful in lithium-ion battery cathode, since the lithium ion diffusion in the polyoxometalate is fast.…”