Atomic Layer Deposition of Bismuth Vanadate Core–Shell Nanowire Photoanodes

Abstract

Bismuth vanadate (BVO) is a promising metal oxide semiconductor for photoelectrochemical water oxidation. In this study, BVO was deposited using atomic layer deposition (ALD) of alternating films of bismuth and vanadium oxides. A novel Bi-alkoxide precursor was used to enable precise control of stoichiometry along the spectrum of Bi-rich to V-rich compositions, and phase-pure monoclinic BVO films were obtained after postannealing. A planar photoanode composed of an undoped 41.8 nm BVO thin-film electrode with an ALD SnO2 buffer layer produced a photocurrent density of 2.24 mA/cm2 at 1.23 V vs RHE. ALD was used to conformally coat BVO and SnO2 on a ZnO nanowire template to produce core–shell photoanodes exhibiting a 30% increase in photocurrent density (2.9 mA/cm2 at 1.23 V) relative to planar control electrodes. This is the highest photocurrent reported to date for an ALD-deposited photoanode, and provides a pathway toward rational design of 3-D nanostructured photoelectrode architectures.

High‐Performance Zinc Tin Oxide TFTs with Active Layers Deposited by Atomic Layer Deposition

“…Ternary oxides can also be deposited using ALD by combining two binary processes into a supercycle. [17][18][19] A supercycle combines and repeats the different binary ALD processes to deposit a multi-component film with the desired composition, as shown in Figure 1a.…”

Planar and Nanostructured n‐Si/Metal‐Oxide/WO3/BiVO4 Monolithic Tandem Devices for Unassisted Solar Water Splitting

“…As is expected, and has been widely reported, these results highlight the benefit of forming nanostructured heterojunctions to improve the PEC performance of BiVO 4 photoanodes. [ 28,30,32,37,38,43,44 ]…”

Atomic Layer Deposition for the Photoelectrochemical Applications

“…c‐f) Reproduced with permission. [ 32 ] Copyright 2019, American Chemical Society. g) SEM image of the top view of the nanotubes that were coated by ATO and BiVO 4 using ALD.…”

“…ALD has been used for the deposition onto the nanowire substrate. [ 32,33 ] With bismuth vanadate, two metal precursors need to be introduced. BiVO 4 is produced by the introduction of Bi‐ and V‐ precursors cycles following thermal annealing, to induce crystallization of Bi‐ and V‐ layers (Figure 3c–f).…”

“…For example, SnO 2 was used to block hole injection from ZnO to BiVO 4 , in this way preventing hole accumulation at the semiconductor/electrolyte interface. [ 32,33 ] NiOOH has been frequently applied to n‐Si based photoanodes as a protection layer and OER catalyst. However, the energy level alignment at heterojunction is far from optimal.…”