Bendable BiVO₄-Based Photoanodes on a Metal Substrate Realized through Template Engineering for Photoelectrochemical Water Splitting

Abstract

Unlike planar photoelectrodes, bendable and malleable photoelectrodes extend their application to mechanical flexibility beyond conventional rigid structures, which have garnered new attention in the field of photoelectrochemical water splitting. A bendable metal (Hastelloy), which has both bendability and compatibility with various oxide layers, allows high-temperature processes for crystallization; therefore it is far superior as a substrate than a conventional flexible polymer. In this study, we fabricate bendable BiVO4 crystalline thin films on the metal substrates by employing template layers (SrRuO3/SrTiO3) to reduce the structural misfits between BiVO4 and the substrate. The crystallinities were verified through X-ray diffraction and transmission electron microscopy, and photocatalytic performances were examined. The crystallinity of BiVO4 was significantly improved by utilizing similar lattice constants and affinities between BiVO4 and the oxide template layers. We also formed a type II heterojunction by adding a WO3 layer which complements the charge separation and charge transfer as a photoanode. The photocurrent densities of tensile-bent BiVO4/WO3 thin films with a bending radius of 10 mm are comparable to those of pristine BiVO4/WO3 thin film in various aqueous electrolytes. Moreover, photostability tests showed that the tensile-bent crystalline photoanodes retained 90% of their initial photocurrent density after 24 h, which proved their exceptional durability. Our work demonstrates that the bendable photoelectrodes with crystallinity hold great potential in terms of device structure for solar-driven water splitting.

Controlled Band Offsets in Ultrathin Hematite for Enhancing the Photoelectrochemical Water Splitting Performance of Heterostructured Photoanodes

“…0.3 V vs the RHE) originates from the trapped photogenerated charges caused by light exposure. 40 We also measured the photocurrent density and the transient curve of 10 nm-thick Fe 2 O 3 with and without a hole scavenger. The Fe 2 O 3 (10 nm)/ BVO/WO 3 /FTO photoanode measured with the hole scavenger shows almost a twice higher photocurrent density compared with the photoanode without the hole scavenger.…”

“…The photocurrent increase before the onset potential (0 ∼ ca. 0.3 V vs the RHE) originates from the trapped photogenerated charges caused by light exposure . We also measured the photocurrent density and the transient curve of 10 nm-thick Fe 2 O 3 with and without a hole scavenger.…”

Insights on advanced substrates for controllable fabrication of photoanodes toward efficient and stable photoelectrochemical water splitting

“…In an interesting study, Lee and coworkers reported the fabrication of bendable BiVO 4 crystalline thin films on a MgO/Y 2 O 3 /Al 2 O 3deposited Hastelloy (M-has) substrate. 293 To reduce the structural mismatch between BiVO 4 and the substrate, the authors also used SrRuO 3 (SRO)/SrTiO 3 (STO) template layers. Furthermore, a WO 3 layer was added between BiVO 4 films and SRO/STO layers to form a type II heterojunction for charge separation and transfer (as shown in Figure 28D,E).…”

“…(E) Schematic of the bent BVO/WO thin-film photoanode. (F, G) PEC performance comparison of the pristine BVO/ WO and tensile-bent BVO/WO photoanodes.Reproduced with permission: Copyright 2021, American Chemical Society 293.…”

Ag-nanoparticle-decorated ZnO/ZnSe core-shell heterostructure and its enhanced photoelectrochemical performance

“…The oxide semiconductor materials such as zinc oxide (ZnO) have attracted considerable research attention owing to their unique photoelectric properties, especially in the field of photoelectrochemistry [1][2][3][4] , and has achieved many research advances in various photoelectric application, including photodetector, semiconductor biosensor and photocatalytic device, etc [5][6][7][8][9] . However, as a wide band gap semiconductor, ZnO (3.37 eV) absorbs 5% of the solar spectrum in ultraviolet (UV) range.…”