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Open Access Research Article Issue
Nitrogen incorporated oxygen vacancy enriched MnCo2Ox/BiVO4 photoanodes for efficient and stable photoelectrochemical water splitting
Nano Research 2024, 17 (3): 1140-1150
Published: 26 July 2023
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Oxygen vacancies in oxygen evolution cocatalysts (OECs) can significantly improve the photoelectrochemical (PEC) water splitting performance of photoanodes. However, OECs with abundant oxygen vacancies have a poor stability when exposing to the highly-oxidizing photogenerated holes. Herein, we partly fill oxygen vacancies in a MnCo2Ox OEC with N atoms by a combined electrodeposition and sol-gel method, which dramatically improves both photocurrent density and stability of a BiVO4 photoanode. The optimized N filled oxygen vacancy-rich MnCo2Ox/BiVO4 photoanode (3 at.% of N) exhibits an outstanding photocurrent density of 6.5 mA·cm−2 at 1.23 VRHE under AM 1.5 G illumination (100 mW·cm−2), and an excellent stability of over 150 h. Systematic characterizations and theoretical calculations demonstrate that N atoms stabilize the defect structure and modulate the surface electron distribution, which significantly enhances the stability and further increases the photocurrent density. Meanwhile, other heteroatoms such as carbon, phosphorus, and sulfur are confirmed to have similar effects on improving PEC water splitting performance of photoanodes.

Research Article Issue
Nanoporous MoO3−x/BiVO4 photoanodes promoting charge separation for efficient photoelectrochemical water splitting
Nano Research 2022, 15 (8): 7026-7033
Published: 11 May 2022
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Owing to the relatively short hole diffusion length, severe charge recombination in the bulk of bismuth vanadate (BiVO4) is the key issue for photoelectrochemical water splitting. Herein, we design a nanoporous MoO3−x/BiVO4 heterojunction photoanode to promote charge separation. The efficient electron transport properties of oxygen deficient MoO3−x and the nanoporous structure are beneficial for charge separation, leading to a significantly enhanced PEC performance. The optimized MoO3−x/BiVO4 heterojunction photoanode exhibits a photocurrent density of 5.07 mA·cm−2 for Na2SO3 oxidation. By depositing FeOOH/NiOOH dual oxygen evolution cocatalysts to promote surface kinetics, a high photocurrent density of 4.81 mA·cm−2 can be achieved for PEC water splitting, exhibiting an excellent applied bias photon-to-current efficiency of 1.57%. Moreover, stable overall water splitting is achieved under consecutive light illumination for 10 h. We provide a proof of concept for the design of efficient BiVO4-based heterojunction photoanodes for stable PEC water splitting.

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