Template Engineering of CuBi2O4 Single‐Crystal Thin Film Photocathodes

To develop strategies for efficient photo‐electrochemical water‐splitting, it is important to understand the fundamental properties of oxide photoelectrodes by synthesizing and investigating their single‐crystal thin films. However, it is challenging to synthesize high‐quality single‐crystal thin fi...

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Bibliographic Details
Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2020-10, Vol.16 (39), p.n/a
Main Authors: Lee, Jongmin, Yoon, Hongji, Choi, Kyoung Soon, Kim, Seungkyu, Seo, Sehun, Song, Jaesun, Choi, Byeong‐Uk, Ryu, Jiseung, Ryu, Sangwoo, Oh, Jihun, Jeon, Cheolho, Lee, Sanghan
Format: Article
Language:English
Subjects:
Buffer layers
Buffer solutions
Copper
Crystal defects
Crystal growth
CuBi 2O 4
Dark current
Hydrogen peroxide
Lattice vacancies
Nanotechnology
Nickel oxides
Photocathodes
Photoelectric effect
Photoelectric emission
Potassium phosphates
Pulsed laser deposition
Pulsed lasers
single‐crystal thin films
Strontium titanates
Substrates
Synthesis
template engineering
Thin films
Water splitting
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Summary:To develop strategies for efficient photo‐electrochemical water‐splitting, it is important to understand the fundamental properties of oxide photoelectrodes by synthesizing and investigating their single‐crystal thin films. However, it is challenging to synthesize high‐quality single‐crystal thin films from copper‐based oxide photoelectrodes due to the occurrence of significant defects such as copper or oxygen vacancies and grains. Here, the CuBi2O4 (CBO) single‐crystal thin film photocathode is achieved using a NiO template layer grown on single‐crystal SrTiO3 (STO) (001) substrate via pulsed laser deposition. The NiO template layer plays a role as a buffer layer of large lattice mismatch between CBO and STO (001) substrate through domain‐matching epitaxy, and forms a type‐II band alignment with CBO, which prohibits the transfer of photogenerated electrons toward bottom electrode. The photocurrent densities of the CBO single‐crystal thin film photocathode demonstrate −0.4 and −0.7 mA cm−2 at even 0 VRHE with no severe dark current under illumination in a 0.1 m potassium phosphate buffer solution without and with H2O2 as an electron scavenger, respectively. The successful synthesis of high‐quality CBO single‐crystal thin film would be a cornerstone for the in‐depth understanding of the fundamental properties of CBO toward efficient photo‐electrochemical water‐splitting. It is important to understand the fundamental photo‐electrochemical properties of CuBi2O4 single‐crystal thin film photocathodes toward efficient photo‐electrochemical water‐splitting. The synthesis of high‐quality CuBi2O4 thin films is successfully achieved through domain matching epitaxy relationship between CuBi2O4 and NiO. The stable photocurrent densities of CuBi2O4 single‐crystal thin film photocathode occur at a potential of even 0 VRHE without severe dark‐current.
ISSN:1613-6810
1613-6829
DOI:10.1002/smll.202002429