Enhancing photoelectrochemical water splitting by combining work function tuning and heterojunction engineering

• Published in: Nature communications Vol. 10; no. 1; pp. 3687 - 9
• Main Authors: Ye, Kai-Hang, Li, Haibo, Huang, Duan, Xiao, Shuang, Qiu, Weitao, Li, Mingyang, Hu, Yuwen, Mai, Wenjie, Ji, Hongbing, Yang, Shihe
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 15-08-2019; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 140/133; 140/146; 639/301/299/890; 639/4077/4072/4062; 639/638/298/917; Bismuth oxides; Boron; Boron nitride; Carbon nitride; Charge transfer; Circuits; Current efficiency; Doping; Efficiency; Energy dissipation; Energy loss; Heterojunctions; Holes (electron deficiencies); Humanities and Social Sciences; Hydrogen; Interfacial energy; Laboratories; Light; Molybdenum; multidisciplinary; Optical properties; Optimization; Photoelectrochemical devices; Science; Science (multidisciplinary); Separation; Splitting; Vanadate; Vanadates; Water splitting; Work functions
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-11586-y

We herein demonstrate the unusual effectiveness of two strategies in combination to enhance photoelectrochemical water splitting. First, the work function adjustment via molybdenum (Mo) doping significantly reduces the interfacial energy loss and increases the open-circuit photovoltage of bismuth vanadate (BiVO
4
) photoelectrochemical cells. Second, the creation and optimization of the heterojunction of boron (B) doping carbon nitride (C
3
N
4
) and Mo doping BiVO
4
to enforce directional charge transfer, accomplished by work function adjustment via B doping for C
3
N
4
, substantially boost the charge separation of photo-generated electron-hole pairs at the B-C
3
N
4
and Mo-BiVO
4
interface. The synergy between the above efforts have significantly reduced the onset potential, and enhanced charge separation and optical properties of the BiVO
4
-based photoanode, culminating in achieving a record applied bias photon-to-current efficiency of 2.67% at 0.54 V vs. the reversible hydrogen electrode. This work sheds light on designing and fabricating the semiconductor structures for the next-generation photoelectrodes.
While photoelectrodes represent a promising solar-to-fuel conversion technology, material challenges limit performances. Here, authors improve the onset potential and charge separation of bismuth vanadate photoanode water splitting performances by work function tuning and heterojunction engineering.