期刊
ACS APPLIED ENERGY MATERIALS
卷 2, 期 8, 页码 5438-5445出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsaem.9b00420
关键词
hematite photoanode; photoelectrochemical water splitting; electrochemical doping; proton incorporation; protonation and annealing; suppressed charge recombination
资金
- Paul Scherrer Institute
- NCCR MARVEL - Swiss National Science Foundation
Hematite as promising photoanode for solar water splitting suffers from severe bulk and surface charge recombination. This work describes that a protonation-annealing treatment can effectively suppress both bulk and surface charge recombination in hematite. Protons/electrons are electrochemically incorporated into hematite under 0.2 VRHE followed by annealing at 120 degrees C. The photocurrent density increases from similar to 0.9 to 1.8 mA cm(-2) at 1.23 VRHE under 1 sun, and further to 2.7 mA cm(-2) after loading cobalt phosphate, stabilizing at round 2.4 mA cm(-2). A cathodic shift of the onset potential of photocurrent is also observed. H2O2 oxidation, impedance spectroscopy, and Mott-Schottky measurements show that the protonation suppresses bulk recombination and enhances donor density, but introducing more surface recombination. The annealing reduces surface recombination, while preserving relatively high bulk charge separation efficiency. Different from previous reports on the electrochemically reduced hematite, this work demonstrates that the performance improvement should be ascribed to the proton incorporation instead of the formation of Fe3O4 or metal Fe. This facile treatment by protonation and annealing could be applied in other semiconductors to promote the development of high performing photoelectrodes.
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