期刊
ADVANCED SCIENCE
卷 7, 期 3, 页码 -出版社
WILEY
DOI: 10.1002/advs.201901382
关键词
ambipolar carrier; density function theory; electrochemical microcells; hydrogen evolution; model catalysis
资金
- Danish National Research Foundation
- AUFF-NOVA project from Aarhus Universitets Forskningsfond
- EU H2020RISE 2016-MNR4S Cell project
- Natural Science Foundations of China [51901013]
- UNL Holland Computing Center
- Fundamental Research Funds for the Central Universities, China [YJ201893]
- State Key Lab of Advanced Metals and Materials, China [2019-Z03]
An improved understanding of the origin of the electrocatalytic activity is of importance to the rational design of highly efficient electrocatalysts for the hydrogen evolution reaction. Here, an ambipolar single-crystal tungsten diselenide (WSe2) semiconductor is employed as a model system where the conductance and carrier of WSe2 can be individually tuned by external electric fields. The field-tuned electrochemical microcell is fabricated based on the single-crystal WSe2 and the catalytic activity of the WSe2 microcell is measured versus the external electric field. Results show that WSe2 with electrons serving as the dominant carrier yields much higher activity than WSe2 with holes serving as the dominant carrier even both systems exhibit similar conductance. The catalytic activity enhancement can be characterized by the Tafel slope decrease from 138 to 104 mV per decade, while the electron area concentration increases from 0.64 x 10(12) to 1.72 x 10(12) cm(-2). To further understand the underlying mechanism, the Gibbs free energy and charge distribution for adsorbed hydrogen on WSe2 versus the area charge concentration is systematically computed, which is in line with experiments. This comprehensive study not only sheds light on the mechanism underlying the electrocatalysis processes, but also offers a strategy to achieve higher electrocatalytic activity.
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