标题：Reversing Interfacial Catalysis of Ambipolar WSe2 Single Crystal
作者：Wang Z.; Wu H.-H.; Li Q.; Besenbacher F.; Li Y.; Zeng X.C.; Dong M.
作者机构：[Wang, Z] College of Materials Science and Engineering, Sichuan University, Chengdu, 610065, China, Interdisciplinary Nanoscience Center (iNANO), Aarh 更多
通讯作者地址：[Zeng, X.C] Department of Chemistry, University of Nebraska-LincolnUnited States;
关键词：ambipolar carrier; density function theory; electrochemical microcells; hydrogen evolution; model catalysis
摘要：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 × 1012 to 1.72 × 1012 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. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim