碳纳米管表面Co/MoSe2莫特-肖特基异质结的构筑及高效析氢性能

Mott-Schottky heterojunction formation between Co and MoSe2 on carbon nanotubes for superior hydrogen evolution

  • 摘要: 二硒化钼(MoSe2)是一种先进的电解水制氢催化剂,但其电催化性能还远不如金属铂(Pt)。将半导体与金属结合构建莫特-肖特基异质结是一种提高催化活性的有效途径。本文采用溶胶-凝胶工艺和热还原法在碳纳米管表面制备了金属钴(Co)/半导体MoSe2莫特-肖特基异质结(Co/MoSe2@CNT)。实验和理论计算结果表明Co/MoSe2莫特-肖特基异质结导致电子在界面处重新分布并形成一个内建电场,这不仅可以优化氢原子吸附的自由能,还可以提高析氢过程中电荷的传输效率。因此,Co/MoSe2@CNT获得了优异的析氢活性:在电流密度为10 mA cm−2时的过电势仅为185 mV、Tafel斜率为 69 mV dec−1。这项工作提供了一种新的策略来制备Co/MoSe2莫特-肖特基异质结,并突出了莫特-肖特基效应的重要意义,有利于未来开发出更高效的莫特-肖特基电催化剂。

     

    Abstract: Molybdenum selenide (MoSe2) has been regarded as an advanced electrocatalyst for the hydrogen evolution reaction (HER). However, its electrocatalytic performance is far inferior to platinum (Pt). Combining semiconductors with metals to construct Mott-Schottky heterojunctions has been considered as an effective method to enhance HER activity. In this work, we report a typical Mott-Schottky heterojunction composed of metal Co and semiconductor MoSe2 on carbon nanotubes (Co/MoSe2@CNT), prepared by a sol-gel process followed by thermal reduction. The characterization and theoretical calculations show that a Co/MoSe2 Mott-Schottky heterojunction can cause electron redistribution at the interface and form a built-in electric field, which not only optimizes the free energy of hydrogen atom adsorption, but also improves the charge transfer efficiency during hydrogen evolution. Thus, the Co/MoSe2@CNT has excellent catalytic activity with a low overpotential of 185 mV at 10 mA cm−2 and a small Tafel slope of 69 mV dec−1. This work provides a new strategy for constructing Co/MoSe2 Mott-Schottky heterojunctions and highlights the Mott-Schottky effect, which may inspire the future development of more attractive Mott-Schottky electrocatalysts for H2 production.

     

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