2D MXenes: A New Family of Promising Catalysts for the Hydrogen Evolution Reaction

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• 作者：Guoping Gao ; Anthony P. O’MullaneAijun Du
• 刊名：ACS Catalysis
• 出版年：2017
• 出版时间：January 6, 2017
• 年：2017
• 卷：7
• 期：1
• 页码：494-500
• 全文大小：557K
• ISSN：2155-5435

文摘

Developing highly conductive, stable, and active nonprecious hydrogen evolution reaction (HER) catalysts is a key step for the proposed hydrogen economy. However, few catalysts, except for noble metals, meet all the requirements. By using state-of-the-art density functional calculations, herein we demonstrate that 2D MXenes, like Ti₂C, V₂C, and Ti₃C₂, are terminated by a mixture of oxygen atoms and hydroxyl, while Nb₂C and Nb₄C₃O₂ are fully terminated by oxygen atoms under standard conditions [pH 0, p(H₂) = 1 bar, U = 0 V vs standard hydrogen electrode], findings in good agreement with experimental observation. Furthermore, all these MXenes are conductive under standard conditions, thus allowing high charge transfer kinetics during the HER. Remarkably, the Gibbs free energy for the adsorption of atomic hydrogen (ΔG_H*⁰) on the terminated O atoms (e.g., Ti₂CO₂) is close to the ideal value (0 eV). Our results demonstrate terminated oxygens as catalytic active sites for the HER at these materials and highlight a family of promising two-dimensional catalysts for water splitting.