Design of atomically precise Au2Pd6 nanoclusters for boosting electrocatalytic hydrogen evolution on MoS2

Abstract

Atomically precise nanoclusters (NCs) have been widely used as catalysts in many reactions to investigate the structure–activity relationship due to their ultrasmall sizes, well-defined structures and precise compositions, especially bimetallic NCs can further promote the catalytic activity by the synergistic effects of heteroatoms. For electrocatalytic hydrogen evolution reaction (HER) catalysts, a common method to improve the performance is coupling with a nano-metal, but the origin of the enhancement is still unclear due to the diversity and complexity of the nanometal supported composites. Here, we take MoS₂ (a star HER electrocatalyst) as an example, to report a strategy to boost the activity and give insight into the activity enhancement of it by combining with bimetallic atomically precise NCs. The crystal structure of this new NC is determined by X-ray crystallography, and its precise composition is identified as Au₂Pd₆S₄(PPh₃)₄(C₆H₄F₂S)₆ (Au₂Pd₆ for short). The Au₂Pd₆/MoS₂ show significantly improved HER activity and robust durability compared to the single component Pd₃ or Au₂/MoS₂ and bare MoS₂. This is attributed to the appropriate adsorption behavior of H atoms on Au₂Pd₆/MoS₂ and the electronic interactions between NCs and MoS₂, according to the combination of experiment and theory. This study presents a new strategy to improve the electrocatalytic activity of 2D materials such as MoS₂ and sheds light on the origin of the promotion effects at the atomic level.