Ionic liquid in situ functionalized carbon nanotubes as metal-free catalyst for efficient electrocatalytic hydrogen evolution reaction

The development of cost-effective and high-performance catalysts for the production of hydrogen via electrocatalytic water splitting is crucial for meeting the increasing energy demand and expanding the hydrogen economy. In this study, a series of metal-free carbon nanotube (CNT) catalysts were designed and in situ functionalized by imidazolium ionic liquids (ILs) for enhanced electrocatalytic hydrogen evolution reaction (HER). The theoretical calculations and experimental results reveal that the functionalization of CNTs with imidazolium ILs facilitated the electron transfer process and exhibited superior hydrogen adsorption, thereby enhancing the performance of the HER. In particular, CNT-IM-Cl displays excellent electrocatalytic activity and shows a low onset overpotential and Tafel slope of 80 mV and 38 mV dec-1, respectively. This study highlights the significant potential of IL in situ functionalized metal-free CNTs for the electrocatalytic HER and provides insight into the structure design of highly efficient electrocatalysts.