Single Step Electrochemical Semi‐Exfoliated S‐Doped Graphene‐Like Structures from Commercial Carbon Fiber as Efficient Metal‐Free Catalyst for Hydrogen Evolution Reaction

Abstract The hydrogen evolution reaction (HER) is the core of electrocatalysis and plays a crucial role in water splitting to obtain hydrogen. It has been inevitable to develop metal‐free catalysts in terms of sustainability, the environment, and economic feasibility. Carbon‐based materials are called metal‐free electrocatalysts and are regarded as one of the most promising candidates due to their abundant source, but they often show poor activity. The strategic aim of this study is to convert commercial carbon fiber into heteroatom‐doped graphene‐like surfaced fibers via an eco‐friendly and fast intercalation/semi‐exfoliation mechanism called Yucel's method. Furthermore, X‐ray photoelectron spectroscopy (XPS) verified that the intercalation has successfully taken place and that the heteroatoms (S, O) are connected to the graphene‐like structure by covalent bonds. The catalysts with 1 M H 2 SO 4 showed superior HER performance compared to bare CF.