On-Surface Synthesis of Pentalene Rich Nanoribbons for Exploring Their Activity in Hydrogen Evolution Reaction

Understanding the structure-performance relationship is crucial for revealing the active site of carbon-based metal-free electrocatalysts (C-MFECs). To experimentally reveal the role of 5-membered carbon rings in the hydrogen evolution reaction (HER), in this work, two types of well-defined nanoribbons with a pentalene moiety were synthesized on Au(111) as model catalysts via on-surface reactions under ultrahigh vacuum. Both types of nanoribbon-modified Au(111) electrodes exhibited better HER performance than bare Au(111), with approximately 50 mV lower overpotential at a current density of -0.4 mA cm^-2. Further measurement of the temperature-effect on HER provided a more comprehensive analysis of the mechanistic role of pentalene. Our findings provide direct experimental evidence and key kinetic parameters, enabling rational control over catalysis through pentalene engineering and presenting a novel strategy for the design and optimization of high-performance C-MFECs.