Unveiling the Role\nof Pyridinic Nitrogen and Diacetylene\nin the Hydrogen Evolution Reaction through Model Catalysts Prepared\nby On-Surface Reactions

Metal-free carbon materials (MFCMs) have extensive applications\nin electrocatalysis because of their comparable catalytic activity\nto that of Pt/C in some cases. Understanding the structure–property\nrelationship is crucial for the reasonable design of more efficient\ncatalysts. To reveal the structure–property relationship of\nthe hydrogen evolution reaction (HER), we prepared nanowire model\ncatalysts on single-crystalline Au(111) electrodes through state-of-the-art\non-surface synthesis. Temperature-dependent experiments were conducted\nto evaluate the HER activity of the nanoribbons functionalized with\npyridinic nitrogen and diacetylene. According to our electrochemical\nresults (overpotential, current density <i>j</i><sub>0</sub>, and apparent activation energy), we demonstrate that the participation\nof diacetylene can promote the catalytic reaction for the HER through\na synergistic effect. Based on the analysis of the activation entropy\nfor the model catalysts, we attribute the synergistic effect of diacetylene\ngroups to the large area of π···H–O bonding\nin the electric double layer, thus providing direct insight into the\nstructural–property relationship of polymerized nanoribbons\nfor the HER through the rational design of precursor structures. The\nnanoribbons prepared by on-surface synthesis can serve as prototype\nsystems for model catalytic research on MFCMs.