Electrocatalytic Applications in Hydrogen Evolution of Two Nitrogen Heterocyclic Cu(I) Coordination Polymer Modified Electrodes

Abstract

The development of low‐cost, high‐efficiency, stable, and structurally adjustable electrocatalysts for hydrogen evolution reaction (HER) is of great significance for energy conversion. In this study, two new Cu(I) coordination polymers (CPs), formulated as {[Cu(L1)](PF6)·CH2Cl2}n (1) and {[Cu2(L2)1.5(PPh3)](PF6)2}n (2) (L1 = 1,3‐bis[1‐(pyridin‐3‐ylmethyl) ‐1H‐benzimidazol‐2‐yl]propane, L2 = 1,4‐bis[1‐(3‐pyridylmethyl)‐1H‐benzimidazol‐2‐yl]butane), were synthesized by interfacial diffusion method and characterized by single‐crystal x‐ray diffraction and IR and UV–Vis spectra. Structural analysis shows that the CP‐1 is a one‐dimensional chain structure, whereas the CP‐2 is a two‐dimensional layered structure, which is due to the different coordination modes of ligands L1 (bridging chelation) and L2 (bridging). The electrocatalytic activity for HER of Cu(I) CPs was studied by preparing modified glassy carbon electrodes (CP‐1/GCE and CP‐2/GCE). Electrochemical HER studies manifest that in 0.5 M H2SO4, the overpotential (η10298K) and Tafel slope (b 298K) are −769 mV and 173 mV dec−1 for CP‐1/GCE, −933 mV and 301 mV dec−1 for CP‐2/GCE, and −930 mV and 298 mV dec−1 for bare/GCE, respectively. The η10298K and b298K of CP‐1/GCE were significantly positive shifted and decreased compared with the bare/GCE, indicating that CP‐1/GCE has significant electrocatalytic activity and electrocatalytic HER activity order is CP‐1/GCE > CP‐2/GCE ≈ bare/GCE. This work provides an important reference for the application of non‐noble metal CPs in the field of electrocatalysis.