A low-cost platinum-free electrocatalyst based on carbon quantum dots decorated Ni–Cu hierarchical nanocomposites for hydrogen evolution reaction

The effective Ni–Cu bimetallic nanocomposite was deposited on a glassy carbon electrode, GCE, that modified with carbon quantum dots, CQDs. The deposition process was done by one-step and controllable electrochemical method in an electrolyte of nickel and copper sulfate. The structural properties of composite studied by techniques such as X-ray diffraction, XRD, energy dispersive X-ray analysis, EDX, field emission scanning electron microscopy, FESEM, and transmission electron microscopy, TEM. Ni–Cu/RCQDs nanocomposite was applied as a cathode for catalysis of hydrogen evolution reaction, HER, in acidic media by cyclic voltammetry, CV, linear sweep voltammetry, LSV, chronoamperometry, CA, and electrochemical impedance spectroscopy, EIS. The onset potential, Eonset, for the evolution of hydrogen at the current density of −10 mA cm−2 for Ni–Cu/RCQDs was −230 mV vs. SHE that had a 100 mV shift to positive voltages in comparison with Ni–Cu catalyst. It can be related to the synergistic effect between metallic nanoparticles. V. dec−1, respectively.