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, E onset , 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. Image 1 • CQDs were synthesized by facile and one-step electrochemical method. • One-step electrochemical method was employed for deposition of CQDs. • A green, low-cost and electrochemically-synthesized electrocatalyst was introduced. • Enhancement of hydrogen evolution reaction was evaluated. • The Ni-Cu/RCQD nanocomposite, offers promising option as cathodic electrode for HER. [ABSTRACT FROM AUTHOR]