Mixture Design of NiCoMo Ternary Alloy Nanoparticles Assembled on Graphene Nanosheets and Decorated with Ru Nanoparticles: A Pt/C-like Activity for Hydrogen Evolution Reaction

The development of nanocomposites with high activity and stability to generate hydrogen as a green fuel is an interesting challenge for several industrial requirements. Here, ternary alloy nanoparticles of NiCoMo are fabricated electrochemically on graphene nanosheets (GNs) as new nanocomposites using a glassy carbon electrode (GC) base, and then the prepared electrode systems are decorated with ruthenium nanoparticles (Ru NPs). The electrodes are characterized by several surface analysis techniques. The electrocatalytic activity of the electrodes is monitored toward the hydrogen evolution reaction (HER) in alkaline solutions, and the fabrication conditions are optimized systematically based on advanced optimization methods such as central composite design (CCD) and simplex -lattice mixture design (SLMD). Initially, the electrodeposition bath parameters are investigated and optimized by CCD. Then, the SLMD analysis is utilized to obtain the optimal mole ratio of metal ions using HER kinetic data. The results revealed an optimized mole ratio of 33:27:40 for metal ions of Ni/Co/Mo in the electrodeposition bath leading to a GC-GNs-Ni0.20Co0.36Mo0.44 electrode structure. A Tafel slope of-45 mV dec(-1), j(0) of 1.26 mA cm(-2), and eta(50) of -82 mV are obtained at the optimized structure, which are close to -42 mV dec(-1) 5.93 mA cm(-2), and -48 mV obtained under the same conditions on the GC electrode modified with commercial Pt/C (GC-Pt/C). The electrode is further decorated with Ru NPs through electrodeposition to form GC-GNs-Ni-0.15,Co0.31Mo0.38/Ru-0.16. The results obtained on this electrode showed high physical and electrochemical stabilities and excellent kinetic performance for the HER, Tafel slope of -38 mV dec(-1), j, of 6.31 mA cm(-2), and eta(50) of -49 mV, which are similar or even better than the results obtained on the GC-Pt/C electrode.