Exploring the efficiency of borohydride electro-oxidation performance for borohydride fuel cell application using carbon-supported silver-nickel (Ag-Ni/C) nanospheres: emphasizing catalyst loading (wt%) on the carbon support and sample loading on electrode surface

We investigate Ag/C and Ag-Ni/C nano-powders as anode catalysts for borohydride electro-oxidation. X-ray diffraction (XRD), field emission electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) are employed to explore the structure, morphology, oxidation states and composition of the prepared electrocatalysts. The electrocatalytic performances are investigated by cyclic voltammetry (CA), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) measurements. The obtained electrochemical results confirm the better catalytic performance of Ag-Ni/C in terms of current density, stability and charge transfer resistance than Ag/C toward BH4− electro-oxidation. Among different synthesized Ag-Ni/C electrocatalysts (S-1, S-2, S-3 and S-4) with various metal loadings, the S-2 (10 wt% Ag-Ni in carbon support) catalyst displays the highest electrocatalytic activity. The CA measurement is performed for S-2 catalyst in various temperatures to find the apparent activation energy (Eapp) and the number of exchanged electrons (n) in 0.5 M NaOH + 0.01 M NaBH4 solution. We obtained n and Eapp as 2.5 at 30⁰ C and 30.6 kJ mol− 1 respectively using S-2 as anode electrocatalyst. Investigation was conducted into the catalyst loading on the surface of the glassy carbon working electrode, revealing optimal borohydride oxidation performance at a loading of 1.28 mg cm− 2. In cell performance testing, the S-2 electrocatalyst exhibited the highest open circuit voltage of 1.75 V. The Ag-Ni/C electrocatalyst, with a metal-to-carbon weight ratio of 20:80, shows potential as a promising candidate for future research as an anode material in borohydride fuel cells. [ABSTRACT FROM AUTHOR]