Nickel and/or platinum modified crystalline silicon–carbon composites and their electrochemical behaviour towards the hydrogen evolution reaction

Abstract

Generation of hydrogen is very important, as it is one of the most desired alternatives to fossil fuels. Moreover, designing of cheap and stable electrocatalysts is the task for the efficient generation of hydrogen with reasonable activity. Materials hybridization can be considered a tool for engineering different material properties. Composites of modified silicon such as C–Si, Ni/(C–Si), Pt/(C–Si), and Pt–Ni/(C–Si) were prepared (in weight percent) and studied as electrocatalysts for the hydrogen evolution reaction (HER) in 0.5 M H2SO4 solution. The surface morphologies and chemical compositions of the composites were confirmed using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), X-ray fluorescence analysis (XRF), elemental mapping, and BET surface analysis. The electrochemical measurements of linear sweep voltammetry (LSV), Tafel plots, chronoamperometry, and electrochemical impedance spectroscopy (EIS) were used to study the behaviour of the prepared electrodes toward the hydrogen evolution process. Among the various prepared composites, [7%Pt–3%Ni]/[C–Si (1:1)] composite shows the best catalytic activity with the highest HER rate (940.95 µA cm−2 s−1), the lowest overpotential [0.358 V vs. (Ag/AgCl) ≈ 0.161 V vs. (RHE)] at 10 mA cm−2, and the lowest charge transfer resistance (2.657 Ω) compared to other prepared electrodes. In addition, it gives the highest values of 4.219 × 10−3 s−1 turn over frequency (TOF) and 642 mA g−1 mass activity. It shows good stability towards the hydrogen evolution reaction as the current density reaches about 34.28 mA cm−2 after 5 h.Graphical abstract