Preparation and Evaluation of Nickel Nanoparticles Supported on the Polyvinylpyrrolidone-Graphene Composite as a Durable Electrocatalyst for HER in Alkaline Media

Abstract

Low-cast non-noble-based catalysts with high activity and durability are the choices to replace expensive Pt-based catalysts for hydrogen evolution reaction (HER). In this work, polyvinylpyrrolidone (PVP)-modified graphene (PVP-rGO) was synthesized as a composite with a high surface area and additional functional groups for Ni nanoparticle support. Loading of nickel nanoparticles on the PVP-rGO was optimized to obtain an effective non-noble catalyst (Ni/PVP-rGO) for HER in alkaline media. Inductively coupled plasma optical emission spectrometry (ICP-OES) results demonstrated a relatively good accordance between theoretical and experimental metal loading by this facile synthesis procedure. The structure and morphology of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) techniques. The activity and stability of the prepared catalysts (with and without PVP) were investigated at HER in alkaline media by different electrochemical techniques. A Tafel slope of 119 mV dec−1 was obtained for Ni/PVP-rGO, which was consistent with the Volmer reaction as the rate determining step (RDS) of HER mechanism. Also, an acceptable durability in HER performance was obtained by Ni/PVP-rGO (working over 62.5 h and 5000 cycles without a notable lost). These results make it as a promising catalyst which could be employed in the cathode side of water electrolyzer in alkaline media.