In-situ designing of multiple metals electrocatalysts with high active sites and performance is the main challenge for hydrogen evolution reaction (HER). So in this work, 3D-rGO was easily obtained from 2D-graphene by a simple one-step hydrothermal method to create the interspace sites and active surface area. The Ni–Co–Mo tri-metallic@3D-rGO was synthesized and fully characterized by different techniques, e.g., FT-IR, XRD, Raman, FE-SEM, TEM, EDS, mapping, ICP-OES, AFM, voltammetry, and electrochemical impedance spectroscopy. According to the FE-SEM and TEM images, the Ni–Co–Mo tri-metallic@3D-rGO has a crumpled-formed structure. The as-prepared nanocomposite has high HER performance with a low potential of −0.11 (vs. RHE) to deliver 10 mA cm^–2 and Tafel slope of 68 mV dec⁻¹ for Pt and −0.25 V (vs. RHE) to deliver 10 mA cm⁻² and Tafel slope of 110 mV dec⁻¹ for graphite counter electrode. Furthermore, the 3D structure illustrates high long-term durability in the HER process for 1000 continuous cycles and 12 h operation at −0.42 V (vs. RHE) for Pt and graphite counter electrode. It's noticeable HER performance has the synergetic effect between 3D-rGO and tri-metallic structure with high porosity and electrical conductivity, enhancing HER kinetic.

Keywords: Multiple metals electrocatalysts Three-dimensional reduced graphene oxide crumpled structure Electrochemical technique Tafel slope