This paper investigates the toxicological concerns associated with nickel–silicon carbide (Ni–SiC) electroplated nanocomposite coatings as an alternative to conventional chromium electrodeposition.

The increasing environmental impact of electronic waste has intensified the pursuit of sustainable materials for manufacturing green electronics. This study presents the development of lignin-based hybrids with multi-walled carbon nanotubes (MWCNTs) via an environmentally friendly ultrasonication process in aqueous medium. Two hybrid materials containing 10 and 20 wt% MWCNTs were synthesized and thoroughly characterized. DLS analysis revealed better dispersion and colloidal stability due to strong physicochemical interactions between lignin and MWCNTs, while SEM and TEM images confirmed a continuous lignin matrix embedding an interconnected MWCNT network. Raman spectroscopy indicated structural ordering within the hybrids. The electrical conductivity of the hybrids reached 2–5 S/cm as evaluated by four-point probe measurements, despite the high lignin content (80–90 wt%). Electrochemical analysis suggested significantly enhanced redox activity and electron transfer kinetics, with measured electroactive surface areas increasing up to 21-fold larger compared with the unmodified electrode. The synergy between lignin and MWCNTs enabled the formation of a conductive network, highlighting these hybrids as promising, cost-effective, and sustainable materials for conductive and electrochemical applications in next-generation green electronics.

Hard chromium (HC) coatings are widely used in the metal finishing industry due to their excellent wear and corrosion resistance. However, their production involves hexavalent chromium ions, a substance classified by the European Commission as toxic, carcinogenic, and mutagenic. Moreover, boric acid, which is widely used in nickel (Ni) electroplating, has been recently restricted under REACH regulations. In response, this chapter explores the development of boric acid-free Ni-based nanocomposite coatings as safer, sustainable alternatives to HC. Environment-friendly electrolytes were developed by replacing boric acid in traditional Watts-type Ni baths with safer organic acids. Candidate acids were screened, and optimized formulations were developed incorporating ceramic (e.g., SiC) and two-dimensional (2D) nanomaterials (e.g., graphene, WS₂) as reinforcing agents. Dispersion stability was ensured via the application of ultrasonication (U/S) and validated by dynamic light scattering (DLS). The Ni composite coatings were electrodeposited using both direct current (DC) and pulse current (PC) regimes under varied conditions. The structural, morphological, and mechanical properties of the coatings were evaluated using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), Vickers microhardness testing, and water contact angle measurements. Corrosion resistance was assessed via Tafel polarization and electrochemical impedance spectroscopy (EIS). Results revealed that Ni/SiC and Ni/WS₂ composite coatings exhibit excellent mechanical and corrosion-resistant properties, surpassing 1,100 HV in microhardness and achieving a CR below 14.5 μm/year under certain plating conditions. A real-life example of Ni/SiC coatings in forged piston rods used in the automotive industry demonstrated strong potential for a viable and eco-friendly replacement of HC coatings.