Against the background of escalating global electronic waste (e-waste) and its rich reservoir of elements, this research addresses the exploitation of precious metals from discarded CPUs for potential applications in hydrogen production. The study systematically explores the influence of varied CPU sample preparation techniques on the formation of an electrode’s catalytic layer and the kinetics of the hydrogen evolution reaction (HER) in alkaline media. Four distinct e-waste samples, each subjected to different preparation protocols, were employed as sources in electrodeposition baths. The electrocatalytic efficiency of the resulting electrodeposited cathodes was evaluated, with the AR-CPU-1.4M electrode demonstrating superior properties. Morphological insights from SEM, coupled with elemental data from EDS and ICP analyses, revealed the intricate relationship between sample preparation, electrode characteristics, and HER kinetics. Notably, gold deposits and a prominent copper concentration emerged as defining attributes of our findings. This research underscores the potential of e-waste-derived metals, particularly in hydrogen production, providing an avenue for sustainable metal recovery and utilization.

Carbon-based electrocatalysts decorated with Pt and Ni nanoparticles were introduced herein to increase the efficiency of the water splitting process and thus reduce the price of the produced green hydrogen. The materials were prepared by innovative direct carbonization of ionic liquids containing the corresponding metal, thereby eliminating the need for additional solutions and templates. The structural integrity of the materials was validated through X-ray diffraction analysis and Fourier-transform infrared spectroscopy. The electrochemical performance of these materials in catalyzing hydrogen (HER) and oxygen (OER) evolution reactions was evaluated using voltammetry and electrochemical impedance spectroscopy, uncovering distinct behaviors and highlighting the role of ionic liquid in tailoring materials’ properties and performance. Specifically, the presence of Ni was observed to enhance the catalytic performance towards the HERs due to the interaction of Ni nanoparticles and a higher amount of sp²-hybridized carbon present. In contrast, incorporating Pt into the carbon matrix was found to augment the catalytic activity for OERs with a Tafel slope of 129 mV dec⁻¹ and a current density of 10 mA cm⁻² reached at a potential of 1.67 V. Moreover, chronoamperometric measurements evidenced materials’ steady performance under both HER and OER conditions. These findings of good activity and stability showed that the introduced approach of synthesis of carbon electrocatalysts decorated with heteroatoms by direct carbonization of ionic liquids holds great promise for the synthesis of efficient and affordable electrocatalysts for green hydrogen production.

This study explores the production of activated carbon (AC) from lemon peel, an agricultural waste, using phosphoric acid activation, presenting a sustainable alternative to conventional AC derived from fossil fuels. The processed lemon peel AC exhibited promising electrochemical properties suitable for supercapacitors, including high specific capacitance of 138.9 F/g at a scan rate of 20 mV/s and excellent stability in an alkaline environment. These findings demonstrate the potential of bio-waste as a cost-effective and environmentally friendly precursor for AC production. This approach not only supports waste minimization but also contributes to sustainable resource utilization in the field of energy storage.