This study explores the synthesis and characterization of platinum (Pt), nickel (Ni), and cobalt (Co)-based electrocatalysts using the sol–gel method. The focus is on the effect of different support materials on the catalytic performance in alkaline media. The sol–gel technique enables the production of highly uniform electrocatalysts, supported on carbon-based substrates, metal oxides, and conductive polymers. Various characterization techniques, including X-ray diffraction (XRD) and scanning electron microscopy (SEM), were used to analyze the structure of the synthesized materials, while their electrochemical properties, which are relevant to their application in unitized regenerative fuel cells (URFCs), were investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). This hydrogen energy-converting device integrates water electrolyzers and fuel cells into a single system, reducing weight, volume, and cost. However, their performance is constrained by the electrocatalyst’s oxygen bifunctional activity. To improve URFC efficiency, an ideal electrocatalyst should exhibit high oxygen evolution (OER) and oxygen reduction (ORR) activity with a low bifunctionality index (BI). The present study evaluated the prepared electrocatalysts in an alkaline medium, finding that Pt25-Co75/XC72R and Pt75-Co25/N82 demonstrated promising bifunctional activity. The results suggest that these electrocatalysts are well-suited for both electrolysis and fuel cell operation in anion exchange membrane-unitized regenerative fuel cells (AEM-URFCs), contributing to improved round-trip efficiency.

The aim of this study is to explore the feasibility of using flotation wastewater from copper–porphyry ore processing to synthesize a gel that serves as a precursor for a polymer nanocomposite used in supercapacitor electrode fabrication. These wastewaters—characterized by high acidity and elevated concentrations of metal cations (Cu, Ni, Zn, Fe), sulfates, and organic reagents such as xanthates, oil (20 g/t ore), flotation frother (methyl isobutyl carbinol), and pyrite depressant (CaO, 500–1000 g/t), along with residues from molybdenum flotation (sulfuric acid, sodium hydrosulfide, and kerosene)—are byproducts of copper–porphyry gold-bearing ore beneficiation. The reduction of Ni powder in the wastewater induces the degradation and formation of a gel that captures both residual metal ions and organic compounds—particularly xanthates—which play a crucial role in the subsequent steps. The resulting gel is incorporated during the oxidative polymerization of aniline, forming a nanocomposite with a polyaniline matrix and embedded xanthate-based compounds. An asymmetric supercapacitor was assembled using the synthesized material as the cathodic electrode. Electrochemical tests revealed remarkable capacitance and cycling stability, demonstrating the potential of this novel approach both for the valorization of industrial waste streams and for enhancing the performance of energy storage devices.

Advanced alkaline water electrolysis (AWE) in “zero-gap” configuration is a promising approach for low-temperature hydrogen production, but its efficiency strongly depends on the design and surface chemistry of nickel-based electrodes. Here, we present a simple dip-and-drying method (DDM) to modify commercial nickel foam with a Ni–FeOOH/PTFE microporous catalytic layer and evaluate its electrochemical performance in 1 M KOH and in a laboratory zero-gap cell with a Zirfon^® Perl 500 UTP diaphragm, through circulating 25 wt.% KOH. The FeSO₄-assisted DDM treatment generates mixed Ni–Fe oxyhydroxide surface species, while PTFE imparts control hydrophobicity, enhancing both catalytic activity and gas-release behavior. Annealing the electrode (DDM-NF-CAT-A) results in a cell voltage of 2.45 V at 1 A·cm⁻² and 80 °C, demonstrating moderate performance comparable to other Ni-based electrodes prepared via low-complexity methods, though below that of optimized state-of-the-art zero-gap systems. Short-term durability tests (80 h at 0.5 A·cm⁻²) indicate stable operation, but long-term industrial performance was not assessed. These findings illustrate the potential of the DDM approach as a simple, low-cost route to structured nickel foam electrodes and provide a foundation for further optimization of catalyst loading, microstructure, and long-term stability for practical AWE applications.

The aim of this study is to explore the feasibility of using flotation wastewater from copper-porphyry ore processing to synthesize a gel that serves as a precursor for a polymer nanocomposite used in supercapacitor electrode fabrication. These wastewaters, characterized by high acidity and elevated concentrations of metal cations (Cu, Ni, Zn, Fe), sulfates, and organic reagents such as xanthates, oil (20 g/t ore), flotation frother (methyl isobutyl carbinol), and pyrite depressant (CaO, 500–1000 g/t), along with residues from molybdenum flotation (sulfuric acid, sodium hydrosulfide, and kerosene), are byproducts of copper-porphyry gold-bearing ore beneficiation. A controlled electrolysis process using nickel foam immersed in the wastewater induces degradation and formation of a gel that captures both residual metal ions and organic compounds—particularly xanthates—which play a crucial role in the subsequent steps. The resulting gel is incorporated during the oxidative polymerization of aniline, forming a nanocomposite with a polyaniline matrix and embedded xanthate-based compounds. An asymmetric supercapacitor was assembled using the synthesized material as the cathodic electrode. Electrochemical tests revealed remarkable capacitance and cycling stability, demonstrating the potential of this novel approach both for the valorization of industrial waste streams and for enhancing the performance of energy storage devices.

This work demonstrates for the first time a cost-effective modification of stainless-steel electrodes with an Fe³⁺ precursor via the deep-and-dry method (DDM) at processing temperatures between 20 °C and 80 °C, enabling their simultaneous applicability for both OER and HER in zero-gap electrolyzers. The approach offers a durable and economical alternative to conventional nickel-based electrodes. Morphological and compositional analyses by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) demonstrated a pronounced temperature-dependent evolution of surface features. At 20 °C, the coatings exhibited high porosity and incomplete coverage, whereas treatment at 60 °C yielded a compact, uniform, and continuous layer with suppressed Fe/Ni exposure and enhanced oxygen incorporation. Electrochemical characterization in 25% KOH by cyclic voltammetry and polarization measurements confirmed reversible redox behavior and comparable electrochemically active surface areas across all samples, with the 60 °C electrodes achieving the highest catalytic activity. In electrolysis cell tests (zero gap), the optimized electrodes delivered low cell voltages, current densities up to 1.35 A cm⁻², and power outputs approaching 3.5 W cm⁻². These results establish processing temperature as a decisive factor for tailoring the morphology, composition, and performance of DDM-fabricated electrodes, underscoring the promise of 60 °C-treated electrodes for efficient hydrogen production.