Estudo da geração de hidrogênio com resíduo de erva-mate (Ilex Paraguariensis St. Hill)

Abstract

Hydrogen is a clean energy carrier with high energy density, capable of replacing fossil fuels and contributing to the reduction of greenhouse gas emissions, particularly when produced sustainably, such as through water electrolysis powered by renewable energy. However, electrolysis remains limited by high energy consumption and elevated operational costs, motivating the development of strategies to enhance efficiency and reduce expenses, such as the use of more conductive electrodes, more efficient cell designs, and new electrolytes. Among these strategies, the use of alternative electrolytes stands out, capable of increasing the conductivity of water and reducing the hydrogen evolution overpotential, as well as additives derived from agroindustrial residues rich in cellulose. This study investigated the application of industrial residues of yerba mate, abundant in the yerba mate industry, in electrolysis with 3 mol/L formic acid. Solutions containing 0.01%, 0.5%, and 1% of residue mass per solution mass were tested in an electrolytic cell with a working electrode of stainless steel 254, a platinum counter electrode, and an Ag/AgCl reference electrode, for Open Circuit Potential, Cathodic Potentiodynamic Polarization, and Chronoamperometry assays. The results indicated that the 0.5% concentration reduced the overpotential by up to 71 mV and achieved the most favorable cost–benefit ratio, with a cost of 4.233×10⁻⁷ reais per unit area and a 15% yield increase compared to the control sample. These findings demonstrate that the addition of small amounts of yerba mate residue in combination with formic acid generates a synergistic effect, improving the efficiency and economic feasibility of green hydrogen production while simultaneously valorizing an agro-industrial residue.