Produção de hidrogênio e oxigênio em um voltâmetro de hofmann com diferentes eletrodos e concentrações de eletrólito

Abstract

Given the urgency of climate change and the need to transition from a fossil fuel energy matrix to renewable energies with a low carbon footprint, research and development in new technologies such as hydrogen energy is necessary. This work seeks to determine, through alkaline water electrolysis in a Hofmann voltameter, using two electrodes of different materials, titanium and stainless steel, at three concentrations of potassium hydroxide (50, 150, and 250 g/L), which electrode material has greater electrolysis efficiency. The study was conducted experimentally in triplicate, using a predetermined volume of hydrogen and the same current density for both electrodes. Faradaic and thermal efficiencies were calculated in two different scenarios: under standard temperature and pressure conditions and under real laboratory conditions, using a methodology from a leading authority in the study of electrolysis. The results showed superior efficiency of the titanium electrode compared to the stainless steel electrode at all concentrations. At the highest KOH concentration tested (250 g/L) and under real temperature and pressure conditions, the titanium electrode achieved a faradaic efficiency of 39.1%, compared to 27.8% for the stainless steel electrode. At the same concentration, the titanium electrode obtained a thermal efficiency of 47.6%, compared to 33.9% for the stainless steel electrode. This superiority is justified because the titanium electrode comes from the electrolytic industry and has a coating that improves its performance, while the stainless steel electrode used is made with commercial screws.