Electrochemical behavior of ammonium formate as a potential fuel

• Ammonium formate systematically studied as a novel hydrogen-rich fuel. • Demonstrated performance in membrane-free electrochemical cells. • Effect of fuel concentration and operating temperature investigated. • Stable short-term operation without noble-metal catalysts. • Potential for low-cost and scalable clean energy applications. This study investigates ammonium formate (NH 4 HCO 2 ) as a promising hydrogen-rich fuel for membrane-free electrochemical energy conversion. Owing to its low cost, high solubility, and its role as a chemical hydrogen source, ammonium formate presents a significant potential as a scalable alternative to conventional fuels. In this work, its electrochemical behavior is evaluated in an H-type cell under varying temperature and concentration conditions, with two electrode configurations, stainless steel-stainless steel (SS-SS) and aluminum–stainless steel (Al-SS). The performance is assessed through voltage–time profiles, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The Al-SS system achieves the highest power density of ∼200 mW.cm −2 and a current density of ∼275 mA.cm −2 at 80 °C with 30 g of fuel, whereas the SS-SS setup demonstrates improved voltage stability corresponding to a power density of ∼170 mW.cm −2 . Moreover, increasing the reaction temperature from 30 °C to 80 °C increases the electrical conductivity from 0.28 S.cm −1 to 0.85 S.cm −1 . Similarly, increasing the ammonium formate concentration from 5 g to 30 g increases the electrical conductivity from 0.05 S.cm −1 to 0.28 S.cm −1 . These results confirm the viability of ammonium formate as a thermally tunable and cost-effective fuel for sustainable, membrane-free fuel cell applications.