Synthesis of AgMn₃O₄/C and AgSn/C Cathodes and Pd/C Anode Catalyst for Sorbitol Membraneless Alkaline Fuel Cells

This study explored the synthesis of catalysts for sorbitol membraneless alkaline fuel cells (SMAFC) that target both cathode and anode fuels. The synthesized catalysts included AgMn3O4/C, AgSn/C, and Pd/C for the cathode and anode. This research examined the electrochemical properties of alkaline fuel oxidation by employing sorbitol as the fuel. Various sorbitol concentration ratios, ranging from 0.1 to 0.5 M per 0.1 M alkaline KOH solution, were analyzed using cyclic voltammetry with a scan rate of 0.01 V/s. At a concentration of 0.1 M sorbitol, the Pd/C catalyst was identified as an anode catalyst. The oxidation sites exhibited the greatest potential difference within the range of –0.5 to 0.5 V, resulting in a maximum current density of 0.75 mA/cm–2. The AgMn3O4/C and AgSn/C catalysts were tested as cathode side catalysts in the reduction reaction using sorbitol solution concentrations ranging from 0.1 to 0.5 M per 0.1 M alkaline KOH solution. The reduction reaction of the catalyst decreased with increasing sorbitol concentration. It appears that hydrocarbon adsorption did not result in any oxidation reactions. As sorbitol fuel crosses from the anode to the cathode side, the cathode catalyst must be resistant to oxidation reactions. An alkaline membraneless sorbitol fuel cell was tested, achieving peak performance with specific catalyst pairings. The cell, fueled by a 0.1 M sorbitol solution and 0.1 M potassium hydroxide at the anode (2.5 mL/min flow) and air at the cathode (3 mL/min flow), generated a maximum current density of 0.40 A/m² and a maximum power density of 0.155 W/m². These results were observed using a Pd/C catalyst for the anode and an AgSn/C catalyst for the cathode. The average calculated value of the number of electrons involved in the catalytic reaction (n) was 3.20. HIGHLIGHTS The AgMn₃O₄/C and AgSn/C catalysts at 0.01 V/s dilution influenced the reduction reaction. Effective performance requires cathode oxidation resistance. Hydrodynamic voltammetry and RDE confirmed the good kinetics and favorable conditions of the AgSn/C catalyst, with an average electron transfer number of 3.20. The experiments revealed that the Pd/C anode and AgSn/C cathode yielded the highest current and power densities. GRAPHICAL ABSTRACT