Waste-to-Energy Approach: Snail Shell-Derived Electro/Nanocatalysts for Direct Methanol Fuel Cells

In recent years, in the presence of environmental pollution, green materials have emerged as a research hotspot. The value-engineered design of electron nanocatalysts using low-cost biomaterials has demonstrated special electrocatalytic efficiency and performance in methanol oxidation reactions within direct methanol fuel cells (DMFCs). These electro/nanocatalysts were successfully heat-treated in a study involving multiple temperature controls and activation. The research involved studying samples C-400, C-600, and C-800, which were carbonized at temperatures of 400, 600, and 800 °C from snail shells. Next, these samples were activated using potassium hydroxide, resulting in samples AC-400, AC-600, and AC-800. Moreover, the ability of the resulting electron nanocatalysts, as heat-treated catalysts, to enhance the electrocatalytic efficiency of methanol oxidation reactions, along with the significant effects of temperature variations before and after activation, was investigated. The surface area of the sample increased successfully from 4.6691 m2/g to 14.1763 m2/g after activation, while the pore volume increased from 0.02225 m3/g to 0.07233 m3/g. The results clearly show that methanol oxidation reactions were more efficient and active on the surface of the electron nanocatalyst at 800 °C (AC-800). The current density successfully increased from 22.76 mA/cm2 to 49.89 mA/cm2 after the addition of methanol to C-800, whereas it increased significantly from 25.7 mA/cm2 to 65.24 mA/cm2 in AC-800 (after activation). Furthermore, the C-400, C-600, C-800, AC-400, AC-600, and AC-800 electro/nanocatalysts exhibited novel power densities of 12.6, 18.2, 29.7, 16.6, 22.86, and 39.56 mW/cm2, respectively. This was further confirmed by their morphological, structural, and electrochemical characteristics. The synthesized materials are proven to be sustainable carbon materials for electron nanocatalyst support and methanol electro-oxidation in DMFC systems because of their low cost, eco-friendliness, high performance, and enhanced porous structure. Moreover, this research provides an effective waste-to-energy approach for converting snail shell biomass into valuable functional carbon materials for renewable energy applications.