Sustainable synthesis of MWCNTs-Supported Pd and Pt nanocatalysts using Corn-Cob derived lignin for methanol oxidation

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Low-temperature direct alcohol fuel cells (DAFCs) represent a pivotal shift toward clean and sustainable mobile power for portable electronics, yet the widespread adoption of current commercial Platinum-based electrodes remains hindered by prohibitive costs and the persistent challenge of carbon monoxide (CO) poisoning, particularly during the Methanol Oxidation Reaction (MOR). While alkaline media can improve kinetics, performance is often limited by slow OH – adsorption and intermediate accumulation. This study evaluates an innovative, green synthesis of Pt, Pd, and Pt x Pd (10-x) nanomaterials supported on multi-walled carbon nanotubes (MWCNTs), using amphiphilic lignin extracted from corn cob waste as a stabilizer, and compares it with a conventional stabilizer, such as polyvinylpyrrolidone (PVP). The results confirm the formation of a face-centered cubic (fcc) solid solution. Lignin-stabilized catalysts achieved small average particle sizes (2.40 ± 0.6 nm and 3.40 ± 0.6 nm), with the Pt 3 Pd 7 -lignin/MWCNTs system exhibiting smaller particles and a higher electrochemical surface area (ECSA) of 151.91 m 2 g −1 compared to its counterparts. Additionally, it displayed a higher mass activity (881.20 m A m g P t P d - 1 ) than the Pt 7 Pd 3 -lignin/MWCNTs system (860.18 m A m g P t P d - 1 ). Electrochemical tests demonstrate that the Pt 3 Pd 7 -lignin system offers superior catalytic activity and poisoning tolerance, attributed to the hydroxyl groups in lignin facilitating methanol access to active sites. Ultimately, these results confirm that repurposing lignin as a stabilizer is not only a sustainable green chemistry solution but a high-performance pathway for developing next-generation electrode materials for methanol electro-oxidation.