<i>Sargassum</i> ‐Based Biocarbon as Support for Green‐Synthesized Ag Nanoparticles in CO ₂ Electroreduction

Abstract The escalating atmospheric CO 2 concentration has emerged as a critical environmental problem, significantly contributing to global warming and climate change. Addressing this issue, this study explores the electrochemical reduction reaction of CO 2 (CO 2 RR) utilizing green‐synthesized silver nanoparticles (AgNPs) supported onto biocarbon derived from Sargassum spp. AgNPs were synthesized via a green approach using AgNO 3 at varying concentrations and characterized using UV–vis spectroscopy, FTIR, XRD, Raman spectroscopy, and TEM. The data validated the synthesis of AgNPs with a predominantly spherical morphology and an average size of approximately 20 nm, characterized by a surface plasmon resonance (SPR) band within the 390–450 nm range in the UV–vis spectrum. FTIR analysis revealed the presence of various functional groups in the Sargassum extract, which are likely involved in the reduction and stabilization processes during nanoparticle synthesis. Subsequently, electrocatalysts were prepared by integrating AgNPs into the biocarbon matrix and evaluated for CO 2 RR activity via cyclic voltammetry (CV) in 0.1 M KHCO 3 under both CO 2 ‐saturated and CO 2 ‐free conditions. The CV analysis established an electrochemical window between −1.8 and 0.05 V vs. saturated calomel electrode (SCE), within which CO 2 reduction occurred. These findings demonstrate that the synthesized AgNP‐supported biocarbon exhibits promising characteristics for CO 2 electroreduction applications.