Valorized S/N-doped banana peel biochar as a sustainable OER electrocatalyst for green energy applications
Silvia Escudero-Curiel, Aida M. Díez, Marta Pazos, M.Á. Sanromán
Abstract
Decarbonization necessitates innovative energy solutions, such as H 2 production through water splitting reactions, which critically relies on efficient catalysts to enhance both efficiency and cost-effectiveness. Employing carbocatalysts synthesized from agro-industrial residues and co-doped with nitrogen and sulfur represents a groundbreaking strategy that not only supports decarbonization efforts but also accelerates the transition towards a circular economy model. In this study, we have developed a novel oxygen evolution reaction (OER) eco-electrocatalyst by doping banana peel-derived biochar with varying levels of thiourea. The optimal eco-electrocatalyst, 5 %-S/N@BC, significantly surpasses the efficiency of IrO 2 and outperforms many reported carbon-based electrodes in terms of initial performance and long-term stability. Notably, it achieves overpotentials of 290, 322, and 334 mV at current densities of 10, 50, and 100 mA cm −2 , respectively, over 30-h periods. The process has been optimized regarding pH, catalyst dose, and dopant concentration. Furthermore, the eco-electrocatalyst demonstrates a competitive overall water splitting behavior, attaining a notably low cell voltage of 1.58 V required for reaching 10 mA cm −2 . Comprehensive characterization using FTIR, Raman, XRD, XPS, and SEM-EDS have been conducted to validate these findings. This represents the first demonstration of a metal-free S/N@BC catalyst derived from banana peel for efficient OER. Our research highlights the significance of avoiding precious and transition metals, as well as the value of creating carbon-based catalysts fully sourced from biomass. The development of such materials plays a crucial role in advancing sustainable catalyst design while fostering a circular economy through the effective utilization of agro-industrial waste. Furthermore, only a limited number of studies have focused solely on biomass-derived materials, and among those, their catalytic performance rarely exceeds the results demonstrated in this work.