Electrocatalytic oxidation of formaldehyde using pencil graphite electrode modified with layer-by-layer electrodeposition of carbon dots/polypectin/cobalt nanoparticles

Abstract

The development of non-noble metal-based catalysts with high electrocatalytic activity and minimal poisoning for the oxidation of small organic molecules is of vital importance in the energy world. In the present work, carbon dots (CDs) and polypectin (PPC) were electrochemically synthesized and deposited on pencil graphite electrodes (PGE) to create unique multifunctional PPC/CD/PGE. Co nanoparticles (CoNPs) were subsequently electrodeposited on PPC/CDs, leading to the fabrication of CoNPs/PPC/CDs/PGE. The nanostructure nature of electrode modifier was characterized by various techniques. The electrocatalytic performance of CoNPs/PPC/CDs/PGE for the electrooxidation of formaldehyde in alkaline medium was investigated using different electrochemical methods. Based on the electrochemical results, the modified electrode showed excellent electrocatalytic activity for formaldehyde oxidation with minimum onset potential (−0.020 V/SCE) and high current density (35 mA cm⁻²) compared to other reported nanocatalysts based on noble (platinum group) and non-noble metals through an electrochemical-chemical (EC′) pathway. The electrochemical behavior of CoNPs/PPC/CDs/PGE in the presence of formaldehyde showed that the incorporation of CoNPs in the PPC/CD nanocomposite prepared on PGE significantly increases the electrocatalytic activity of the direct oxidation of formaldehyde, which can promise a new strategy in order to design cobalt-based high performance nanoelectrocatalysts for formaldehyde fuel cells.