Synthesis of Metal-Free Nanoporous Carbon with Few-Layer Graphene Electrocatalyst for Electrochemical NO2- Oxidation

Herein, electrochemical oxidation of nitrite (NO2-) is demonstrated using metal-free and electrochemically highly stable nanoporous carbon (NC) system. The surface features of nanoporous carbon were studied using both spectroscopic and microscopic techniques including scanning electron microscope (SEM), transmission electron microscope (TEM) and is having layered mesh-like features with a particle size of similar to 20 to similar to 100 nm. The as-synthesized electrocatalyst is found to be more active towards electrooxidation of nitrite (NO2-) at considerably low onset potential of 0.58 V vs SCE with a significantly high current density of 5.2 mu A/cm(2) determined from linear sweep voltammetry (LSV), and cyclic voltammetry (CV) studies. The concentration and scan rate dependent studies confirm the nitrite oxidation is diffusion-controlled process. The interfacial electron transfer features and parameters involved are determined by electrochemical impedance spectroscopic (EIS) studies. Moreover, current stability at a nitrite oxidation (0.58 V vs SCE) potential is also tested by chronoamperometric (i-t) measurements and it demonstrates nanoporous carbon is having long term electrochemical stability. These studies establish the metal-free nanoporous carbon as an efficient electrocatalyst for nitrite oxidation and will be good futuristic electrode material for other energy and environmental based electrochemical monitoring studies.