Nanoconfined Synthesis of Nitrogen-Rich Metal-Free Mesoporous Carbon Nitride Electrocatalyst for the Oxygen Evolution Reaction
Md A. Wahab, Jickson Joseph, Luqman Atanda, Ummul K. Sultana, Jorge Beltramini, Kostya Ostrikov, Geoffrey Will, Anthony P. O’Mullane, Ahmed Abdala
Abstract
Synthesizing metal-free, low-cost, and durable electrocatalysts that are active for the oxygen evolution reaction (OER) is essential for the development of commercial alkaline water electrolyzers. Herein, we develop a nanoconfined synthesis approach for the fabrication of a metal-free graphitic mesoporous carbon nitride (gMesoCN) electrocatalyst with a high surface area of 406 m2/g and high nitrogen content of 48%. This is achieved by a nanohard-templating approach through simple polymerization of guanidine hydrochloride (GndCl) as a single carbon–nitrogen source inside the organized mesopore channels of a mesoporous SBA15 silica nanotemplate. The produced material is characterized with X-ray diffraction (XRD) and transmission electron microscopy (TEM), which confirmed the formation of a well-ordered mesoporous carbon nitride, while analysis of the pore size distribution indicated the formation of uniformly sized pore channels of 4.56 nm. X-ray photoelectron spectroscopy (XPS) indicated that gMesoCN consisted of C and N. The metal-free gMesoCN material showed good electrocatalytic performance for the OER in alkaline medium, where a Tafel slope of 52.4 mV/dec indicated favorable OER kinetics. Significantly, the gMesoCN material demonstrates long-term durability with 98.4% retention of current density after 24 h. The reported gMesoCN material is inexpensive, environmentally friendly, and easy-to-synthesize with the potential for applicability in the field of electrocatalysis.