the role of nitrogen moieties in n-doped ordered mesoporous carbons for spontaneous and electrochemical grafting of redox active materials

Abstract: ordered mesoporous carbons (omc) have been receiving continues attention for using in electrochemistry in recent years [1]. the unique capabilities of facilitating mass transfer, considerable electrical conductivity, tunable porous channels and high surface area together make them to be suitable candidate materials for fabrication of redox-active electrodes [2]. the chemical and structural properties of omc can be improved by doping different heteroatoms such as nitrogen, phosphorus, sulfur, boron, and multi heteroatoms in their framework as the structure defects in order to enhance the corresponding performance in wither chemical or electrochemical applications. [3, 4]. among heteroatoms, modification of the electrode surface using nitrogen-doped omc has diverse implications in electro-analytical chemistry to fabricate redox-active electrodes with improvement of the electrode/electrolyte interfacial properties [5, 6]. the redox-active electrodes have a wide application in materials science, electroanalytical chemistry, electrocatalysis, biosensing, energy storage, and electronic and optoelectronic systems. the electro-active modified electrodes are constructed via either spontaneous adsorption or electrochemical grafting. in the later, the active redox molecules are covalently bonded to the surface of carboneous materials. the current study mostly deals with the role of nitrogen moieties in omcs for more effective loading of redox active species through both adsorption and electro-grafting protocols. in this direction, a nitrogen-doped omcs bearing high nitrogen content were fabricated by the carbonization of a mixture of ionic liquid (1-methyl-3-phenethyl-1h-imidazolium hydrogen sulfate) and guanine using ordered mesoporous silica sba-15 as hard template. a few electro-active moieties were then used as model to electrochemically functionalize the surface of the resulting n-riched omc. in this way, a redox-active electrode was fabricated via grafting of various electro-active species with different electronic properties onto omcs/gce. our investigation showed that not only the charge on the adjacent carbon atom can markedly influence the surface electro-grafting of redox-active materials, but nitrogen content also exerts a dramatic impact on electrical conductivity, defect site, the electronic nature of the carbons, etc. the mentioned properties enabled us to successfully prepare varied electrodes having different loading of electro-active species on the electrode surface. the outcome of the present work reveals changing the ph of the solution and the nature of substituents on electro-active species leads to significant differences in loading of redox-active molecules.