Voltage and Cation Dependent Electron Storage in Carbon Nitride as Blue K-PHI by Electrochemical Loading

Abstract

The ability of diverse carbon nitride materials to store electrons and develop a blue color through unbalanced consumption of half-charges is well described to occur during photocatalytic reactions. Herein, a similar effect was observed and quantified via electrochemical biasing of a poly(heptazine imide) (PHI)-based electrode in organic media containing various electrolyte species. Thus, by instrumentalizing Faradaic processes in the conduction band of PHI, electron storage is observed, the amount and voltage of which depend on the density of states of the material. Thus, a maximum charge density of 82 C g-1 was achieved after charging the PHI-based electrode for 30 s at an applied potential of -1.9 V versus Ag/Ag+. Notable performance differences arose from screening different organic electrochemical media, mainly influenced by the physicochemical characteristics of chosen cationic species and organic solvent. Our herein contribution describes a novel approach to achieving a bias-dependent chromatic effect of PHI-based materials, with implications in e- accommodation rates and outputs, and potential prospects for electrocatalytic chemical transformations.