Activating a ceria-doped carbon nitride for elemental mercury adsorption by constructing a heterojunction interface: A DFT guided experimental study

Abstract

Engineering sorbent microstructure to regulate their interfacial activity is a promising strategy for enhancing mercury adsorption activity. In this work, carbon nitride microsphere (CNS) synthesized via a hydrothermal route is used for Hg0 adsorption. Bare CNS shows a moderate Hg0 capture performance with mercury removal efficiency of 43.1%. To accomplish effective mercury capture by CNS, the heterojunction structure is rationally developed via density functional theory (DFT). Calculation results reveal a considerable charge interaction at the heterojunction interface of CNS and CeO2. Mercury adsorption energy at the heterojunction interface is significantly higher than that of pristine CNS. xCeO2/CNS composites are prepared by wetness impregnation method under the guidance of DFT results. Optimal performance is observed over 5CeO2/CNS with Hg0 removal efficiency of 98.3%, which testifies that constructing a heterojunction interface can distinctly enhance the mercury capture ability of CNS. These results contribute a lot to the deep understanding of the structural properties and mercury adsorption behaviors of xCeO2/CNS composites, which also indicate that DFT-assisted design of the microstructures of sorbents is a feasible way to improve their mercury removal performances.