A bifunctional two dimensional TM3(HHTP)2 monolayer and its variations for oxygen electrode reactions

Abstract

To achieve renewable energy technologies, low-cost electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are required to replace Pt and IrO₂/RuO₂ catalysts. Based on density functional theory, the catalytic activity of TM₃(HHTP)₂ (2,3,6,7,10,11-hexahydroxytriphenylene) monolayer and its variations (TMX₄, where TM = Fe, Co, Ni, X = O, S, Se) for bifunctional ORR/OER have been investigated. The adsorption ability is dominated by the metal center, in the order of Fe > Co > Ni while the ligand shows the minor contribution. Due to the presence of linear relations between the intermediates, the activity of TMX₄ for the ORR/OER follows a dual volcano curve as a function of the OH adsorption strength. Considering the overpotential, CoO₄ and CoS₄ possess superior bifunctional activity, implying their promise as candidates for the oxygen electrode reaction. This systematical work may open new avenues for the development of high-performance non-PGM catalysts for practical applications of ORR and OER.