121st General Meeting of the KCS

Type Poster Presentation
Area Physical Chemistry
Room No. Event Hall
Time 4월 20일 (금요일) 11:00~12:30
Code PHYS.P-97
Subject A Metal-free Bifunctional Electrocatalysts for OER/ORR in Alkaline Media: From Mechanisms to Structure-activity relationship
Authors chiho lee, EUN BI NAM1, Sang Uck Lee*
Department of Bio-Nano Engineering, Hanyang University, Korea
1Hanyang University, Korea
Abstract In the recent years, water splitting has attracted substantial interest including key processes oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in renewable energy conversion and storage devices such as the cathode of fuel cells, metal-air batteries and supercapacity. Here we designed C3N4 and C2N structures doped with heteroatoms, P, S or PS, as outstanding electrocatalysts for following key reactions by performing density functional theory (DFT) calculation in alkaline environment, considering the possible reaction pathways based on the Eley-Rideal (ER) mechanism as well as the doping effects on electrocatalytic activity. In this work, the relative stability of O* and OOH* intermediates was a key factor determining the ORR pathway; accordingly, ORR follows a two-step reaction pathway governed by O* rather than a four-step reaction pathway governed by OOH*. In addition, we found that P, S co-doped C3N4 shows superior OER/ORR activity with synergistic geometric and electronic effects, which coordinatively increase unsaturated sp3-C via structural deformation and improve electrical conductance by modulating the electronic structure with extra electrons from dopants. In particular, PCSC-C3N4 (C3N4 with P and S co-doped at the carbon site) and SN-C2N show better bifunctional performance of OER/ORR with competitive overpotentials at 0.42 V/0.27 V (PCSC-C3N4) and 0.40 V/0.14 V (SN-C2N), respectively, compared to conventional Pt and RuO2 catalysts.
E-mail holee@cms.hanyang.ac.kr