122nd General Meeting of the KCS

Type Oral Presentation
Area Oral Presentation for Young Scholars in Physical Chemistry
Room No. Room 324A
Time THU 10:24-:
Code PHYS.O-8
Subject Unveiling C1, C2 and C3 mechanism of electrochemical CO2 reduction at sulfur vacancy of MoS2: Ab initio study
Authors Sungwoo Kang, Seungwu Han*
Materials Science and Engineering, Seoul National University, Korea
Abstract MoS2 is receiving large attention as a promising electrochemical carbon dioxide reduction (CO2R) catalyst which shows good selectivity and current density at edge site in ionic liquid [1-3]. Recently, Francis et al. reported that CO2R is occurred at basal plane of MoS2 which produces 1-propanol as a major product [4]. In this work, we investigate the catalytic performance of CO2R at sulfur vacancy (Vs) of MoS2, which has been recently reported as an active site for HER [5], by density functional theory. Possible reaction paths are investigated by modifying computational hydrogen electrode model as considering charged states of intermediates [6]. We first calculated pathways for C1 product: formic acid, formaldehyde, methane and methanol are identified as possible products at potential of -0.4 V vs RHE. In addition, In addition, C2 products (ethanol, ethylene glycol) and C3 products (1-propanol, 1,3-propylene glycol) were possibly evolved at the same potential with C1 products (-0.4 V vs RHE). Our results well explain recent experiment on CO2R at single-crystal and thin film MoS2 electrode that 1-propanol is evolved at -0.59 V vs RHE as a major product. Minor products were produced such as formate, ethylene glycol, t-butanol, methanol and methane at the same potential [4] which was also in agreement with our results. Finally, based on verified mechanism, we suggest cascade structure of Vs-MoS2 with other catalysts, which produces HCHO as a major product, to enhance selectivity of CO2R vs HER at Vs-MoS2. [1] Nat. Commun., 2014, 5, 4470. [2] Science, 2016, 242, 467. [3] ACS Nano, 2018, 11, 453. [4] Chem. Mater., 2018, 30, 4902. [5] Nat. Mater., 2016, 15, 48–53. [6] ACS Catal., 2018, 8, 4508.
E-mail kang1717@snu.ac.kr