Hierarchical MoS₂ nanosheets on flexible carbon felt as an efficient flow-through electrode for dechlorination

TY - JOUR

T1 - Hierarchical MoS2 nanosheets on flexible carbon felt as an efficient flow-through electrode for dechlorination

AU - Huang, Lizhi

AU - Pedersen, Steen Uttrup

AU - Bjerglund, Emil

AU - Lamagni, Paolo

AU - Glasius, Marianne

AU - Hansen, Hans Christian Bruun

AU - Daasbjerg, Kim

PY - 2017

Y1 - 2017

N2 - MoS 2, a layered transition metal dichalcogenide, is well-known as an efficient catalyst for the hydrogen evolution reaction. For the first time, we show that MoS 2 is also a promising electrocatalyst for reductive dehalogenation of chloro-substituted carboxylic acids in water. MoS 2 nanosheets were grown directly on flexible/soft carbon felt using a facile hydrothermal method. The MoS 2 nanosheet loaded carbon felt was used as flow-through electrode for reductive dechlorination of trichloroacetic acid under environmentally relevant conditions resulting in a much more efficient process than using metal electrodes. Atomic hydrogen produced from water reduction at the MoS 2 surface can be exploited to accomplish a complete dehalogenation, yet with a dramatic drop in the Faradaic efficiency due to the concomitant dihydrogen evolution. Doping of the MoS 2 catalyst with transition metals resulted in an increase in the Faradaic efficiency as well as the complete dechlorination of trichloroacetic acid to acetic acid. The edge sites of MoS 2 are believed to be responsible for the indirect dechlorination involving atomic hydrogen. With the cobalt doped MoS 2 catalyst, 100% full dechlorination was accomplished at an applied potential of -1.1 V vs. Ag/AgCl using a flow rate of 1 mL min -1. The catalyst synthesis, electrode preparation, and setup of the electrochemical flow cell are straightforward and readily up-scaled, demonstrating the potential of this methodology in practical applications.

AB - MoS 2, a layered transition metal dichalcogenide, is well-known as an efficient catalyst for the hydrogen evolution reaction. For the first time, we show that MoS 2 is also a promising electrocatalyst for reductive dehalogenation of chloro-substituted carboxylic acids in water. MoS 2 nanosheets were grown directly on flexible/soft carbon felt using a facile hydrothermal method. The MoS 2 nanosheet loaded carbon felt was used as flow-through electrode for reductive dechlorination of trichloroacetic acid under environmentally relevant conditions resulting in a much more efficient process than using metal electrodes. Atomic hydrogen produced from water reduction at the MoS 2 surface can be exploited to accomplish a complete dehalogenation, yet with a dramatic drop in the Faradaic efficiency due to the concomitant dihydrogen evolution. Doping of the MoS 2 catalyst with transition metals resulted in an increase in the Faradaic efficiency as well as the complete dechlorination of trichloroacetic acid to acetic acid. The edge sites of MoS 2 are believed to be responsible for the indirect dechlorination involving atomic hydrogen. With the cobalt doped MoS 2 catalyst, 100% full dechlorination was accomplished at an applied potential of -1.1 V vs. Ag/AgCl using a flow rate of 1 mL min -1. The catalyst synthesis, electrode preparation, and setup of the electrochemical flow cell are straightforward and readily up-scaled, demonstrating the potential of this methodology in practical applications.

U2 - 10.1039/c7en00925a

DO - 10.1039/c7en00925a

M3 - Journal article

SN - 2051-8153

VL - 4

SP - 2286

EP - 2296

JO - Environmental Science: Nano

JF - Environmental Science: Nano

IS - 12

ER -