PEDOT: PSS-MWCNTs modified carbon black-based gas diffusion electrodes for improved performance of in-situ electrocatalytic flue gas desulfurization

In-situ electrocatalytic flue gas desulfurization (FGD) using a carbon black (CB)-based gas diffusion electrode (GDE) is efficient with no secondary pollution. However, higher desulfurization efficiency and energy conservation are demanded. In this work, CB-based GDEs were modified with poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate)-multi-walled carbon nanotubes (PEDOT: PSS-MWCNTs) for H2O2 production from two-electron oxygen reduction reaction (2e-ORR) during in-situ FGD. The results showed that the GDE modified with 100 mg 5% PEDOT: PSS-MWCNTs obtained the highest desulfurization efficiency (100.0%) and the lowest energy consumption (1.07 kW h kg−1), as 2e-ORR efficiency is improved from balancing ORR catalysis, pore structure, hydrophilicity, conductivity of the GDE, and the noncovalent interaction between MWCNTs and PEDOT: PSS. While excess PEDOT: PSS in the PEDOT: PSS-MWCNTs composite would cause reduced total pore area and porosity and excessive hydrophily which is harmful to O2 transfer for the GDE, hindering the 2e-ORR and desulfurization. This compact in-situ FGD system has advantages in desulfurization efficiency, energy consumption and durability, showing great potential in future industrial application.