Boosting the electrocatalytic performance of carbon nanotubes toward V(V)/V(IV) reaction by sulfonation treatment

Abstract

Summary Carbon nanotubes (CNTs) were modified by hydrothermal treatment by using chlorosulfonic acid and studied as electrocatalyst for V(V)/V(IV) reaction in vanadium redox flow battery. After treatment, CNTs were functionalized with many sulfonic groups, no causing obvious change for the morphology. Contact angle measurements confirm the improvement of wettability of sulfonated CNTs. The introduced sulfonic groups act as active sites and also result in more defects. As a result, the electrocatalytic properties of CNTs toward V(V)/V(IV) reaction are dramatically enhanced by sulfonation treatment. Among sulfonated CNTs, the sample treated for 10 hours (CNT‐S10) shows the highest electrocatalytic properties. The cell employing CNT‐S10 as positive electrocatalyst was assembled, and the performances were assessed. The cell using CNT‐S10 exhibits better electrochemical properties, including cycling and rate performance. The energy efficiency of the cell increases by 4.9% by using CNT‐S10 electrocatalyst. The excellent electrocatalytic properties of sulfonated CNTs are mainly attributed to the dramatical improvement of hydrophilicity of CNTs and introduction of sulfonic groups as active sites, correspondingly enhancing the mass transfer performance and electrochemical activity toward V(V)/V(IV) reaction. Our study reveals that sulfonated CNTs are a promising and efficient positive electrocatalyst for vanadium redox flow battery.

A green approach to fabricate binder‐free S‐doped graphene oxide electrodes for vanadium redox battery

“…Table 3 showed the parameters obtained through the simulation of the plots with the corresponding ECM. R s for S‐GOEs slightly fluctuated, which can be related to the sum of resistance to the hydrophilicity of electrode surfaces, impurities and even connection elements of device 4,14 . The R ct for modified electrodes was much lower than that of the PGE (Table 3).…”

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

“…Hydrothermal sulfonation of CNTs was suggested by He et al [378]. Enhanced wettability but unchanged morphology were observed.…”

Characterization of Carbon Felt Electrodes for Vanadium Redox Flow Batteries: Impact of Treatment Methods

“…These include improved felt design, [10][11][12][13] compression, [14][15][16] as well as surface modifications, which either increase the surface area, [17][18][19][20][21] or introduce functional groups [22][23][24][25][26][27][28] or supporting catalysts, such as metals 29,30 or metal oxides. [31][32][33] So far, the most practical and common treatment method is a thermal treatment, where the electrode surface is oxidized in an air atmosphere for up to 30 h at 400 • C. [34][35][36] Although most publications are focusing on one carbon felt or paper type and their modification, the precursor was found to influence the catalytic activity of the electrode.…”