Augmenting reaction rates on porous carbon electrodes is critical for reducing the cost of all-vanadium redox flow batteries (VRFBs). To this end, reduced graphene oxide (rGO) based carbons hold promise, demonstrating high specific surface area, chemomechanical stability, and electrochemical activity. While initial efforts have shown that rGOs can enhance VRFB performance, the range of unique processing conditions leads to a collection of materials with disparate elemental composition and porous structure, thus obscuring performance-determining characteristics behind redox reactions and frustrating general design principles. Here, we generate rGO electrocatalysts of nearly identical chemical composition but different textures (i.e., surface area and pore structure) by varying the drying step in the graphene synthesis (i.e., vacuum-drying vs. carbon dioxide critical point drying). We apply spectroscopic and electrochemical techniques on the synthesized rGOs, observing a three-fold increase in BET surface area using critical point drying. We subsequently decorate carbon felt electrodes – both pristine and thermally activated – with rGO microparticles via a flow deposition procedure, and evaluate their performance and durability in a VRFB cell. The synthesis approach and findings described in this work inform and complement efforts to advance the material science and engineering of rGO electrocatalysts.
Bibliographical noteKAUST Repository Item: Exported on 2022-03-17
Acknowledgements: A.A. gratefully acknowledges support from the KACST-MIT Ibn Khaldun Fellowship for Saudi Arabian Women. Research by C.T.W. and F.R.B. was supported by the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. C.T.W. acknowledges a graduate fellowship through the National Science Foundation Graduate Research Fellowship Program under Grant No. 1122374. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. The authors thank Christopher Mallia, Bertrand Neyhouse, and Katelyn Ripley for their insightful feedback on the manuscript. Finally, this manuscript makes use of equipment in MIT's Center for Materials Science and Engineering Shared Experimental Facilities, supported in part by the MRSEC Program of the National Science Foundation under award number DMR1419807.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering