Sulfonated carbon–based heterogeneous acid catalysts in direct biomass redox flow fuel cell: A review

This review focused on the potential applications of sulfonated carbon–based heterogeneous acid catalysts for the hydrolysis of lignocellulosic biomass (LCB) fuel feedstock and the development of membrane electrode assembly (MEA) for the direct biomass redox flow fuel cell (DBRFFC). LCBs are hydrolysed to yield simple sugars, which are subsequently oxidized over catalysts in the anode tank of the DBRFFC to generate electricity. Ferric chloride used as a catalyst in the DBRFFC is not efficient for glucose production from LCB, such that the power performance of the DBRFFC is affected during glucose oxidation due to low glucose yield from LCB for electron generation. Sulfonated carbon–based solid acid catalysts (SCSACs) have been established as efficient catalysts for the hydrolysis of LCB and as metal catalyst supports for the fabrication of MEA for further oxidation of glucose and its oxidation by‐products. These capabilities of SCSACs can be explored and applied to significantly improve the power output of the DBRFFC through efficient hybrid catalyst design. There is still a scarcity of literature on this subject and their combination with ferric chloride to enhance glucose yield and oxidation in DBRFFC. This gap was filled by discussing the various types of sulfonated carbon–based catalysts, highlighting their synthesis routes, and their applications in organic compound synthesis, and membrane electrode development in DBRFFC. The knowledge derived will certainly be beneficial to researchers willing to improve the performance of DBRFFC through molecular catalyst design and electrode membrane development for application in DBRFFC.