This review focused on the progress catalysts, redox couples, mediators and oxidants have made in the power generation of

direct biomass redox fl ow fuel cell (DBRFFC), identifying the challenges associated with them, and the approach toward

resolving the issues to improve the power output of the direct biomass redox fl ow fuel cell. Ferric chloride and polyoxometalates

currently used as catalysts with some redox couples, mediators, and oxidants provide less than 10% of the total harvestable

electrons from the biomass degradation for power generation in DBRFFC. They are also inorganic toxic non-renewable

catalysts that do not selectively break down the biomasses completely into simple reducing sugars for further oxidation into

carbon dioxide and water only during electricity generation in the cell. By-products are produced which trap more electrons

that would have been released for improved power generation if complete biomass oxidation were achieved. This challenge

can be addressed by developing and combining organic catalyst with less quantity of the inorganic ones for more effi cient

biomass hydrolysis and oxidation. This review discussed biomass degradation in DBRFFC by thermo-chemical and photochemical

means and the performances that have been achieved with the catalysts, redox couples, mediators and oxidants

that were applied. Drawing from the knowledge will shape the future research direction toward reducing the usage of the

non-renewable catalysts by designing and developing effi cient renewable catalysts that can act in synergy with the inorganic

ones for the biomass hydrolysis and oxidation for improved power generation of the DBRFFC.