Advanced redox flow fuel cell using ferric chloride as main catalyst for complete conversion from carbohydrates to electricity

Abstract

Liquid catalyzed fuel cell (LCFC) is a kind of redox flow fuel cell directly converting carbohydrates to electricity. To improve its efficiency, ferric chloride (FeCl3) was introduced as main catalyst. As mono catalyst, phosphomolybdic acid (PMo12) was much better than phosphotungstic acid (PW12) and FeCl3 was intermediate between them. Compared with PMo12 at the optimal dose of 0.30 mol/L, the combination of FeCl3 (1.00 mol/L) and PW12 (0.06 mol/L) achieved similar power output from glucose (2.59 mW/cm2) or starch (1.57 mW/cm2), and even improved the maximum power density by 57% from 0.46 to 0.72 mW/cm2 when using cellulose as the fuel. Long-term continuous operation of the LCFC indicated that carbohydrates can be hydrolyzed to glucose and then oxidized stepwise to carbon dioxide. At the latter stage, there was a linear relationship between the electron transfer number from glucose to catalyst and the subsequent cell performance. Based on these findings, the contribution of FeCl3 to LCFC should be derived from the accelerated hydrolysis and oxidation of carbohydrates and the enhanced electron transfer from glucose to anode. The addition of FeCl3 reduced the usage of polyoxometalates by 80%, and the replacement implied that LCFC can be operated less toxically and more economically.

Electricity generation from food wastes and spent animal beddings with nutrients recirculation in catalytic fuel cell

“…The use of glucose as fuel yielded very high power densities of 6.7 mW/cm 2 . This value is very similar but slightly higher than obtained via the use of glucose in previous studies 40,51 which utilized the same co-catalysts as used in the current study. In the usage of starch as fuel in the cell, the power density reached 2.1 mW/cm 2 which was far lower than the result obtained in the use of glucose since starch showed a lower level of catalytic reactions than glucose in the fuel cell.…”

“…In this study, the fermentation liquids from FW and SAB generated mean open-circuit voltages of 0.64 and 0.53 V and P mean of 1.6 and 1.3 mW/cm 2 respectively.. In reality, FW fuel has a higher power density than the value (1.2 mW/cm 2 ) obtained by Liu et al 51 but lower than the 3.4 mW/cm 2 reported by Xu et al 40 when glucose was used as fuel. Interestingly, SAB fuel also performed better than the earlier report for FW 51 .…”

“…Mono treatment of fW and SAB organic components. As earlier reported 40 , one way to confirm the efficiency of a fuel cell in converting the organic constituents of FW was to directly and singly treat the major components and this further showed the extent of degradation or utilization of each component in the fermentation liquid and the extent of contribution toward the overall electricity generation from the cell. Even though this was reported for FW in that previous study, there is a need to do the same for the major constituents of SAB which are not very different from those of FW.…”

“…23.4 and 20.9 g/L for FW and SAB respectively 59,60 . However, these are still far lower than the 180 g/L glucose concentration used in the study of Xu et al 40 which yielded a better result. In the use of fermentation liquid for fuel cell therefore, a higher concentration of the liquid is required to enhance the performance efficiency.…”

“…The fuel cell used in this study is very similar to the one earlier described 40 . The structure consists of two chambers i.e.…”