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

• Published in: Scientific reports 2017-07, Vol.7 (1), p.5142-9, Article 5142
• Main Authors: Xu, Fan, Li, Huan, Liu, Yueling, Jing, Qi
• Format: Article
• Language: English
• Subjects: 639/4077/893; 639/4077/909/4053; Carbohydrates; Carbon dioxide; Cellulose; Electricity; Electron transfer; Ferric chloride; Fuel cells; Fuel technology; Glucose; Humanities and Social Sciences; multidisciplinary; Oxidation; Science; Science (multidisciplinary); Starch
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-05535-2

Liquid catalyzed fuel cell (LCFC) is a kind of redox flow fuel cell directly converting carbohydrates to electricity. To improve its efficiency, ferric chloride (FeCl 3 ) was introduced as main catalyst. As mono catalyst, phosphomolybdic acid (PMo 12 ) was much better than phosphotungstic acid (PW 12 ) and FeCl 3 was intermediate between them. Compared with PMo 12 at the optimal dose of 0.30 mol/L, the combination of FeCl 3 (1.00 mol/L) and PW 12 (0.06 mol/L) achieved similar power output from glucose (2.59 mW/cm 2 ) or starch (1.57 mW/cm 2 ), and even improved the maximum power density by 57% from 0.46 to 0.72 mW/cm 2 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 FeCl 3 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 FeCl 3 reduced the usage of polyoxometalates by 80%, and the replacement implied that LCFC can be operated less toxically and more economically.