Phosphomolybdic acid was investigated as a mediator for indirect carbon electrooxidation at low temperatures. Linear sweeping voltammetry and chronoamperometry experiments showed that the carbon electrooxidation process was influenced by the type of carbonaceous material, reaction conditions, reaction time, and phosphomolybdic acid concentration. The mechanism underlying indirect carbon electrooxidation was explored using cyclic voltammetry. The results showed that the reactivity of coconut-derived activated carbon was higher than that of coal-derived activated carbon or coal in the chemical reaction between phosphomolybdic acid and carbon materials. Sunlight and heating to 80℃ similarly improved the efficiency of the indirect carbon electrooxidation. The electrooxidation mechanism is as follows:MoVI in phosphomolybdic oxidizes carbon to form MoV, and is then electrooxidized back to MoVI in an anodic reaction, releasing the electron obtained from the carbon material. This process facilitated the indirect electrooxidation of carbon at low temperatures. Sunlight was found to enhance the rate of the chemical reaction between phosphomolybdic acid and carbon materials in two ways:1) thermally by increasing the reaction temperature and thus improving the reaction rate; 2) photocatalytically, as sunlight absorbed by phosphomolybdic acid is converted into chemical energy, which is the main effect. A full cell test with phosphomolybdic acid demonstrated a power density of 0.087 mW·cm-2 at room temperature, indicating that the concept of low-temperature carbon fuel cells is feasible.
Received: 07 September 2016
Published: 31 October 2016
Fig 1 Color change of PMo12 reacted with different carbon materials (a) the color of PMo12; (b) the color of PMo12 reacted with coconut activated carbon; (c) the color of PMo12 reacted with coal derived activated carbon; (d) the color of PMo12 reacted with coal
Fig 2 Linear sweep voltammogram (LSV) curves (a) and the CA curves (b) of reduced PMo12 reacted at 80 ℃ with different types of carbon materials AC: activated carbon; CA: chronoamperometry
Fig 3 LSV curves of reduced PMo12 with coconut activated carbon at different conditions
Fig 4 Temperature comparison of coconut activated carbon with PMo12 solution and pure PMo12 solution under sunlight
Fig 5 LSV curves of PMo12 reacted with coconut activated carbon in absence and presence of water cool
Fig 6 LSV curves of reduced PMo12 reacted with coconut activated carbon at 80 ℃ after different reaction time The insert is the plot of current density and the reaction time of PMo12 reacted with coconut activated carbon at 80 ℃.
Fig 7 LSV curves of different concentrations of PMo12 reacted with coconut activated carbon The insert is the plot of current density and the concentration of PMo12 reacted with coconut activated carbon at 80 ℃ for 6 h.
Fig 8 Cyclic voltammetry (CV) curves of PMo12 on the carbon cloth
Fig 9 Performance curves of fuel cell with an anolyte of reduced PMo12 and a catholyte of (VO2) 2SO4 at 25 ℃
Cao D. X. ; Sun Y. ; Wang G. L. J. Power Sources 2007, 167, 250.
Kacprzak A. ; Kobylecki R. ; Bis Z. J. Power Sources 2013, 239, 409.
Kacprzak A. ; Koby?ecki R. ; W?odarczyk R. ; Bis Z. J. Power Sources 2014, 255, 179.
Wang C. Q. ; Liu J. ; Zeng J. ; Yin J. L. ; Wang G. L. ; Cao D. X. J. Power Sources 2013, 233, 244.
Liu J. ; Ye K. ; Zeng J. ; Wang G. L. ; Yin J. L. ; Cao D. X. Electrochem. Commun. 2014, 38, 12.
Rady A. C. ; Gibbdey S. ; Kulkarni A. ; Badwal S. P. S. ; Bhattacharya S. ; Ladewig B. P. Appl. Energy 2014, 120, 56.
Kularni A. ; Giddey S. ; Badwal S. P. S. ; Paul G. Electrochim. Acta 2014, 121, 34.
Xu X. Y. ; Zhou W. ; Liang F. L. ; Zhu Z. H. Appl. Energy 2013, 108, 402.
Elleuch A. ; Yu J. S. ; Boussetta A. ; Halouani K. ; Li Y. D. Int. J. Hydrog. Energy 2013, 38, 8514.
Weibel D. B. ; Boulatov R. ; Lee A. ; Ferrigno R. ; Whitesides G. M. Angew. Chem. Int. Ed. 2005, 44, 5682.
Paraknowitsch J. P. ; Thomas A. ; Antonietti M. Chem. Mater. 2009, 21, 1170.
Kozhevnikov I. V. Chem. Rev. 1998, 98, 171.
Subba Reddy B. V. ; Narasimhulu G. ; Subba Lakshumma P. ; Vikram Reddy Y. ; Yadav J. S. Tetrahedron Lett. 2012, 53 (14), 1776.
Yadav J. S. ; Satyanarayana M. ; Balanarsaiah E. ; Raghavendra S. Tetrahedron Lett. 2006, 47 (34), 6095.
Wang B. ; Zhang J. ; Zou X. ; Dong H. G. ; Yao P. P. Chem. Eng. J. 2015, 260, 172.
Song X. J. ; Zhu W. C. ; Yan Y. ; Gao H. C. ; Gao W. X. ; Zhang W. X. ; Jia M. J. J. Mol. Catal. A: Chem. 2016, 413, 32.
Kendell S. M. ; Brown T. C. ; Burns R. C. Catal. Today 2008, 131 (1-4), 526.
Gao Y. Z. ; Syed J. A. ; Lu H. B. ; Meng X. K. Appl. Surf. Sci. A 2016, 360, 389.
Martínez-Morlanes M. J. ; Martos A. M. ; Várez A. ; Levenfeld B. J. Membr. Sci. 2015, 492, 371.
Gómez-Romero P. ; Asensio J. A. ; Borrós S. Electrochim. Acta 2005, 50 (24), 4715.
Sauk J. ; Byun J. ; Kim H. J. Power Sources 2005, 143 (1-2), 136.
Guo X. ; Guo D. J. ; Wang J. S. ; Qiu X. P. ; Chen L. Q. ; Zhu W. T. J. Electroanal. Chem. 2010, 638 (1), 167.
Zhu M. Y. ; Gao X. L. ; Luo G. Q. ; Dai B. J. Power Sources 2013, 225, 27.
Jin X. L. ; He B. ; Miao J. G. ; Yuan J. H. ; Zhang Q. X. ; Niu L. Carbon 2012, 50 (8), 3083.
Dong Q. ; Wang X. Y. ; Lu Y. M. ; Sun H. Y. ; Meng Q. L. ; Liu S. L. ; Feng W. ; Han X. K. J. Mol. Struct. 2014, 1075, 154.
He T. ; Yao J. Progress in Materials Science 2006, 51, 810.
Liu W. ; Mu W. ; Liu M. ; Zhang X. ; Cai H. ; Deng Y. Nat. Commun. 2014, 5, 3208.
Yamase T. Chem. Rev. 1998, 98, 307.
Pham M. C. ; Bouallala S. ; Lé L. A. ; Dang V. M. ; Lacaze P. C. Electrochim. Acta 1997, 42 (3), 439.
Sun C. Q. ; Zhang J. D. Electrochim. Acta 1998, 43 (8), 943.
Wang, Y. Q. Study of Methanol Oxidation on Pt-Au Electrode Enhanced by Phosphomolybdic Acid. M. S. Dissertation, Chongqing University, Chongqing, 2007.
王耀琼. Pt-Au电极上磷钼酸增强甲醇电化学氧化的研究[D].重庆:重庆大学, 2007.
Zhang, H. B.; Wu, T. H.; Yan, X. B.; Leng, Y. C.; Li, S. J. Chem. J. Chin. Univ. 1990, 11 (10), 1096.