High Performance Platinum Group Metal-Free Cathode Catalysts for Microbial Fuel Cell (MFC)

Abstract

The oxygen reduction reaction (ORR) at the cathode is usually the limiting step in microbial fuel cells and improvements have to be done to increase the performances and reduce the cost. For the first time, iron-based catalysts were synthesized utilizing the polymerization-pyrolysis method and tested successfully in neutral media and in working microbial fuel cells (MFCs). The catalysts were synthesized using polymerization, salt formation, mixed with iron salt and pyrolyzed at 850 • C (PABA-850) and 950 • C (PABA-950) respectively. To study the kinetics, electro-activity of the catalysts was investigated using rotating ring disk electrode (RRDE). Results showed that PABA-850 had higher catalytic activity compared to that of PABA-950. Both Fe-catalysts had much better activity compared to activated carbon (AC) used as a baseline. Catalysts were then integrated into air breathing cathodes (loading 1 mg cm −2 ) and tested in single chamber MFC. The power peak obtained was 178 ± 3 μWcm −2 for PABA-850. Comparable power was produced from PABA-950 (173 ± 3 μWcm −2 ). AC power output was 131 ± 4 μWcm −2 that was roughly 40% lower compared to Fe-based catalysts. Those results demonstrated that the addition of platinum group metal free (PGM-free) catalysts increased the output of the MFCs substantially. Fe-based catalysts seem to be suitable for large-scale MFC applications.

Iron-Nicarbazin derived platinum group metal-free electrocatalyst in scalable-size air-breathing cathodes for microbial fuel cells

“…Maximum power density achieved by the Fe-NCB cathode initially was 1.85 W m −2 (day 1) and then decrease by roughly 30% at 1.25 W m −2 after 22 days operations. The maximum power density here reported is comparable to the performance achieved by iron-based catalysts synthesized using the polymerization-pyrolysis method and a catalyst loading of 1 mgcm −2 [ [97] , [98] , [99] ]. The performance are instead slightly lower compared to other reported literature in which the peak of current density was above 2 Wm -2 when Fe-based catalyst was incorporated into the air-breathing cathode structure [ 17 , 18 , 43 , 44 , 47 , 50 , 56 , [67] , [68] , [69] ].…”

Boosting Microbial Fuel Cell Performance by Combining with an External Supercapacitor: An Electrochemical Study

“…[26] Platinum is a very active catalyst, but it is extremely expensive and sensible to poisoning in the presence of anions. [27][28][29][30] Carbonaceous-based materials [31][32][33] and transition metal-containing catalysts [34][35][36][37] have replaced platinum successfully. The addition of transition metals and especially FeÀ NÀ C active sites has improved significantly the performance almost doubling the MFCs output.…”

Influence of platinum group metal-free catalyst synthesis on microbial fuel cell performance

“…Oxygen reduction reaction (ORR) suffers from numerous severe limitations when it occurs in neutral media, and therefore an optimization of the catalyst is needed to accelerate the process [8] , [9] , [10] . First, high activation overpotentials exist, being as high as 50–100 mV when enzymes are utilized [11] , [12] , [13] , [14] , 200–300 mV in the case of platinum based group metal (PGM) catalysts [15] , [16] or platinum group metal-free (PGM-free) catalysts [17] , [18] , [19] , [20] , [21] , [22] , and even larger in the case of bacterial catalyst [23] , [24] , [25] or carbonaceous materials [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] . Second, the ORR reaction kinetics is very slow mainly due to the neutral pH, in which both H + and OH − are present in low concentration and both of them participate directly as reactants of ORR, the first one via the acidic pathway and the second one via the alkaline pathway [5] , [6] , [25] .…”