| Microbial fuel cell(MFC) technology can directly convert the chemical energy of organic contaminants to electricity. This technology has been paid high attention due to its two major advantages: sewage treatment and power generation. Air cathode microbial fuel cell can directly use the oxygen in the air and produce water. Therefore, it is hopeful to realize large-scale application of MFC. However, the activation energy of oxygen reduction reaction(ORR) is very high, and the MFC performance is commonly governed by cathode ORR catalyst. Platinum(Pt) has been widely used as the cathodic catalyst, because it can reduce the cathodic reaction activation energy and increase the reaction rate. However, the high cost, limited supply and sensitivity to poisoning limited its application in MFCs. Therefore, it is an effective way to solve this problem by developing cheap and efficient cathode catalyst.In this research, in order to reduce the cost of noble metal platinum catalyst of MFC and improve the performance of cathode ORR, PtSnP and PtSnCo catalysts were designed and synthesized. And the morphology, surface composition and ORR properties of the catalysts were studied by means of various characterization methods. The new ternary platinum based alloys were applied in the MFC as the cathode catalyst firstly. Moreover, the advantages and application potential of the power generation and wastewater treatment were discussed in detail. Innovative research results were achieved in this paper. The specific research results were as follows:(1) The oxygen reduction reaction activity and power generation property of the ternary PtSnP/C and binary PtSn/C catalysts were synthesized and investigated. The cyclic voltammogram(CV) analyses showed that phosphorus remarkably improved the oxygen reduction reaction, with the oxygen reduction peak at 0.183 V for Pt7Sn3P/C, versus 0.171 V for Pt/C. The characterization results of transmission electron microscopy(TEM) and X-ray powder diffraction(XRD) showed that the excellent ORR activity of Pt7Sn3P/C was attributed to the smaller metal particle size(1.58 nm) and uniform size distribution. The characterization results of X-ray photoelectron spectroscopy(XPS) confirmed the effect of phosphorus on the surface structure and the promoting effect of d band center migration of the Pt atom. In addition, among three PtSn/C catalysts with different Pt/Sn molar ratios(Pt7Sn3/C, Pt5Sn5/C and Pt3Sn7/C), Pt7Sn3/C showed the highest ORR catalytic activity, even better than Pt/C, indicating that the content of Sn had a significant effect on the catalytic behavior. The maximum power density(361 mWm-2) of MFC with Pt7Sn3P/C cathode was the highest among all the prepared catalysts, followed by Pt7Sn3/C(336 mWm-2) and Pt/C(307 mWm-2).(2)The oxygen reduction reaction activity and power generation property of the ternary PtSnCo/C catalyst was investigated. It was found that all the catalysts had nanosized particles with narrow size distribution. Moreover, due to the addition of other metals in the alloy catalysts, the lattice parameter of Pt had been changed. Pt lattice parameter increased with the addition of Sn while decreased with the addition of Co so that it showed no significant change with the codeposition of the proper amounts of Sn and Co. The results of CV showed that the oxygen reduction peak potential of Pt7Sn2Co/C catalyst was 0.221 V, which was much larger than that of Pt/C(0.182 V). The order of MFC maximum power density was as follows: Pt7Sn2Co/C > Pt7Sn3/C > Pt/C > Pt7Co3/C. The MFC with Pt7Sn2Co/C cathode catalyst obtained the maximum power density(456 mW/m2), which was increased by 19% compared with that of Pt/C. Pt7Sn2Co/C was identified as a more suitable cathode catalyst for MFC because of low cost, good stability and high activity. |
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