A Membraneless Direct Isopropanol Fuel Cell (DIPAFC) Operated with a Catalyst-Selective Principle

The concept of catalyst-selective membraneless direct liquid fuel cell (DLFC) has recently been proposed and has successfully been demonstrated with a number of alcohol or formate fuels. However, there is a critical anolyte-poisoning issue in the previous membraneless alkaline DLFC systems due to CO, formation upon the oxidation of liquid fuels. This study demonstrates a new membraneless DLFC system with isopropanol as an anode fuel. The dehydrogenation of isopropanol generates mainly acetone rather than CO, as a product, which eliminates the CO2-poisoning concerns. Operation of the membraneless direct isopropanol fuel cells (DIPAFCs) is principally based on the high catalytic selectivity of the cathode catalyst which exhibits high catalytic activity for the oxygen reduction reaction (ORR) but no activity for the isopropanol oxidation reaction (IPAOR). The highly selective cathode catalysts demonstrated in this study are spinel MnCo2O4 or MnNiCoO4 oxide nanoparticles coupled to a multiwall carbon nanotube (MWCNT) surface. Experimental results reveal that the MnNiCoO4/MWCNT catalyst exhibits a higher ORR activity than the MnCo2O4/MWCNT catalyst. Computational studies based on density functional theory (DFT) indicates that the addition of Ni to MnCo2O4 improves the electrical conductivity of the metal oxide nanoparticles, thereby enhancing the ORR activity of MnNiCoO4/MWCNT. The membraneless DIPAFC demonstrated in this study can deliver a high power density of about 20 mW cm(-2) at room temperature and about 80 mW cm(-2) at 80 degrees C.