A method of use of a direct isopropanol fuel cell, comprising: providing a direct fuel cell comprising: a proton conducting or exchange membrane with a cathode side and an anode side, a cathode having a cathode catalyst on the cathode side of the membrane and an anode having an anode catalyst on the anode side of the membrane such that the membrane is arranged between the cathode and the anode, operating the direct fuel cell to generate electricity by supplying the anode with a liquid fuel and supplying the cathode with atmospheric air from the atmosphere containing oxygen; characterized by: the cathode is open to the atmosphere placing the cathode side of the membrane passively in communication with the atmosphere, the membrane comprising a sulfonated poly(aryl ketone) membrane, the anode catalyst is selected from the group of a platinum and ruthenium catalyst, a platinum and nickel catalyst, a platinum and gold catalyst, and mixtures thereof, the cathode catalyst comprises a platinum catalyst, the liquid fuel consisting of 10% to 90% by volume isopropanol, 90% to 10% by volume water and 0% to 30% by volume acetone in contact with the anode catalyst on the anode side of the membrane,operating the fuel cell at electrical potentials between the anode and the cathode such that a reaction at the anode catalyst to oxidize a molecule of isopropanol into a molecule of acetone releasing two electrons is a principal reaction, and the membrane selected to permit the acetone at the anode catalyst to pass through the membrane to the cathode side of the membrane into communication with the atmosphere, the acetone at the anode catalyst passing through the membrane to the cathode side of the membrane into communication with the atmosphere and evaporating into the atmosphere at the cathode side of the membrane. a proton conducting or exchange membrane with a cathode side and an anode side, a cathode having a cathode catalyst on the cathode side of the membrane and an anode having an anode catalyst on the anode side of the membrane such that the membrane is arranged between the cathode and the anode, operating the direct fuel cell to generate electricity by supplying the anode with a liquid fuel and supplying the cathode with atmospheric air from the atmosphere containing oxygen; characterized by: the cathode is open to the atmosphere placing the cathode side of the membrane passively in communication with the atmosphere, the membrane comprising a sulfonated poly(aryl ketone) membrane, the anode catalyst is selected from the group of a platinum and ruthenium catalyst, a platinum and nickel catalyst, a platinum and gold catalyst, and mixtures thereof, the cathode catalyst comprises a platinum catalyst, the liquid fuel consisting of 10% to 90% by volume isopropanol, 90% to 10% by volume water and 0% to 30% by volume acetone in contact with the anode catalyst on the anode side of the membrane,operating the fuel cell at electrical potentials between the anode and the cathode such that a reaction at the anode catalyst to oxidize a molecule of isopropanol into a molecule of acetone releasing two electrons is a principal reaction, and the membrane selected to permit the acetone at the anode catalyst to pass through the membrane to the cathode side of the membrane into communication with the atmosphere, the acetone at the anode catalyst passing through the membrane to the cathode side of the membrane into communication with the atmosphere and evaporating into the atmosphere at the cathode side of the membrane.