Lowering the Pt loading would decrease proton exchange membrane fuel cell (PEMFC) cost, but inevitably increase local oxygen transport resistance and cause performance loss at high current densities. To enhance the local oxygen transport within the catalyst layer, the heat treatment method of the electrode is proposed to regulate ionomer microstructure. After heat-treating the electrode over the ionomer glass-transition temperature, the local oxygen transport resistance decreases and the limiting current density enlarges, which in turn improves the cell performance at high current densities, confirming the enhancement of oxygen transport. Based on the AFM and contact angle test results of thin-film ionomers, it can be further confirmed that the phase-separation within thin-film ionomers is enhanced after heat treatment that builds more oxygen transport pathways inside the ionomer. This work offers a simple and effective method to enhance the local oxygen transport process and is beneficial for future high performance PEMFC development.
Proton exchange membrane fuel cell (PEMFC) is a promising energy-convert technology. However, the preparation, storage, and transportation of the main fuel, hydrogen, have technical difficulties that hinder the commercialization of fuel cells. Organic liquid at room temperature with high energy density is preferred as the ideal fuel, such as gasoline. Herein, we propose a proof-of-concept PEMFC system that first oxidizes gasoline and generates power at room temperature. In this system, phosphotungstic acid (PTA) serves as the medium energy carrier, obtaining energy from gasoline and releasing it in fuel cells. A peak power density of 5.04 mW cm-2 is reached after optimization. The reaction mechanism is further investigated by using two main compositions of gasoline, toluene, and methyl tertiary-butyl ether (MTBE) to react with PTA. The results further highlight the advantage of PTA in avoiding impurities doping. The newly designed system gives an innovative idea for the use of gasoline.
Spinel oxides of special crystal structure and composition, have been widely applied in biotechnology, laser, sensor technologies, and conversion reaction. In this work, FeCo2O4 powders were prepared by hydrothermal, solid-state, and sol-gel methods to explore the optimal synthesis process of spinel oxides. The effects of annealing temperature on spinel structure were also investigated. In addition, the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) electrocatalytic activities, and practical applications of FeCo2O4 in electrochemical energy conversion devices were explored. Specifically, single-phase FeCo2O4 with smaller particle sizes can be prepared by a procedure including the hydrothermal method and subsequent annealing at 900°C. Moreover, the composite of FeCo2O4 and EC600JD shows splendid OER and ORR activities. And FeCo2O4 spinel oxide reaches a maximum power density of 97.63 mWꞏcm-2 when applied as air cathode of the aluminum-air battery. Our work demonstrates that FeCo2O4 with a simple synthesis process and preeminent electrocatalytic performance is a promising catalyst for metal-air batteries.
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