Improving the Stability and Ethanol Electro‐Oxidation Activity of Pt Catalysts by Selectively Anchoring Pt Particles on Carbon‐Nanotubes‐Supported‐SnO2

To improve the stability and activity of Pt catalysts for ethanol electro‐oxidation, Pt nanoparticles were selectively deposited on carbon‐nanotubes (CNTs)‐supported‐SnO₂ to prepare Pt/SnO₂/CNTs and Pt/CNTs was prepared by impregnation method for reference study. X‐ray diffraction (XRD) was used to confirm the crystalline structures of Pt/SnO₂/CNTs and Pt/CNTs. The stabilities of Pt/SnO₂/CNTs and Pt/CNTs were compared by analyzing the Pt size increase amplitude using transmission electron microscopy (TEM) images recorded before and after cyclic voltammetry (CV) sweeping. The results showed that the Pt size increase amplitude is evidently smaller for Pt/SnO₂/CNTs, indicating the higher stability of Pt/SnO₂/CNTs. Although both catalysts exhibit degradation of electrochemical active surface area (EAS) after CV sweeping, the EAS degradation for the former is lower, further confirming the higher stability of Pt/SnO₂/CNTs. CV and potentiostatic current–time curves were recorded for ethanol electro‐oxidation on both catalysts before and after CV sweeping and the results showed that the mass specific activity of Pt/CNTs increases more than that of Pt/SnO₂/CNTs, indicating that Pt/CNTs experiences more severe evolution and is less stable. The calculated area specific activity of Pt/SnO₂/CNTs is larger than that of Pt/CNTs, indicating SnO₂ can co‐catalyze Pt due to plenty of interfaces between SnO₂ and Pt.     

An Algorithm for On‐line Measurement of the Internal Resistance of Proton Exchange Membrane Fuel Cell

The internal resistance of proton exchange membrane fuel cell (PEMFC) system is difficult to measure on‐line due to its variation with time. The traditional electrochemical impedance spectroscopy (EIS) and its variants such as high frequency resistance (HFR) can be used to measure the resistance when the system is in steady state, but they fail in automotive applications where a change in speed or inclination modifications could lead to a sharp fluctuation in demand on power. In order to resolve this problem, a novel algorithm is proposed in this paper to estimate the resistance based on the alternating current (AC) impedance spectroscopy technique by adding an extra term to eliminate the errors caused by voltage variation or when the system is under unsteady state. Numerical simulations show that the proposed algorithm can not only accurately track the variation of the internal resistance, but is also robust against the noises caused by uncertainty and measurements.