Xiaoteng Liu

Study of niobium and tantalum doped titania-supported Pt electrocatalysts for methanol oxidation and oxygen reduction reactions

Niobium and tantalum doped TiO2 nanoparticles were prepared as catalyst substrates by an improved sol–gel method. Catalysts consisting of 20 wt.% Pt supported on these substrates were synthesised and studied for the methanol oxidation reaction (MOR) and the oxygen reduction reaction (ORR). The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Results indicated that the support materials had an average particle size of 26 nm and that the dopants were evenly distributed in the TiO2. The catalysts were also investigated with a range of electrochemical analyses and benchmarked against pure TiO2 nanoparticles and carbon-supported Pt catalysts with the same composition. The samples showed dramatically better stability than the carbon-supported Pt catalysts in an accelerated degradation test (ADT) under various experimental conditions. The MOR activities of these samples were also increased due to the presence of oxide material substrates, which provide active sites at lower potentials. Thus, the Nb and Ta doped TiO2-supported Pt catalysts were found to be promising methanol oxidation catalysts in terms of their catalytic activity and stability.

A polybenzimidazole/graphite oxide based three layer membrane for intermediate temperature polymer electrolyte membrane fuel cells

A three layer membrane (TLM) of polybenzimidazole/graphite oxide/polybenzimidazole (PBI/GO/PBI) has been fabricated as an electrolyte for intermediate temperature polymer exchange membrane fuel cells (IT-PEMFCs). The membrane is prepared by encapsulating a GO layer with two single PBI membranes via a layer-by-layer procedure and subsequently imbibed with phosphoric acid (PA). The TLM exhibits a lower swelling ratio than that of the pristine PBI membrane at the same PA loading time. The mechanical strength of the TLM could reach 28.6 MPa at 150 °C, significantly higher than that of a PBI membrane (12.2 MPa). The TLM is loaded with a PA amount of 2.23H3PO4 molecules per repeat unit (PRU), which provides a proton conductivity of 0.0138 S cm−1 at 150 °C. The three layer structure promotes a membrane for PEMFCs with lower PA leakage and material corrosion. The fuel cell performance based on TLM exhibits a peak power density of 210 mW cm−2 at 150 °C.

Determining the Effect of Plasma Pre‐Treatment on Antimony Tin Oxide to Support Pt@Pd and the Oxygen Reduction Reaction Activity

This article reveals the effect of plasma pre‐treatment on antimony tin oxide (ATO) nanoparticles. The effect is to allow Pt@Pd to be deposited homogeneously on the ATO surface with high dispersion and narrow particle size distribution. The Pt@Pd core–shell catalyst was prepared using the polyol method and shows a dramatic improvement towards ORR activity and durability.

Al2O3 Disk Supported Si3N4 Hydrogen Purification Membrane for Low Temperature Polymer Electrolyte Membrane Fuel Cells

Reformate gas, a commonly employed fuel for polymer electrolyte membrane fuel cells (PEMFCs), contains carbon monoxide, which poisons Pt-containing anodes in such devices. A novel, low-cost mesoporous Si3N4 selective gas separation material was tested as a hydrogen clean-up membrane to remove CO from simulated feed gas to single-cell PEMFC, employing Nafion as the polymer electrolyte membrane. Polarization and power density measurements and gas chromatography showed a clear effect of separating the CO from the gas mixture; the performance and durability of the fuel cell was thereby significantly improved.