Xiaoping Qin

Preparation and characterization of Ti0.7Sn0.3O2 as catalyst support for oxygen reduction reaction

Abstract Sn-doped TiO2 nanoparticles with high surface area of 125.7 m2·g−1 are synthesized via a simple one-step hydrothermal method and explored as the cathode catalyst support for proton exchange membrane fuel cells. The synthesized support materials are studied by X-ray diffraction analysis, energy dispersive X-ray spectroscopy and transmission electron microscopy. It is found that the conductivity has been greatly improved by the addition of 30 mol% Sn and Pt nanoparticles are well dispersed on Ti0.7Sn0.3O2 support with an average size of 2.44 nm. Electrochemical studies show that the Ti0.7Sn0.3O2 nanoparticles have excellent electrochemical stability under a high potential compared to Vulcan XC-72. The as-synthesized Pt/Ti0.7Sn0.3O2 exhibits high and stable electrocatalytic activity for the oxygen reduction reaction. The Pt/Ti0.7Sn0.3O2 catalyst reserves most of its electrochemically active surface area (ECA), and its half wave potential difference is 11 mV, which is lower than that of Pt/XC-72 (36 mV) under 10 h potential hold at 1.4 V vs. NHE. In addition, the ECA degradation of Pt/Ti0.7Sn0.3O2 is 1.9 times lower than commercial Pt/XC-72 under 500 potential cycles between 0.6 V and 1.2 V vs. NHE. Therefore, the as synthesized Pt/Ti0.7Sn0.3O2 can be considered as a promising alternative cathode catalyst for proton exchange membrane fuel cells.

Fabrication of a highly dispersed Pd core @Pt shell electrocatalyst for the oxygen reduction reaction

ABSTRACT Core-shell nanostructures have been widely investigated to improve the electrocatalytic performance of platinum. However, organic precursors, surfactants or high temperature are usually necessary during the preparation procedure. Unfortunately, these requirements limit the application of these methods on a large scale. Herein, a Pd core @Pt shell nanostructure was fabricated through the reduction of K 2 PtCl 4 by dissociated hydrogen at room temperature without the assistance of either a surfactant or a high-boiling point solvent. The shell thickness of this nanostructure was successfully controlled by varying the amount of K 2 PtCl 4 ; core-shell nanoparticles with a shell thickness of 0.45, 0.75 and 0.90 nm were obtained, as determined by TEM. The remarkable crystallinity and epitaxial growth of the Pd core @Pt shell nanostructure were revealed by HRTEM and EDS. According to ICP and XPS, surface segregation of Pt was established. The impressive ORR performance was attributed to the weak adsorption strength of the OH ads species, which resulted from the electron transfer impact between the Pd core and Pt shell . The facile and clean preparation method can be used to prepare other core-shell nanostructures under a mild atmosphere.

ArticleFabrication of a highly dispersed Pdcore@Ptshell electrocatalyst for the oxygen reduction reaction

ABSTRACT Core-shell nanostructures have been widely investigated to improve the electrocatalytic performance of platinum. However, organic precursors, surfactants or high temperature are usually necessary during the preparation procedure. Unfortunately, these requirements limit the application of these methods on a large scale. Herein, a Pd core @Pt shell nanostructure was fabricated through the reduction of K 2 PtCl 4 by dissociated hydrogen at room temperature without the assistance of either a surfactant or a high-boiling point solvent. The shell thickness of this nanostructure was successfully controlled by varying the amount of K 2 PtCl 4 ; core-shell nanoparticles with a shell thickness of 0.45, 0.75 and 0.90 nm were obtained, as determined by TEM. The remarkable crystallinity and epitaxial growth of the Pd core @Pt shell nanostructure were revealed by HRTEM and EDS. According to ICP and XPS, surface segregation of Pt was established. The impressive ORR performance was attributed to the weak adsorption strength of the OH ads species, which resulted from the electron transfer impact between the Pd core and Pt shell . The facile and clean preparation method can be used to prepare other core-shell nanostructures under a mild atmosphere.