Shape‐controlled catalysis : High‐quality Pt–Cu nanocubes with an average size of about 8 nm (see picture, scale bar=20 nm) were synthesized from a high‐temperature organic solution system in the presence of various capping ligands. These cubic Pt–Cu nanocrystals terminated with {100} facets demonstrated a superior catalytic activity towards methanol oxidation compared to similar sized Pt–Cu and Pt nanospheres.
Carbon supported Pt(Pt/C) electrocatalysts were prepared with glucose as protection agent and NaBH4 as reductant. The Pt nanoparticles deposited on carbon support presented reduced size and well dispersity attributed to the protection effect of glucose. Glucose absorbed on the particle surface was readily removed by water washing without leading to agglomeration of the Pt nanoparticles. The as-prepared Pt/C electrocatalysts showed improved mass activity for methanol electrooxidation compared to the catalyst prepared without glucose protection. The improved performance is attributed to the larger electrochemical active surface area thus increased active sites on the Pt/C elctrocatalysts prepared under the protection of glucose. 相似文献
The mixed oxide phosphate (≡SiO)2Ti(O3POH)2 having a specific surface area of SBET= 595 m2 g−1 and an average pore volume of 0.43 mL g−1 was prepared by the sol-gel processing method. The material showed the following characteristics: Ti=11.6 wt% and P=10.5 wt%;
ion exchange capacity of 0.60 mmol g−1. Meldola's Blue (MLB) dye was adsorbed, by an ion exchange reaction, from an aqueous solution in a quantity of 0.62 mmol
g−1. The dye was strongly retained and was not easily leached from the matrix even in presence of 0.5 M electrolyte solution.
Changing the solution pH between 2.5 and 7.0, the midpoint potential of the dye-adsorbed (≡SiO)2 Ti(O3POMLB)2 matrix carbon paste electrode remained practically constant, i.e. about 20 mV vs. SCE. This is not the usual behaviour of
MLB since its midpoint potential changes considerably in solution phase as the pH is changed. The modified electrode has proved
to be stable and electrocatalytically active for hydrazine oxidation at pH 6.
Received: 22 June 1999 / Accepted: 7 September 1999 相似文献
