1,721,061 research outputs found
Fostering students’ willingness and interest in argumentative writing: an intervention study.
No full textControlled synthesis of Pt3Sn/C electrocatalysts with exclusive Sn-Pt interaction designed for use in direct methanol fuel cells
No full textAlloy-type Sn-Pt/C electrocatalysts with Pt/Sn= 1.8-3.0 ratios and exclusive Sn-Pt interaction have
been prepared by means of Controlled Surface Reactions (CSRs). As demonstrated by XRD the incorporation of
Sn onto Pt/C was achieved satisfactorily yielding a near-stoichiometric fcc Pt3Sn alloy phase along with a certain
amount of the Pt(1-x)Snx solid solution. The content and dispersion of the fcc Pt3Sn phase within the
electrocatalysts can be controlled by tuning the reaction conditions of CSRs. No evidence of the presence of
SnO2 phases in the Sn-modified Pt/C samples were found by means of the XRD and EDS analysis. According to
in situ XPS studies the pre-treatment in hydrogen at 350°C resulted in complete reduction of tin to Sn0. These
results demonstrate that the method of CSRs is a powerful tool to create of Pt-Sn bimetallic nanoparticles
exclusively, without tin introduction onto the carbon support. The performance of the intermetallic SnPt/C
catalysts in the CO and methanol electrooxidation reactions depends on the actual composition of the exposed
surface and the size of bimetallic particles. In the consecutive tin introduction the decrease of the amount of
SnEt4 precursor added per period, accompanied with an increase of the number of anchoring periods, resulted in
an increase of the activity in both electrooxidation reactions as a consequence of an optimal balance of Pt/Sn
ratio, the content of fcc Pt3Sn phase and metal particle size. It was demonstrated that the increasing tin content
above a certain (optimal) amount gives rise to a negative effect on the catalyst performance in the CO and
methanol electrooxidation
Phase Composition, Microstructure and Sintering in the System Co-Li2CO3
No full textCo and Li2CO3 were used as starting materials to obtain cobalt based plaques of potential use in molten carbonate fuel cells
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
