Ostwald Ripening Of Particles Research Articles

Surface unsaturated WOx activating PtNi alloy nanowires for oxygen reduction reaction

PtNi alloy nanoparticles display promising catalytic activity for oxygen reduction reaction (ORR), while the Ostwald ripening of particles and the dissolution/migration of surface atoms greatly affect its stability thus restricting the application. Herein, the WOx-surface modified PtNi alloy nanowires (WOx-PtNi NWs) exhibiting enhanced ORR catalytic property is reported, which has high aspect ratio with the diameter of only 2 ∼ 3 nm. It is found that the WOx-PtNi NWs shows a volcano relationship between the ORR activity and the content of WOx. The WOx-(0.25)-PtNi NWs has the best performance among all the synthesized catalysts. Its mass activity (0.85 A mg−1Pt) is reduced by only 23.89% after 30k cycles durability test, which is much more stable than that of PtNi NWs (0.33 A mg−1Pt, 45.94%) and Pt/C (0.14 A mg−1Pt, 57.79%). Hence this work achieves an effective regulation of the ORR activity for PtNi alloy NWs by the synergistic effect of WOx on Pt.

Prediction of the size distribution of precipitates

Modelling has proven to be an efficient way of cutting the time and costs associated with the investigation of materials properties. A new mathematical model for the prediction of the particle size distribution of precipitates has been developed. The model allows the description of all stages of the precipitation process: nucleation, growth and Ostwald ripening of particles. The incorporation of existing thermodynamic databases allows the simulation of a formation of dispersed phases in commercial multicomponent alloys.The influence of the model parameters on the final particle size distribution was investigated with the example of NbC formation in austenite. It was shown that the interfacial energy of a particle‐matrix interface has the most significant effect on the final particle arrangement. A pre‐exponential factor, which is the subject of nucleation theories, plays a less significant role in the final particle arrangement.