Effect of ion and negative ion temperatures on KdV and mKdV solitons in a multicomponent plasma

The formation of ion-acoustic solitons (IASs) in an unmagnetized plasma with negative ions has been investigated through the KdV equation in both the situations \(Q^{\prime}\left( { = m_{j} /m_{i} = {\text{negative}}\;{\text{to}}\;{\text{positive}}\;{\text{ion}}\;{\text{mass}}\;{\text{ratio}}} \right)\) less and greater than one and the mKdV equation only for \(Q^{\prime} > 1\). The existence of both KdV and mKdV solitons has been established for \(\alpha \left( { = {\text{ion}}\;{\text{to}}\;{\text{electron}}\;{\text{temperature}}\;{\text{ratio}}} \right)\; > \;\beta \left( { = {\text{negative}}\;{\text{ion}}\;{\text{to}}\;{\text{electron}}\;{\text{temperature}}\;{\text{ratio}}} \right)\) and \(\alpha < \beta\), which is the new outcome of the current investigation. Furthermore, the existence of both compressive and rarefactive solitons for \(Q^{\prime} > 1\) and \(Q^{\prime} < 1\) has been demonstrated.

     

Linking Composition,Structure and Thickness of CoOOH layers to Oxygen Evolution Reaction Activity by Correlative Microscopy

The role of β-CoOOH crystallographic orientations in catalytic activity for the oxygen evolution reaction (OER) remains elusive. We combine correlative electron backscatter diffraction/scanning electrochemical cell microscopy with X-ray photoelectron spectroscopy, transmission electron microscopy, and atom probe tomography to establish the structure–activity relationships of various faceted β-CoOOH formed on a Co microelectrode under OER conditions. We reveal that ≈6 nm β-CoOOH(01 0), grown on [ 0]-oriented Co, exhibits higher OER activity than ≈3 nm β-CoOOH(10 3) or ≈6 nm β-CoOOH(0006) formed on [02 - and [0001]-oriented Co, respectively. This arises from higher amounts of incorporated hydroxyl ions and more easily reducible Co^III−O sites present in β-CoOOH(01 0) than those in the latter two oxyhydroxide facets. Our correlative multimodal approach shows great promise in linking local activity with atomic-scale details of structure, thickness and composition of active species, which opens opportunities to design pre-catalysts with preferred defects that promote the formation of the most active OER species.