The effect of carbon nanotubes on the corrosion and tribological behavior of electroless Ni-P-CNT composite coating

In this study, Ni-P-CNT composite coating was successfully deposited on the surface of copper by electroless plating. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were used to characterize the coatings. The wear behavior of the coatings was investigated using a pin-on-disk test rig and subsequently friction coefficient data were reported. The corrosion behavior of the Ni-P and Ni-P-CNT coated specimen were evaluated through polarization curves and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl aqueous solution at the room temperature. The results indicated that the incorporation of carbon nanotubes (CNTs) in the coating improved both tribological behavior and corrosion resistance. These improvements have been attributed to superior mechanical properties, unique topological structure and high chemical stability of nanotubes.     

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.