Zero-charge point

Points of Zero Charge. Points of zero charge (pzc) are pH-values where the net surface charge is zero. We consider here above all the surface conditions where the... 

Figure 3. XPS spectra of a silicon sample containing ca. 30 nm thick oxide. A strip of gold metal is tied for referencing under different voltage stress. The inset displays the measured binding energy difference between the Si2p of the oxide layer (Si4+), and the Au4f of the gold metal. Zero Charge Point (ZCP) is obtained at ca. +1V stress.

Potential of zero charge -+ point of zero charge... 

Note that the farther away the electric potential of the carbon surface is from the potential of zero charge point ( pzc) l e higher the disjoining pressure is. In principle, this may result in a systematic variation of the support pore size in Me/C catalysts with potential (similar to the electrocapillary curve [96,97]) and consequently the efficiency of metal particle blocking by the pore walls. Such behavior of porous carbons obviously can influence the measurements of the electrochemically active surface area and might be one of the reasons for the observed correlation between the apparent dispersion of Pt/C catalysts, measured by cyclic voltammetry, and pHpzc of the supports [95], whereas no noticeable difference in the particle size has been observed with HRTEM. Undoubtedly, this problem needs further investigation. 

All available sources were used to obtain the data in this reference making it the definitive resource on PZC/IEP. Destined to become a classic. Surface Charging and Points of Zero Charge points the way for further research with tried and true methods that help researchers avoid the doubt that can lead to countless hours of unnecessary research. 

Isoelectric point is a pH value, at which electrokinetic potential C on the slip plane is equal to 0, at the participation in ion exchange only of protons H% i.e., in distilled and deionized water. In Western literature it is denoted pi or lEP. Isoelectric point of a mineral is determined by the electrokinetic method, i.e., from the pH value, at which a suspension of its particles has the lowest mobility in the electric field. Isoelectric point. As opposed to the zero charge point, isoelectric point characterizes zero charge of hydrodynamic interface, i.e., conditions when 0. 

After the zero-charge point the adsorption of chloroform is maximal, and within the range of potentials from —0.6 to —1.6 V is constant,... 

Theoretical concepts of specific (per unit true electrode surface area) EDL capacitance are based on the known classical theories of EDL developed by Helmholtz, Stern, Gouy-Chapman, Grahame, and so on. One of the directions of modem smdies of EDL is elucidation of ratios between different surface layer characteristics. These include specific capacitances in zero charge points, electronic work functions of metals, their liophilicity, zero charge potentials. Correlations are established between many of these characteristics in a number of metals and solvents. At the same time, there are significant deviations from main trends. Zero charge points were first determined for different carbon materials in the works of Frumkin et al. 

The changes of flotation performance of amino acid in the vicinity of the zero charge point had been discussed. The flotation results of white mica, hematite, and quartz using sodium A-alkyl-y -aminopropanoate are found in Fig. 3.3 (Volume 1). 

The influence of pH on the solubility of amino acid is shown in Fig. 2.3. As shown in Fig. 2.3, the solubility of amino acid appears to be smallest when the solution pH approaches the zero charge point. 

Table 5.5. Zero charge point (ZCP) of unoxIdized and oxidized activated carbon...

In this limit, Ob depends only upon the insulator characteristics, because the Fermi level is pinned at the zero-charge point Ezcf- This is similar to Bardeen s result, although the nature of the states which pin the Fermi... 

At a metal-oxide contact, there also exists an interfacial dipole, when the metal Fermi level does not coincide with the oxide zero-charge point. The electron-electron interaction term may be estimated using the analytical self-consistent approach presented in the previous section ... 

According to the data of Grigoriev and Damaskin [29], it is possible to calculate the kgi values for amyl alcohol using Eq. (24) (Table 2). From these data [29] it was calculated that with sodium fluoride as supporting electrolyte y = 7.2 V", and the displacement of the zero-charge point relative to the maximum adsorption point... 

---