Szklarczyk

P. Zelenay and A. Wieckowski, in Electrochemical Interfaces, Modern Techniques for in situ Interface Characterization, Ed. by H. D. Abruna, VCH Publishers, New York, 1991. A. Wieckowski, M. Szklarczyk, and 1. Sobkowski, I. Electroanal. Chem. 113 (1980) 79. A. Wieckowski, 1. Sobkowski, P. Zelenay, and K. Eranaszczuk, Electrochim. Acta 26... 

PZelenay,M.Szklarczyk,M. Winnicka-Maurin,andJ.Sobkowski, J.Electroanal. Chem. 308 (1991) 269. 

Szklarczyk M, Bockris JOM (1984) Photoelectrochemical evolution of hydrogen on p-indium phosphide. J Phys Chem 88 5241-5245... 

Fig. 6.96. Deformation of the adsorbed ion due to the electric field at the metal-solution interphase. (Reprinted from J. O M. Bockris, M. Gamboa-Aldeco, and M. Szklarczyk, J. Electroanal. Chem. 339 355, copyright 1992, Fig. 16, with permission from Elsevier Science.)...

The sensitivity of images of metal surfaces obtained through the solution is less than that in air. Crystal steps on a 1-nm scale can be discerned and in a few cases (e.g., Pb on C Szklarczyk and Bockris, 1989) individual atoms can be distinguished and the interatomic distance measured. An STM picture is shown in Fig. 7.65. 

M. Szklarczyk and J. O M. Bockris, J. Electrochem. Soc. 137 452 (1990). First STM report ofdistinguishability of atoms on surface in contact with liquid. 

What of the future of mechanism determination Is it not likely that as the decades proceed, the indirect reasoning we now use (interpreting this trend or that to favor one mechanism and to be more likely than the interpretation offered by mechanisms Y, Z, etc.), will fade away, their introductory work done Thus, in 1989 (Szklarczyk, Velev,... 

Fig. 10.14. Potentiodynamic runs of p-Si electrode in 0.5 M H2S04. Illumination by a 50-mW cm-2 Xe lamp. The etching procedures were in HF and HNOg, and from H to L the degree of HF etching increased. (Reprinted from M. Szklarczyk, J. O M. Bockris, V. Brusic, and G. Sparrow, Int. J. Hydrogen Energy, 9 707, Copyright 1984. Reproduced with permission of T.Nejat Veziroglu.)...

A somewhat different use of scanning tunneling microscopy to measure surface states has been made by Szklarczyk and Gonzalez-Martin (1991) and by Uosaki (1995) (see Figs. 10.16 and 10.17). 

The first step was the evolution away from the Schottky barrier model of photoelectrochemistry caused by the evidence from the late 1970s onward that the rate of photoelectrochemical reactions was heavily dependent on surface effects (Uosaki, 1981 Szklarczyk, 1983). This was followed by the use of both a photocathode and a photoanode in the same cell (Ohashi, 1977). Then the use of nonactive thin protective passive layers of oxides and sulfides allowed photoanodes to operate in potential regions in which they would otherwise have dissolved (Bockris and Uosaki, 1977). The final step was the introduction of electrocatalysis of both hydrogen and oxygen evolution by means of metal islets of appropriate catalytic power (Bockris and Szklarczyk, 1983). 

Fig. 10.31. Image of p-Si in air Vbias = +1.0 V (Reprinted from M. Szklarczyk, A. Gonzalez-Martin, O. Velev, and J. O M. Bockris, STM Studies of p-Si(111) substrate in Air and in Electrolytic Environment, Surf. Sci. 237, Copyright 1990, Fig. 7, with permission from Elsevier Science.)...

The resolution obtained with the laser spot technique is far exceeded by scanning tunneling microscopy where, in some cases, atomic resolution in electrochemical cases has been reached (Szklarczyk and Velev, 1989). The first successful studies of semiconductors in air (Fig. 10.31) and in an electrochemical situation (Fig. 10.32) were made onp-Si 111 (Gonzalez-Martin, 1990). It was found that the electrochemical formation of SiOx and SiOH induces surface states at 0.25 V above the valence band at the surface (Fig. 10.33). 

The reversible potential ofBr2 + 2e —> 2 Br is 1.08 V atm. The pH of sea water is near 7 and 25 °C hence the reversible potential of 2H+ + 2e —> Hj is about -0.42 V. The reversible cell potential would be then about 1.5 V. The idea here is to reduce the potential below the thermodynamically reversible value by photoillumination ofthe anode (photoassisted water decomposition Szklarczyk, 1983). 

---