Research progress of silicon nanostructures prepared by electrochemical etching based on galvanic cells

Metal-assisted etching of silicon in HF aqueous solution has attracted widespread attention due to its potential applications in electronics, photonics, renewable energy, and biotechnology. In this paper, the basic process and mechanism of metal assisted electrochemical etching of silicon in vapor or liquid atmosphere based on galvanic cells are reviewed. This paper focuses on the use of gas-phase oxidants O2 and H2O2 instead of liquid phase oxidants Fe(NO3)3 and H2O2 to catalyze the etching of silicon in the vapor atmosphere of HF aqueous solution. The mechanism of substrate enhanced metal-assisted chemical etching for the preparation of large-area silicon micro nanostructure arrays is summarized, and the impact of substrate type and surface area on reactive etching is discussed.

Electromagnetic Field as Agent Moving Bioactive Cations. A New Antimicrobial System in Architecture Technology

There is a new described antifungal system (GALVI) involving the moving of bioactive ions of Zn, Cu and Bi for the protection of cultural heritage objects such as buildings, sculptures and stretchers. There were two kinds of galvanic cells that were used: the first composed of a two-electrodes system, Zn, Cu, and second one composed of a three-electrodes system, Zn, Bi and Cu. Moreover, two-phase media are proposed with various kinds of rocks used in architectonical objects. Microorganisms inhabit the boundaries of two liquid and solid phases. This enables the investigation of the process of rock colonization. Possible applications of the suggested GALVI system are mentioned.

Preparation and characterization of nano-galvanic bimetallic Fe/Sn nanoparticles deposited on talc and its enhanced performance in Cr(VI) removal

In this study, talc-supported nano-galvanic Sn doped nZVI (Talc-nZVI/Sn) bimetallic particles were successfully synthesized and utilized for Cr(VI) remediation. Talc-nZVI/Sn nanoparticles were characterized by FESEM, EDS, FTIR, XRD, zeta potential, and BET analysis. The findings verified the uniform dispersion of nZVI/Sn spherical nanoparticles on talc surface with a size of 30–200 nm, and highest specific surface area of 146.38 m2/g. The formation of numerous nano-galvanic cells between nZVI core and Sn shell enhanced the potential of bimetallic particles in Cr(VI) mitigation. Moreover, batch experiments were carried out to investigate optimum conditions for Cr(VI) elimination and total Cr(VI) removal was achieved in 20 min using Sn/Fe mass ratio of 6/1, the adsorbent dosage of 2 g/L, initial Cr(VI) concentration of 80 mg/L, at the acidic environment (pH = 5) and temperature of 303 K. Besides, co-existing of metallic cations turned out to facilitate the electron transfer from the nano-galvanic couple of NZVI/Sn, and suggested the revolution of bimetallic particles to trimetallic composites. The aging study of the nanocomposite confirmed its constant high activity during 60 days. The removal reaction was well described by the pseudo-second-order kinetic and the modified Langmuir isotherm models. Overall, due to the synergistic galvanic cell effect of nZVI/Sn nanoparticles and full coverage of active sites by Sn layer, Talc-nZVI/6Sn was utilized as a promising nanocomposite for fast and highly efficient Cr(VI) elimination.

Preparation and Characterization of Nano-galvanic Bimetallic Fe/Sn Nanoparticles Deposited on Talc and its Enhanced Performance in Cr(VI) Removal

In this study, talc-supported nano-galvanic nZVI/Sn bimetallic particles was successfully synthesized and utilized for Cr(VI) remediation. Talc-nZVI/Sn nanoparticles were characterized by SEM, EDS, FTIR, XRD, zeta potential, and BET analysis. The findings verified the uniform dispersion of nZVI/Sn nanoparticles on talc surface. The formation of numerous nano-galvanic cells between nZVI core and Sn shell enhanced the potential of bimetallic particles in Cr(VI) mitigation. Batch experiments were carried out to investigate optimum conditions and total Cr(VI) removal was achieved in 20 minutes using Sn/Fe mass ratio of 6/1, the adsorbent dosage of 2 g/L, initial Cr(VI) concentration of 80 mg/L, at the acidic environment (pH=5) and temperature of 303 K. Besides, co-existing of metallic cations turned out to facilitate the electron transfer from the nano-galvanic couple of NZVI/Sn and suggested the revolution of bimetallic particles to trimetallic composites. The aging study of the nanocomposite confirmed its constant high activity during 60 days. The removal reaction was well described by the pseudo-second-order kinetic and the Langmuir isotherm models. Overall, due to the synergistic galvanic cell effect of nZVI/Sn nanoparticles and full coverage of active sites by Sn layer, Talc-nZVI/6Sn was utilized as a promising nanocomposite for fast and highly efficient Cr(VI) elimination.

Novel Quantum Gravity Model of the Physics of Operability of Galvanic Cells and Electrical Power Generation

The dimensions of the physical variables like resistance, electrical current and potential difference associated with ohm’s law have been evaluated applying the theory of quantum gravity (QG theory) and those dimensions have been utilized to evaluate the actual mechanism of functioning of the galvanic cells to originate electricity, power and power transmissions. Itself, the terminology, ‘Electromotive Force (emf) ‘of a galvanic cell does not stand at the proper stead, as has been established in this article by revealing the unidimensional characteristics of emf or the difference in electrode potential between the positive electrode (cathode) and the negative electrode (anode). In QG theory, Force is a 2-dimensional physical variable of the universe, being originated from unidimensional ‘Distance’ or ‘Entropy’. The traditional concept of the mapping the emf of galvanic cells by the free energy changes of the chemical reaction occurring in a cell is not justified and the energy output from a galvanic cell has been proved to be a phenomenon of continuous passage or flow of in-situ activation volumes or activation energies of the chemical reactions occurring, through the external conducting paths.