Electrochemistry of Gallium

Abstract

:Gallium is an important element in the production of a variety of compound semiconductors for optoelectronic devices. Gallium has a low melting point and is easily oxidized to give oxides of different compositions that depend on the conditions of solutions containing Ga. Gallium electrode reaction is highly irreversible in acidic media at the dropping mercury electrode. The passive film on a gallium surface is formed during anodic oxidation of gallium metal in alkaline media. Besides, some results in published reports have not been consistent and reproducible. An increase in the demand of intermetallic compounds and semiconductors containing gallium gives rise to studies on electrosynthesis of them and an increase of gallium concentration in the environment with various application of gallium causes the development of electroanalysis tools of Ga. It is required to understand the electrochemistry of Ga and to predict the electrochemical behavior of Ga to meet these needs. Any review papers related to the electrochemistry of gallium have not been published since 1978, when the review on the subject was published by Popova et al. In this study, the redox behavior, anodic oxidation, and electrodeposition of gallium, and trace determination of gallium by stripping voltammetries will be reviewed.

Discovery of a Voltage-Stimulated Heartbeat Effect in Droplets of Liquid Gallium

“…The efficient alkaline electrolyte appears to act as "adrenaline" to speed up the reaction compared to the acidic solutions. The fact that beating occurs in both acidic and alkaline solutions confirms the well-established fact that the Ga 2 O 3 forms in a wide variety of liquid solutions and pH levels [37]. Gravity also has a strong effect on the frequency, as a small incline is essential to generate reproducible beating [see Fig.…”

“…The voltage enables electrolysis and reactions to proceed at the surface of the gallium. Above a threshold voltage, anodic surface oxidation of liquid gallium into Ga 2 O 3 becomes possible via the nonspontaneous reaction [3,37],…”

“…The drop continues to move away from the electrode under the influence of linear momentum and gravity, until it approaches the center (Δt ¼ 198 ms). Throughout its free trajectory, the apparent diameter begins to shrink, since without the applied voltage, hydroxyl ions can quickly etch the oxide layer surrounding the liquid metal surface [37] leading to the recovery of a state with high surface tension [19,38]. Consequently, in the final phase (from Δt ¼ 264 ms), the droplet returns to a spherical shape, and under the influence of gravity, ultimately drifts downhill back to the inner wall of the electrode to begin the next cycle.…”

“…This involves a process whereby any residual charge is redistributed at the surface, producing a dipole that balances the external potential. In the electrolyte, this involves forming the electrical-double layer on the liquid metal, structured with negative hydroxyl groups terminating the metal oxide counterbalanced by external positive ions [37], providing a capacitance that leads to a long-lived charge on the drop for several seconds [19].…”

Extraction of Ga(III) by Di‐(2‐ethylhexyl)phosphoric acid (D2EHPA)‐Modified XAD‐4 Resins Prepared by Solvent‐Nonsolvent Modification

“…Calculation based on MINEQL+ software, depending on the pH value, demonstrates that various trivalent gallium ions such as Ga 3+ , Ga(OH) 2+ , GaO + , GaO 2-, H 2 GaO 3-, Ga(OH) 4-, HGaO 3 2-, GaO 3 3-, and Ga 2 O 3 may exist in aqueous solutions [25,26]. At higher pH, the negatively charged Ga(III) species dominate.…”