The current race for space exploration has hastened the development of electrochemical technologies for the in-situ utilisation of planetary resources for the synthesis of vital chemicals such as O2 and fuels. Understanding the physicochemical properties, such as the density and kinematic viscosity, of aqueous solutions is essential for the design of electrochemical devices for the electrolysis of water and CO2, particularly at low temperatures. The density and kinematic viscosity of highly concentrated Mg(ClO4)2 and KOH solutions have been determined, both at low temperatures and in the presence of CO2 gas. It was found that, for all of the solutions, independent of the concentration or nature of the electrolyte, as the temperature was decreased to 255 K, the density and the viscosity of the solutions increased. Upon saturation with CO2, no significant change to the density and viscosity of Mg(ClO4)2, at all of the temperatures measured, was observed. Conversely, the CO2 saturated solutions of KOH showed significant changes in density and viscosity at all temperatures, likely due to the formation of carbonates. The effects of these changes on the diffusion coefficient for dissolved CO2 is also discussed.

So far electrocatalytic process in aqueous solution have been extensively studied as a function of the temperature in the range 0 and 99 °C but very little is known about electrocatalytic processes at temperatures below the freezing point. In electrochemistry at low temperatures, the reactions associated with water splitting might be suppressed due to the formation of ice-like structure at the interface, while the stabilization of other reaction species can be stabilized resulting in changes to the kinetics of the reactions studied.1-3 In addition, decreasing the temperature of water to subfreezing temperatures would significantly increase the solubility of some gases in water thus affecting the reaction rate and reaction mechanism of the electrochemical reactions. By taking advantage of the high solubility of the carbon monoxide and methane at low temperature, achievable in brines, we report the electrochemical conversion of these gases in aqueous media down to −40 °C. We will report the electrochemical conversion of CO2 at low temperatures and demonstrate, unexpectedly, that its reduction in these conditions follows an anti-Arrhenius kinetics electrochemical environment. We will also show that electrochemical oxidation of CH4 is feasible at subzero temperatures due to the 5-fold increase in the concentration of CH4 and the formation of in gas hydrate slurries. These findings open windows of investigation into electrocatalysis in brines below the freezing point of water.Gas hydrates or clathrates are a crystalline solid formed of water and gas. Clathrates looks and acts much like ice, but it contains large amounts of gas trapped within a crystal structure of water. Gas hydrates such as hydrates of hydrocarbons, sulfur dioxide (SO2) and carbon dioxide (CO2) have been reported but they are only used for academic purposes with just a very few examples which have reached technical application. However, gas hydrates might have play an important role in the origin of life, and the chemistry on gas hydrates is relevant in energy applications in particular for space exploration.We will show the electrochemical behavior of hydrogen and oxygen adsorption and desorption processes on different metal electrodes in aqueous brines at subfreezing temperatures. Finally, we will report the first electrochemical results of the CO2RR and the oxidation of CH4 in aqueous brines at subfreezing temperatures down to -40°C.4 Our results will be explained on the basis of the presence of ice-structure clathrates,5,6 solubility of the gases as a function of temperature, kinematic viscosity, mass transport and the changes in the pH of the solution.7,8 The understanding of the electrochemistry of gas hydrates at low temperature is paramount for the development of sustainable energy cycle based on CH4 and CO2 reversible fuel cells under severe environmental conditions. This will be critical to ensure the availability of key in situ resources sustaining future human exploration and colonization of other planets. References: [1] U. Frese, et a...