A relatively inexpensive commercially available RO membrane was shown to be useful for direct seawater H2 generation as the membrane can selectively transport protons and hydroxide ions over other salt ions, and keep the inert anolyte contained to avoid chlorine gas evolution.

The high ionic strength and complex speciation of the anolyte solution within the CuCl(aq)/HCl(aq) electrolytic cell have impeded predictions of the energy requirements for the cell's electrolytic reaction at 25 °C and 1 bar. After collecting experimental open circuit potential (OCP) data and comparing the values obtained with predictions from prospective thermodynamic models, an approach to predict thermodynamic values and the overall efficiency was formulated. The compositions of the experimental measurements ranged from 2-2.5 mol of CuCl(aq) with 8-9 mol of HCl(aq) per kilogram of water in anolyte solution and 8-9 mol of HCl(aq) per kilogram of water in catholyte solution. From the OCP data, it was found that

Saline water represents an inexhaustible source of water for hydrogen production from electrolysis. However, direct saltwater splitting faces challenges due to chlorine evolution at the anode and the development of...

An electrochemical kinetics investigation of the CuCl(aq)/HCl(aq) electrolyzer identified methods to significantly reduce the platinum loadings required to achieve a high cell current density of 0.5 A/cm 2 at 0.7 V. As the CuCl(aq)/HCl(aq) electrolyzer is a key component of the Cu-Cl thermochemical cycle, the economic viability of the Cu-Cl thermochemical cycle was significantly improved by reducing the loading required to achieve 0.5 A/cm 2 . Electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) with a rotating disc electrode were employed to investigate the kinetics of the aqueous Cu II /Cu I chloride complexes reaction on platinum and glassy carbon using a three-electrode cell. It was found that the standard exchange current density of the anodic Cu II /Cu I electrochemical reaction on platinum, 4-12 A/cm 2 , was significantly larger than the values reported for the HER cathodic reaction thus far. In addition, SEM was used to observe the effectiveness of different catalyst application techniques. Through SEM observations, and electrochemical data analysis, the amount of platinum used in a laboratory scale CuCl(aq)/HCl(aq) electrolyzer was reduced from 0.8 mg/cm 2 applied to both electrodes to 0.4 mg/cm 2 on the cathode and zero at the anode while still maintaining a current density of 0.5 A/cm 2 at 0.7 V of applied potential difference. As interest in an energy storage option capable of storing both thermal and electrical energy produced via solar resources increases, low temperature hybrid thermochemical cycles are becoming an attractive candidate to fill this role. In particular, the Cu-Cl hybrid thermochemical cycle's high efficiency and moderate temperature requirements have established itself as a promising option for inexpensive hydrogen generation through harnessing excess thermal and electrical energy from solar resources.1 In addition to utilizing excess energy, the Cu-Cl thermochemical cycle provides a means of efficiently producing hydrogen gas not reliant on fossil fuels.The Cu-Cl hybrid thermochemical cycle uses a number of intermediate compounds, heat, and a small amount of electrical energy, within a series of physical and chemical reactions to split water into hydrogen and oxygen.2-10 One of the most important components in the hybrid cycle is the CuCl(aq)/HCl(aq) electrolytic cell. 11 In the electrolytic step of this cycle, the general electrochemical reaction consists of an anode reaction in which aqueous Cu I chloride complex species are oxidized to aqueous Cu II chloride complex species, and a cathode reaction in which HCl(aq) is reduced to H 2 (aq) with transfer of H + (aq) through a cation conductive membrane. This process is usually simplified as follows:To increase the solubility of CuCl(s) in the anolyte, a high concentration of HCl(aq) is typically used. Similarly, the catholyte comprises of highly concentrated HCl(aq) to avoid copper deposition at the cathode. 9Previous research established an electrolytic cell design that employed membrane electrode assemb...

The hydrogen reaction in concentrated HCl(aq) solutions is a key reaction for the CuCl(aq)/HCl(aq) electrolytic cell. Here, electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) were used to obtain new data for the hydrogen reaction on platinum submerged in highly concentrated acidic solutions at 25 °C and 0.1 MPa. LSV and EIS data were collected for Pt in 0.5 mol/L H 2 SO 4 (aq), 1 mol/L HCl(aq) and 7.71 mol/L HCl(aq) solutions. It was found that exchange current density (j 0 ) values varied between 1 and 2 mA/cm 2 . An equivalent circuit model was used to obtain comparable j 0 and limiting current density values from EIS data relative to values obtained with LSV data. It was found that as the concentration of acid increased, a noticeable decrease in the performance was observed.