Currently, according to conventional charge-discharge profiles, energy consumed in charging Capacitive Deionization (CDI) systems is always a function of different parameters (current used for charging, capacitance and current employed for discharging) making it difficult to separate the effect of these parameters on CDI performance and energy efficiency. Thus, energy efficiencies are strongly influenced by the current in the preceding charge or discharge stage of the process. We find consistently that this phenomenon, which to our knowledge has not been addressed in previous CDI communications, is much more intense when different currents are applied for each of the charging and discharging cycles. The investigation reported here provides a mechanistic analysis of the operational aspects of CDI and develops a new procedure that allows for a precise evaluation of performance and energy efficiency. Furthermore, the model developed here allows one to separate charge and discharge cycles, and therefore contributes to the possibility of defining an operational mode for real-world devices in which effective separation of deionization and regeneration steps needs to be implemented. This method of analysis could be useful not only for CDI but also for other electrochemical systems such as in secondary batteries and supercapacitors where charge and discharge are typically employed.
Ternary chalcogenides (AB 2 X 4 ) based on the spinel structure are gaining a great deal of attention because of the possibility of tuning their magnetic and optoelectronic properties not only by changing chemical composition but also by altering their degree of inversion. Here we report a rapid highpressure synthetic method for the synthesis of MIn 2 S 4 powders starting from commercially available solid sulfides. We prove the versatility of our method by reporting the synthesis of six members of the MIn 2 S 4 family (M = Mn, Fe, Co, Ni, Zn, and [a] 1558 Cd) under high-pressure conditions (3.5 GPa); these compounds show complete to moderate degrees of inversion. Furthermore, this family covers a spectral region that includes visible band gaps. Interestingly, the structural refinement carried out by Xray and neutron diffraction allows one to establish positive correlations between the gap and different parameters, including the degree of inversion. Finally, as a proof-of-concept, these ternary chalcogenides show moderate photocatalytic hydrogen production from aqueous solutions. and semiconducting properties, [2,3] whereas others show photoluminescence [4] and have found applications as photoconverters. [5] Eur. J. Inorg. Chem. 2016, 1558-1565 www.eurjic.org
Se-modified g-C 3 N 4 was synthesized from sonicated aqueous suspensions of melamine cyanurate and SeO 2 . The different thermal condensation temperatures in the 500-650 ºC range were found to influence the photophysical properties and hydrogen evolution rates. H 2 evolution increased dramatically by two orders of magnitude when Pt co-catalyst (1 wt.%) was incorporated, reaching an HER of 75 µmol H 2 /h.
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