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Ionic liquids (ILs) and deep eutectic solvents (DESs) have tremendous potential for reactive capture and conversion (RCC) of CO2 due to their wide electrochemical stability window, low volatility, and high CO2 solubility. There is environmental and economic interest in the direct utilization of the captured CO2 using electrified and modular processes that forgo the thermal- or pressure-swing regeneration steps to concentrate CO2, eliminating the need to compress, transport, or store the gas. The conventional electrochemical conversion of CO2 with aqueous electrolytes presents limited CO2 solubility and high energy requirement to achieve industrially relevant products. Additionally, aqueous systems have competitive hydrogen evolution. In the past decade, there has been significant progress toward the design of ILs and DESs, and their composites to separate CO2 from dilute streams. In parallel, but not necessarily in synergy, there have been studies focused on a few select ILs and DESs for electrochemical reduction of CO2, often diluting them with aqueous or non-aqueous solvents. The resulting electrode–electrolyte interfaces present a complex speciation for RCC. In this review, we describe how the ILs and DESs are tuned for RCC and specifically address the CO2 chemisorption and electroreduction mechanisms. Critical bulk and interfacial properties of ILs and DESs are discussed in the context of RCC, and the potential of these electrolytes are presented through a techno-economic evaluation. [ABSTRACT FROM AUTHOR]

Platinum is known as the best catalyst for the hydrogen evolution reaction (HER) but the scarcity and high cost of Pt limit its widespread applicability. Herein, the role of the underlying substrate on the HER activity of dispersed Pt atoms is uncovered. A direct current magnetron sputtering technique is utilized to deposit transition metal (TM) thin films of W, Ti, and Ta as underlying substrates for extremely low loading of Pt (<1.5 at%). The electrocatalytic performance of as‐synthesized samples for the HER is examined in both alkali and acidic media. The results show that despite the low loading of Pt, the Pt/TM catalysts produce hydrogen at a rate comparable to that of pristine bulk Pt. Pt/TM catalysts also display good stability with less than 5% decay in performance after 10 h of continuous HER operation. Based on the computational study, the excellent performance is attributed to the modified electronic properties of the Pt atoms, offering ideal binding energy for HER due to interaction with the underlying substrates. This work provides a robust and industry‐friendly route toward designing efficient catalytic systems for important electrochemical reactions such as HER and others. [ABSTRACT FROM AUTHOR]

Batteries based on sodium superoxide and on potassium superoxide have recently been reported (1-3). However, there have been no reports of a battery based on lithium superoxide (Li[O.sub.2]), despite much research (4-8) into the lithium-oxygen (Li-[O.sub.2]) battery because of its potential high energy density. Several studies (9-16) of Li-[O.sub.2] batteries have found evidence of Li[O.sub.2] being formed as one component of the discharge product along with lithium peroxide ([Li.sub.2][O.sub.2]). In addition, theoretical calculations have indicated that some forms of Li[O.sub.2] may have a long lifetime (17). These studies also suggest that it might be possible to form Li[O.sub.2] alone for use in a battery. However, solid Li[O.sub.2] has been difficult to synthesize in pure form (18) because it is thermodynamically unstable with respect to disproportionation, giving [Li.sub.2][O.sub.2] (refs 19, 20). Here we show that crystalline Li[O.sub.2] can be stabilized in a Li-[O.sub.2] battery by using a suitable graphene-based cathode. Various characterization techniques reveal no evidence for the presence of [Li.sub.2][O.sub.2]. A novel templating growth mechanism involving the use of iridium nanoparticles on the cathode surface may be responsible for the growth of crystalline Li[O.sub.2]. Our results demonstrate that the Li[O.sub.2] formed in the Li-[O.sub.2] battery is stable enough for the battery to be repeatedly charged and discharged with a very low charge potential (about 3.2 volts). We anticipate that this discovery will lead to methods of synthesizing and stabilizing Li[O.sub.2], which could open the way to high-energy-density batteries based on Li[O.sub.2] as well as to other possible uses of this compound, such as oxygen storage., The crystalline Li[O.sub.2] reported here was made electrochemically using a cathode based on reduced graphene oxide (rGO) with added iridium (Ir) nanoparticles. Initially graphene oxide (GO) was prepared by a [...]