The concept of solid catalysts with ionic liquid layer (SCILL) originates from the field of heterogeneous catalysis, where it offers a unique way to regulate both the catalytic activity and ...selectivity. In recent years, applying this concept in electrocatalysis represented a new, exciting, and growing research field. Herein, emerging applications of the SCILL concept in the context of electrocatalysis for key energy storage/conversion processes such as oxygen reduction, oxygen evolution, and CO2 reduction reactions are comprehensively reviewed. Alongside case studies highlighting the history, development and latest progress of the SCILL concept, mechanistic underpinnings on the roles of ILs in each application are critically discussed. At the same time, the key challenges and future opportunities in fully leveraging the SCILL concept for either regulating the performance of electrocatalysts or gaining mechanistic understandings for those electrocatalytic processes with complex reaction pathways are outlined.
Engineering the microenvironments at electrochemical interfaces by following the concept of “solid catalysts with ionic liquid layer (SCILL)”, has emerged as a novel approach to regulating the performance of electrocatalysts. Herein, emerging applications of the SCILL concept in electrocatalytic processes are reviewed, aiming at providing guidelines for exploring the SCILL concept as a generic tool to maximize the efficiency of electrocatalysts.
Modifying Pt catalysts using hydrophobic ionic liquids (ILs) has been demonstrated to be a facile approach for boosting the performance of Pt catalysts for the oxygen reduction reaction (ORR). This ...work aims to deepen the understanding and initiate a rational molecular tuning of ILs for improved activity and stability. To this end, Pt/C catalysts were modified using a variety of 1-methyl-3-alkylimidazolium bis(trifluoromethanesulfonyl)imide (C n C1imNTf2, n = 2–10) ILs with varying alkyl chain lengths in imidazolium cations, and the electrocatalytic properties (e.g., electrochemically active surface area, catalytic activity, and stability) of the resultant catalysts were systematically investigated. We found that ILs with long cationic chains (C6, C10) efficiently suppressed the formation of nonreactive oxygenated species on Pt; however, at the same time they blocked active Pt sites and led to a lower electrochemically active surface area. It is also disclosed that the catalytic activity strongly correlates with the alkyl chain length of cations, and a distinct dependence of intrinsic activity on the alkyl chain length was identified, with the maximum activity obtained on Pt/C-C4C1imNTf2. The optimum arises from the counterbalance between more efficient suppression of oxygenated species formation on Pt surfaces and more severe passivation of Pt surfaces with elongation of the alkyl chain length in imidazolium cations. Moreover, the presence of an IL can also improve the electrochemical stability of Pt catalysts by suppressing the Pt dissolution, as revealed by combined identical-location transmission electron microscopy (TEM) and in situ inductively coupled plasma mass spectrometry (ICP-MS) analyses.
In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by ...internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well.
Developing cost‐effective electrocatalysts for the oxygen reduction reaction (ORR) is a prerequisite for broad market penetration of low‐temperature fuel cells. A major barrier stems from the ...poisoning of surface sites by nonreactive oxygenated species and the sluggish ORR kinetics on the Pt catalysts. Herein we report a facile approach to accelerating ORR kinetics by using a hydrophobic ionic liquid (IL), which protects Pt sites from surface oxidation, making the IL‐modified Pt intrinsically more active than its unmodified counterpart. The mass activity of the catalyst is increased by three times to 1.01 A mg−1Pt@0.9 V, representing a new record for pure Pt catalysts. The enhanced performance of the IL‐modified catalyst can be stabilized after 30 000 cycles. We anticipate these results will form the basis for an unprecedented perspective in the development of high‐performing electrocatalysts for fuel‐cell applications.
Keep my place: A hydrophobic ionic liquid phase helps protect the Pt sites from being poisoned by nonreactive oxygenated species, leading to dramatically improved kinetics of the oxygen reduction reaction (ORR) on platinum catalyst.
Summary
Outer membrane vesicles (OMVs) are asymmetrical single bilayer membranous nanostructures produced by Gram‐negative bacteria important for bacterial interaction with the environment. ...Porphyromonas gingivalis, a keystone pathogen associated with chronic periodontitis, produces OMVs that act as a virulence factor secretion system contributing to its pathogenicity. Despite their biological importance, the mechanisms of OMV biogenesis have not been fully elucidated. The ~14 times more curvature of the OMV membrane than cell outer membrane (OM) indicates that OMV biogenesis requires energy expenditure for significant curvature of the OMV membrane. In P. gingivalis, we propose that this may be achieved by upregulating the production of certain inner or outer leaflet lipids, which causes localized outward curvature of the OM. This results in selection of anionic lipopolysaccharide (A‐LPS) and associated C‐terminal domain (CTD) ‐family proteins on the outer surface due to their ability to accommodate the curvature. Deacylation of A‐LPS may further enable increased curvature leading to OMV formation. Porphyromonas gingivalis OMVs that are selectively enriched in CTD‐family proteins, largely the gingipains, can support bacterial coaggregation, promote biofilm development and act as an intercessor for the transport of non‐motile bacteria by motile bacteria. The P. gingivalis OMVs are also believed to contribute to host interaction and colonization, evasion of immune defense mechanisms, and destruction of periodontal tissues. They may be crucial for both micro‐ and macronutrient capture, especially heme and probably other assimilable compounds for its own benefit and that of the wider biofilm community.
Ionic liquids (ILs) modification, following the concept of “solid catalyst with ionic liquid layer (SCILL)”, has been demonstrated to be an effective approach to improving both activity and stability ...of Pt-based catalysts for the oxygen reduction reaction. In this work, the SCILL concept has been applied to a trimetallic PtNiMo/C system, which has been documented recently to be significantly advantageous over the benchmark PtNi-based catalysts for oxygen reduction. To achieve this, two hydrophobic ILs (BMIMNTF2 and MTBDBETI) were used to modify PtNiMo/C with four IL-loading amounts between 7 and 38 wt %. We found that the Pt mass activity (@0.9 V) could be improved by up to 50% with BMIMNTF2 and even 70% when MTBDBETI is used. Exceeding a specific IL loading amount, however, leads to a mass transport related activity drop. Moreover, it is also disclosed that both ILs can effectively suppress the formation of nonreactive oxygenated species, while at the same time imposing little effect on the electrochemical active surface area. For a deeper understanding of the degradation mechanism of pristine and IL modified PtNiMo/C, we applied identical location transmission electron microscopy and in situ scanning flow cell coupled to inductively coupled plasma mass spectrometry techniques. It is disclosed that the presence of ILs has selectively accelerated the dissolution of Mo and eventually results in a more severe degradation of PtNiMo/C. This shows that future research needs to identify ILs that prevent the Mo dissolution to leverage the potential of the IL modification of PtNiMo catalysts.
The key to fully leveraging the potential of the electrochemical CO2 reduction reaction (CO2RR) to achieve a sustainable solar‐power‐based economy is the development of high‐performance ...electrocatalysts. The development process relies heavily on trial and error methods due to poor mechanistic understanding of the reaction. Demonstrated here is that ionic liquids (ILs) can be employed as a chemical trapping agent to probe CO2RR mechanistic pathways. This method is implemented by introducing a small amount of an IL (BMImNTf2) to a copper foam catalyst, on which a wide range of CO2RR products, including formate, CO, alcohols, and hydrocarbons, can be produced. The IL can selectively suppress the formation of ethylene, ethanol and n‐propanol while having little impact on others. Thus, reaction networks leading to various products can be disentangled. The results shed new light on the mechanistic understanding of the CO2RR, and provide guidelines for modulating the CO2RR properties. Chemical trapping using an IL adds to the toolbox to deduce the mechanistic understanding of electrocatalysis and could be applied to other reactions as well.
The presence of a small amount of ionic liquid significantly alters the product spectrum of CO2 reduction over a Cu catalyst. The ionic liquid acts as a chemical trapping agent, selectively suppressing the formation of C2+ products that involve carbene as a key intermediate. The response in product distribution to ionic liquid modification offers a new way to disentangle the complex reaction network of CO2 reduction by Cu catalysts.
High cost and poor stability of the oxygen reduction reaction (ORR) electrocatalysts are the major barriers for broad-based application of polymer electrolyte membrane fuel cells. Here we report a ...facile and scalable approach to improve Pt/C catalysts for ORR, by modification with small amounts of hydrophobic ionic liquid (IL). The ORR performance of these IL-modified catalysts can be readily manipulated by varying the degree of IL filling, leading to a 3.4 times increase in activity. Besides, the IL-modified catalysts exhibit substantially enhanced stability relative to Pt/C. The enhanced performance is attributed to the optimized microenvironment at the interface of Pt and electrolyte, where advantages stemming from an increased number of free sites, higher oxygen concentration in the IL and electrostatic stabilization of the nanoparticles develop fully, at the same time that the drawback of mass transfer limitation remains suppressed. These findings open a new avenue for catalyst optimization for next-generation fuel cells.
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