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Ammonia is of emerging interest as a liquefied, renewable-energy-sourced energy carrier for global use in the future. Electrochemical reduction of N 2 (NRR) is widely recognised as an alternative to the traditional Haber–Bosch production process for ammonia. However, though the challenges of NRR experiments have become better understood, the reported rates are often too low to be convincing that reduction of the highly unreactive N 2 molecule has actually been achieved. This perspective critically reassesses a wide range of the NRR reports, describes experimental case studies of potential origins of false-positives, and presents an updated, simplified experimental protocol dealing with the recently emerging issues. Discovering a sustainable route to ammonia as a fertiliser and as an energy carrier is critically important, but many recent reports on the electrochemical nitrogen reduction are false positives. Here the authors uncover the emerging experimental traps and detail protocols to reliably avoid them.

Ammonia (NH 3 ) is one of the most widely produced chemicals worldwide. It has application in the production of many important chemicals, particularly fertilizers. It is also, potentially, an important energy storage intermediate and clean energy carrier. Ammonia production, however, mostly uses fossil fuels and currently accounts for more than 1.6% of global CO 2 emissions (0.57 Gt in 2015). Here we describe a solar-driven nanostructured photoelectrochemical cell based on plasmon-enhanced black silicon for the conversion of atmospheric N 2 to ammonia producing yields of 13.3 mg m −2  h −1 under 2 suns illumination. The yield increases with pressure; the highest observed in this work was 60 mg m −2  h −1 at 7 atm. In the presence of sulfite as a reactant, the process also offers a direct solar energy route to ammonium sulfate, a fertilizer of economic importance. Although the yields are currently not sufficient for practical application, there is much scope for improvement in the active materials in this cell. In nature, nitrogen fixation is achieved via light-dependent nitrogenases, but industrial photochemical conversion of nitrogen into ammonia has so far proven inefficient. Here, the authors describe a nanostructured black silicon photoelectrochemical cell that can catalyse the process using solar energy.

Ammonia is a widely produced chemical that is the basis of most fertilisers. However, it is currently derived from fossil fuels and there is an urgent need to develop sustainable approaches to its production. Ammonia is also being considered as a renewable energy carrier, allowing efficient storage and transportation of renewables. For these reasons, the electrochemical nitrogen reduction reaction (NRR) is currently being intensely investigated as the basis for future mass production of ammonia from renewables. This Perspective critiques current steps and miss-steps towards this important goal in terms of experimental methodology and catalyst selection, proposing a protocol for rigorous experimentation. We discuss the issue of catalyst selectivity and the approaches to promoting the NRR over H 2 production. Finally, we translate these mechanistic discussions, and the key metrics being pursued in the field, into the bigger picture of ammonia production by other sustainable processes, discussing benchmarks by which NRR progress can be assessed. The electrochemical reduction of nitrogen is being intensely investigated as the basis for future ammonia production. This Perspective critiques current steps and missteps towards this goal in terms of experimental methodology and catalyst selection, proposing a protocol for rigorous experimentation.

Written by experts who have been part of this field since its beginnings in both research and academia, this textbook introduces readers to this evolving topic and the broad range of applications that are being explored. The book begins by examining what it is that defines ionic liquids and what sets them apart from other materials. Chapters describe the various types of ionic liquids and the different techniques used to synthesize them, as well as their properties and some of the methods used in their measurement. Further chapters delve into synthetic and electrochemical applications and their broad use as \"Green\" solvents. Final chapters examine important applications in a wide variety of contexts, including such devices as solar cells and batteries, electrochemistry, and biotechnology. The result is a must-have resource for any researcher beginning to work in this growing field, including senior undergraduates and postgraduates.

Negative carbon emission technologies are critical for ensuring a future stable climate. However, the gaseous state of CO 2 does render the indefinite storage of this greenhouse gas challenging. Herein, we created a liquid metal electrocatalyst that contains metallic elemental cerium nanoparticles, which facilitates the electrochemical reduction of CO 2 to layered solid carbonaceous species, at a low onset potential of −310 mV vs CO 2 /C. We exploited the formation of a cerium oxide catalyst at the liquid metal/electrolyte interface, which together with cerium nanoparticles, promoted the room temperature reduction of CO 2 . Due to the inhibition of van der Waals adhesion at the liquid interface, the electrode was remarkably resistant to deactivation via coking caused by solid carbonaceous species. The as-produced solid carbonaceous materials could be utilised for the fabrication of high-performance capacitor electrodes. Overall, this liquid metal enabled electrocatalytic process at room temperature may result in a viable negative emission technology. While CO 2 reduction proves an appealing means to convert greenhouse emissions to high-value products, there are few materials capable of such a conversion. Here, the authors demonstrate a liquid-metal electrocatalyst to convert CO 2 directly into solid carbon that can be used as capacitor electrodes.

Why not consider liquid salt forms of active pharmaceutical ingredients (APIs) as an alternative versatile tool in the pharmaceutical industry? Recent developments have shown that known APIs can be readily converted into ionic liquids and that these novel phases often possess different properties (e.g., improved solubilities and dissolution rates), which may have a direct impact on the pharmacokinetics and pharmacodynamics of the drug. They may also offer the potential of novel and more efficient delivery modes, as well as patent protection for each of the new forms of the drug. Since these pharmaceutically active ionic liquids represent a thermodynamically stable phase, they avoid the troublesome issues surrounding polymorphism and “polymorphic transformation.” In some cases, an active cation and an active anion can be combined to produce a liquid possessing dual functionality. Here we examine and challenge the current industry reliance on crystalline APIs by discussing the breadth and potential impact of liquid salts as a possible approach to phase control.

The air electrode, which reduces oxygen (O₂), is a critical component in energy generation and storage applications such as fuel cells and metal/air batteries. The highest current densities are achieved with platinum (Pt), but in addition to its cost and scarcity, Pt particles in composite electrodes tend to be inactivated by contact with carbon monoxide (CO) or by agglomeration. We describe an air electrode based on a porous material coated with poly(3,4-ethylenedioxythiophene) (PEDOT), which acts as an O₂ reduction catalyst. Continuous operation for 1500 hours was demonstrated without material degradation or deterioration in performance. O₂ conversion rates were comparable with those of Pt-catalyzed electrodes of the same geometry, and the electrode was not sensitive to CO. Operation was demonstrated as an air electrode and as a dissolved O₂ electrode in aqueous solution.

Phenologists track the seasonal behavior of plants and animals in response to climatic change. During the second half of the twentieth century, phenologists developed a large-scale project to monitor the flowering time of the common lilac (Syringa vulgaris) across the United States. By the 1960s, this approach offered a potential plant-based indicator of anthropogenic climate change, a biological signal amidst the emerging narrative of increasing levels of atmospheric carbon dioxide. As a tangible representation of changes in climate—warmer temperatures lead to earlier blooming—phenology proved highly legible to scientists, politicians, and laypeople. Yet, as phenology gained broader repute in the 1960s, both in agricultural stations and as a component program of the International Biological Program (IBP), it struggled to align itself epistemically with the regnant disciplinary assumptions of mid-century ecology. Operating in the hinterlands between laboratory and field, biology and meteorology, ecological theory and agronomy practice, phenologists challenged prevailing notions of the model organism and what it meant to study biology in the field. Rebranding the discipline as a component of ecosystem modeling, scientists successfully brought phenology within the purview of mainstream ecology. In so doing, however, they obscured its climate-relevant meteorological character and stymied the development of a biological narrative of climate change.

Micelles formed by the self-assembly of block copolymers in selective solvents have attracted widespread attention and have uses in a wide variety of fields, whereas applications based on their electronic properties are virtually unexplored. Herein we describe studies of solution-processable, low-dispersity, electroactive fibre-like micelles of controlled length from π-conjugated diblock copolymers containing a crystalline regioregular poly(3-hexylthiophene) core and a solubilizing, amorphous regiosymmetric poly(3-hexylthiophene) or polystyrene corona. Tunnelling atomic force microscopy measurements demonstrate that the individual fibres exhibit appreciable conductivity. The fibres were subsequently incorporated as the active layer in field-effect transistors. The resulting charge carrier mobility strongly depends on both the degree of polymerization of the core-forming block and the fibre length, and is independent of corona composition. The use of uniform, colloidally stable electroactive fibre-like micelles based on common π-conjugated block copolymers highlights their significant potential to provide fundamental insight into charge carrier processes in devices, and to enable future electronic applications. The self-assembly of block copolymers to form micelles has been used in applications such as drug delivery and composite reinforcement. Here the authors explore the use of fibre-like micelles of controlled length in the active layer of field-effect transistor devices.

Electrochemical water splitting in acidic conditions offers important advantages over that in alkaline systems, but the technological progress is limited by the lack of inexpensive and efficient anode catalysts that can stably operate at a low pH and elevated temperature. Here we demonstrate oxygen evolution catalysts that are based on non-noble metals, are formed in situ during electrooxidation of acidic water and exhibit a high stability in operation due to a self-healing mechanism. The highly disordered mixed metal oxides generated from dissolved cobalt, lead and iron precursors sustain high water oxidation rates at reasonable overpotentials. Moreover, utilizing a sufficiently robust electrode substrate allows for a continuous water oxidation at temperatures up to 80 °C and rates up to 500 mA cm −2 at overpotentials below 0.7 V with an essentially flat support and with no loss in activity. This robust operation of the catalysts is provided by the thermodynamically stable lead oxide matrix that accommodates homogeneously distributed catalytic dopants. Electrochemical water splitting in acidic conditions is limited by the lack of inexpensive and stable anode catalysts. Now, Simonov and colleagues report a non-noble metal-based oxygen evolution catalyst formed in situ that exhibits high stability for acidic water oxidation due to a self-healing mechanism.