A Chain-Growth Mechanism for Conjugated Polymer Synthesis Facilitated by Dinuclear Complexes with Redox-Active Ligands.

Conjugated polymers are widely used in energy conversion and sensor applications, but their synthesis relies on imprecise step‐growth or narrow‐scope chain‐growth methods, typically based on transition metal (TM)‐catalyzed cross‐coupling. Here we report that a dinickel complex with a redox‐active naphthyridine diimine ligand accesses new chain‐growth mechanistic manifolds for both donor and acceptor conjugated polymers, represented by poly(3‐hexylthiophene), poly(2,3‐bis(2‐ethylhexyl)thienopyrazine), and poly(2‐(2‐octyldodecyl)benzotriazole). For the latter, our method is particularly effective: we achieve high degrees of polymerization (DP) (>100) with moderate dispersities (Đ) of ≈1.4. Mechanistic analysis supports a radical/radical anion chain‐growth mechanism with organometallic intermediates instead of TM‐catalyzed cross‐couplings. Hence, our work develops new mechanisms for conjugated polymer synthesis and furnishes insights about the elementary reactivity of dinuclear complexes.

Nanoscale material designis crucial to the development of efficient renewable energy and storage technologies. While conventional research paradigms have emphasized material morphology, crystal polymorphs, and defect engineering, recent years have witnessed an emerging research interest in crystal orientation engineering since it can exploit anisotropic material properties to significantly enhance emerging energy storage and conversion applications. Herein, a comprehensive review of engineering the crystal orientation of materials to improve various energy conversion and storage technologies is provided. First, we discuss the effect of crystal orientation on material properties, including electrical conductivity, dielectric constant, surface energy, surface electronic structure, atom/molecule adsorption ability, and ionic conductivity. Then, the techniques to characterize the crystal orientation, including X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, and optical microscopy, are reviewed. After that, effectivestrategies to engineer crystal orientation using both bottom-up and top-down approaches are summarized. The advances in crystal orientation engineering in energy conversion (electrocatalysis, solar cells, and nanogenerators) and storage (metal anodes, non-metal-based electrode materials, and solid electrolytes) applications are subsequently discussed. Finally, future perspectives on the potential of crystal orientation engineering and its impact on emerging energy transition technologies are summarized.

Since the initial MXenes were discovered in 2011, several MXene compositions constructed using combinations of various transition metals have been developed. MXenes are ideal candidates for different applications in energy conversion and storage, because of their unique and interesting characteristics, which included good electrical conductivity, hydrophilicity, and simplicity of large-scale synthesis. Herein, we study the current developments in two-dimensional (2D) MXene nanosheets for energy storage and conversion technologies. First, we discuss the introduction to energy storage and conversion devices. Later, we emphasized on 2D MXenes and some specific properties of MXenes. Subsequently, research advances in MXene-based electrode materials for energy storage such as supercapacitors and rechargeable batteries is summarized. We provide the relevant energy storage processes, common challenges, and potential approaches to an acceptable solution for 2D MXene-based energy storage. In addition, recent advances for MXenes used in energy conversion devices like solar cells, fuel cells and catalysis is also summarized. Finally, the future prospective of growing MXene-based energy conversion and storage are highlighted.

Developing efficient multifunctional materials for the oxygen evolution reaction (OER) and supercapacitors has become essential for storing and converting energy. Taking advantage of the structural flexibility of metal–organic frameworks (MOFs), bifunctional electrochemical nanomaterial LaFeCoOOH with high performance is successfully synthesized by doping rare earth La atoms in transition metals. La doping modifies the coordination environment of active sites and material morphology, modulates the energy structure, improves material conductivity, and optimizes the adsorption and desorption performance of oxygen intermediates. LaFeCoOOH demonstrates exceptional electrocatalytic activity for OER, achieving a remarkably low overpotential of 177 mV at 10 mA cm −2 current density in 1 m KOH alkaline electrolyte. The material exhibits outstanding operational stability, maintaining consistent performance for over 1000 h at an elevated current density of 100 mA cm −2 under identical alkaline conditions. Furthermore, LaFeCoOOH electrode displays superior electrochemical energy storage capabilities, demonstrating an impressive specific capacitance of 3508 mF cm −2 at 1 mA cm −2 current density. When configured as an asymmetric supercapacitor (LaFeCoOOH//Activated Carbon (AC)) using 6 m KOH electrolyte, the device achieves an exceptional energy density of 118.52 µWh cm −2 while delivering a power density of 1700 µW cm −2 , highlighting its dual functionality for both energy conversion and storage applications. Hence, this study provides a new perspective for the exploration of new multifunctional transition metal composites modified with rare earth elements for energy storage and conversion applications.

Recent advances in the synthesis and modification of carbon-based 2D materials for application in energy conversion and storage

Recent insights into heterometal-doped copper oxide nanostructure-based catalysts for renewable energy conversion and generation

Dynamic wetting is a process that one fluid replaces the other fluid (usually gas) on solid surfaces, which is very common and widely involved in our daily activities and many industrial applications, such as printing, dyeing, coating, drag reduction, and many others. Due to the complexity of the dynamic wetting, most of studies have focused on understanding the dynamic wetting behaviors of simple fluids on homogeneous flat surfaces without any external fields in early ages. The gaps between the research with ideal wetting conditions and real applications facilitate the studies of dynamic wetting with complex conditions, such as complex fluids (non-Newtonian fluids, colloidal solutions, nanofluids etc.), real substrates (hydrophobic surfaces, hydrophilic surfaces, micro-nano hybrid surfaces or others), and complex external fields (electric fields, thermal fields or magnetic fields). Among these studies, the dynamic wetting with external electric fields, also known as electrowetting, is a hot topic. Electrowetting is a modification method of the surface wettability using an applied electric field. Electrowetting has been widely used in many microfluidic systems, such as electronic microlenses, electronic-paper, electrowetting display and others. This paper provides a review on the recent developments of electrowetting applications in the emerging micro-nano energy conversion and utilization systems, ranging from the physical and theoretical research, fundamental applications to industrial applications. The fundamental physical concepts and principles involved in electrowetting phenomena are reviewed in the first part. The mainstream physical mechanisms related to electrowetting are summarized and compared to illustrate their successes and limitations. The challenges in the topic of electrowetting phenomena are summarized, which lie in four aspects: (1) the contact angle saturation; (2) the contact angle hysteresis; (3) the electric puncture & electrolysis; (4) electrowetting reversibility on super-hydrophobic surfaces. This paper also reviews and summarizes the new achievements and contributions on material, structure and complex external conditions related to electrowetting applications. The gaps between electrowetting fundamental research and industrial applications lie in several facts, including the new electrowetting materials with low triggered electric field strength, the novel structures which can easily manipulate the liquid transport using electrowetting. Among the electrowetting structures, the “sandwich” style, the open-style, the twins-style, as well as the pole-array-style are summarized to illustrate their advantages and disadvantages. The liquid manipulation, the complex inner flows and the droplet vibration with external electric fields using electrowetting provide potential applications in the energy conversion or thermal management devices. There have been some pioneering studies on micro-nano energy conversion and utilization systems using electrowetting. The latest development on the research of the applications in the micro-nano energy conversion and utilization systems is reviewed, including micro-channel systems, electronic cooling, phase change and solar photovoltaic system applications. The outlooks on the topic of electrowetting are provided in end of this review, including: (1) new materials and EWOD (electrowetting-on-dielectric) structures; (2) electrowetting of complex fluids containing functional particles; (3) electrowetting coupled with thermal field or magnetic field; (4) enhancing boiling and condensation heat transfer using electrowetting; (5) smart thermal management methods using electrowetting.

Understanding the properties and behavior of carbon materials is of paramount importance in the pursuit of sustainable energy solutions and technological advancements. As versatile and abundant resources, carbon materials play a central role in various energy conversion and storage applications, making them essential components in the transition toward a greener and more efficient future. This study explores the impact of diammonium hydrogen phosphate (DAHP) impregnation on activated carbon fibers (ACFs) for efficient energy storage and conversion applications. The viscose fibers were impregnated with varying DAHP concentrations, followed by carbonization and activation processes. The capacitance measurements were conducted in 6 mol dm−3 KOH, 0.5 mol dm−3 H2SO4, and 2 mol dm−3 KNO3 solutions, while the oxygen reduction reaction (ORR) measurements were performed in O2-saturated 0.1 mol dm−3 KOH solution. We find that the presented materials display specific capacitances up to 160 F g−1 when the DAHP concentration is in the range of 1.0 to 2.5%. Moreover, for the samples with lower DAHP concentrations, highly selective O2 reduction to peroxide was achieved while maintaining low ORR onset potentials. Thus, by impregnating viscose fibers with DAHP, it is possible to tune their electrochemical properties while increasing the yield, enabling the more sustainable and energy-efficient synthesis of advanced materials for energy conversion applications.

This Tutorial teaches the essential development of nitrogen-plasma-assisted molecular-beam-epitaxy grown InGaN nanowires as an application-inspired platform for energy harvesting and conversion applications by growing dislocation- and strain-relieved axial InGaN-based nanowires. The Tutorial aims to shed light on the interfacial, surface, electrical, and photoelectrochemical characteristics of InGaN nanowires through nanoscale and ultrafast characterizations. Understanding the interrelated optical-physical properties proved critical in the development of renewable-energy harvesting and energy conversion devices. Benefiting from their unique aspect ratio and surface-to-volume ratio, semiconductor properties, and piezoelectric properties, the group-III-nitride nanowires, especially InGaN nanowires, are promising for clean energy conversion applications, including piezotronic/piezo-phototronic and solar-to-clean-fuel energy-conversion.

In recent years, intensive studies on thermal control devices have been conducted for the thermal management of electronics and computers as well as for applications in energy conversion, chemistry, sensors, buildings, and outer space. Conventional cooling or heating techniques realized using traditional thermal resistors and capacitors cannot meet the thermal requirements of advanced systems. Therefore, new thermal control devices are being investigated to satisfy these requirements. These devices include thermal diodes, thermal switches, thermal regulators, and thermal transistors, all of which manage heat in a manner analogous to how electronic devices and circuits control electricity. To design or apply these novel devices as well as thermal control principles, this paper presents a systematic and comprehensive review of the state‐of‐the‐art of fluidic and mechanical thermal control devices that have already been implemented in various applications for different size scales and temperature ranges. Operation principles, working parameters, and limitations are discussed and the most important features for a particular device are identified.

Nanoparticle suspensions represent a promising route toward low cost, large area solution deposition of functional thin films for applications in energy conversion, flexible electronics, and sensors. However, parameters such size, stoichiometry, and electronic properties must be controlled to achieve best results for the target application. In this report, we demonstrate that such control can be achieved viain situchemical oxidation ofMoOxnanoparticles in suspensions. Starting from a microwave-synthesized suspension of ultrasmall (d~2 nm)MoOxnanoparticles in n-butanol, we added H2O2at room temperature to chemically oxidize the nanoparticles. We systematically varied H2O2concentration and reaction time and found that they significantly affected oxidation state and work function ofMoOxnanoparticle films. In particular, we achieved a continuous tuning ofMoOxwork function from 4.4 to 5.0 eV, corresponding to oxidation of as-synthesizedMoOxnanoparticle (20% Mo6+) to essentially pure MoO3. This was achieved without significantly modifying nanoparticle size or stability. Such precise control ofMoOxstoichiometry and work function is critical for the optimization ofMoOxnanoparticles for applications in organic optoelectronics. Moreover, the simplicity of the chemical oxidation procedure should be applicable for the development of other transition oxide nanomaterials with tunable composition and properties.

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The oxidation of ammonia is an essential process in the nitrogen cycle, with important applications in energy conversion ("ammonia electrolysis"), environmental protection (removal of ammonia from waste streams), electrosynthesis (hydroxylamine production via nitrate or nitric oxide reduction) or sensors (ammonia sensors for a wide range of applications). The conversion of ammonia to nitrogen gas, which is the desirable process in most of these applications, is typically difficult to achieve even though N2 is thermodynamically the most favorable product. Among the three basal planes of platinum, Pt(100) is unique in converting ammonia selectively to nitrogen. This presentation deals with the mechanism of the ammonia oxidation on the Pt(100) single-crystal electrode in alkaline solutions, investigated by basic electrochemical methods coupled with in-situ infrared spectroscopy and online electrochemical mass spectrometry. Our study particularly focuses on the nature of the adsorbed intermediate species and thereby on their role in the N-N coupling and in the observed deactivation. Acknowledgments This research was supported by a Marie Curie International Outgoing Fellowship within the 7th European Community Framework Programme to Ioannis Katsounaros under Award IOF-327650, and by the U.S. Department of Energy, Office of Science, Materials Sciences and Engineering Division.

Piezoelectric materials are materials that can convert mechanical stress into electric charge, or vice versa. They have a unique crystal structure that allows them to exhibit this effect. Piezoelectric materials have wide applications in energy conversion, sensors, drives, and frequency control. In this review, we will introduce the basic principles and properties of piezoelectric materials, and discuss the different types and categories of piezoelectric materials based on their composition, structure, and performance. We will also highlight some of the current and emerging applications of piezoelectric materials in various fields and industries.

This review focuses on side-chain functionalized polymers derived from direct (co)polymerization of fluorescent dyes. This overview about polymerizable dyes includes 1,8-naphthalimides, fluoresceins, rhodamines, coumarins, azo-dyes, oxadiazoles, diverse aromatic dyes as well as selected other dyes that cannot be classified within these groups. The discussed dyes have been functionalized with a polymerizable unit in order to apply straight-forward polymerization procedures. Therefore, the center of attention is set to the optical properties of the polymerizable dyes and the applicable polymerization techniques. Furthermore, the various applications (i.e., in biomedicine and pharmacy, as thermo-responsive materials and energy transfer materials, for dispersion of carbon nanotubes and others) of each polymer are discussed.