In recent years, the precisely controlled synthesis of chiral twisted molecular carbons has emerged as a forefront topic in the research of carbon materials. Molecular carbons refer to carbon nanomaterials synthesized with precision at the atomic level. Through rational design, rigid and stable chiral twisted structures can be synthesized. The exploration in the field of chiral twisted molecular carbons is key to fully understanding the various twisted configurations of carbon materials and delving into the relationship between structure design and functionality. This review explores chiral twisted configurations of carbon nanomaterials such as nanographene, carbon nanobelts, carbon nanosheets, graphdiyne, etc. It emphasizes the role of photocyclization, Scholl reaction, and Diels–Alder reactions in achieving precise chiral control and discusses a range of innovative design strategies. These strategies have led to the development of various twisted structures, such as helical, propeller, and Möbius strip configurations. The introduction of chirality, combined with the inherent exceptional optical properties of nanocarbon materials, has facilitated the creation of materials with superior chiroptical performances. This advancement is driving applications in fields such as optoelectronics and chiral optics.
To unveil the nature of amorphous states, single-element amorphous metals have been the perfect research subject due to the simplest composition. However, the extreme crystal nucleation and growth rate in single-element metal make the synthesis of single-element amorphous metals seemingly impossible in the past. Fortunately, benefited by several delicate synthetic strategies developed recently, the single-element amorphous metals have been successfully demonstrated. This review aims to provide a systematic overview of the synthesis of single-element amorphous metals covering the challenges in physics and recent achievements. In addition, current understanding of the atomic and electronic structures of single-element amorphous metal has also been included. Finally, the challenges that worth further investigation are discussed. By identifying the potential avenues for further exploration, this review aims to contribute valuable insights that will propel the cognition of single-element amorphous metals.
Electrocatalysis, which involves oxidation and reduction reactions with direct electron transfer, is essential for a variety of clean energy conversion devices. Currently, the vast majority of studies regarding electrocatalysis reactions focus on strong acidic or alkaline media because of the higher catalytic activity. Nevertheless, some inherent drawbacks, including the corrosive environment, expensive proton exchange membranes, and side effects, are still hard to break through. A sustainably promising way to overcome these shortcomings is to deploy neutral/near-neutral electrolytes for electrocatalysis reactions. Unfortunately, insufficient research in this area due to the lack of attention to related issues has slowed down the development process. In this review, we systematically review the catalytic reaction mechanisms, neutral electrolytes, electrocatalysts, and modification strategies carried out in neutral media on the three most common electrocatalytic reactions, that is, hydrogen evolution reaction, oxygen reduction reaction, and oxygen evolution reaction. Furthermore, the advanced characterization tools for guiding catalyst synthesis and mechanistic studies are also summarized. Eventually, we propose some challenges and perspectives on electrocatalysis reactions in neutral media and hope it will attract more research interest and provide guidance in neutral electrocatalysis.
The critical challenges of the energy crisis and environmental degradation promote innovative approaches for energy conversion. Semiconductor-based photocatalytic technology, which transforms solar energy into chemical energy, emerges as a promising solution. However, the practical application of this technology faces several challenges, such as the rapid recombination of photogenerated electrons and holes, significantly limiting photocatalytic efficiency. In this review, we provide a detailed discussion, an insightful perspective, and a critical evaluation of recent advances, challenges, and opportunities in the field of photocatalysis using polar materials. We present a comprehensive examination of the photocatalytic mechanisms, activity, and diverse applications of photocatalysts based on polar materials. We also briefly discuss the engineering design of polar photocatalysis in experiments and its scalability in the industry. This review outlines future trends and potential breakthroughs in the photocatalytic field using polar materials, projecting their transformative impact on environmental chemistry and energy engineering.
Room-temperature sodium-sulfur (RT Na-S) batteries are a promising next-generation energy storage device due to their low cost, high energy density (1274 Wh kg-1), and environmental friendliness. However, RT Na-S batteries face a series of vital challenges from sulfur cathode and sodium anode: (i) sluggish reaction kinetics of S and Na2S/Na2S2; (ii) severe shuttle effect from the dissolved intermediate sodium polysulfides (NaPSs); (iii) huge volume expansion induced by the change from S to Na2S; (iv) continuous growth of sodium metal dendrites, leading to short-circuiting of the battery; (v) huge volume expansion/contraction of sodium anode upon sodium plating/stripping, causing uncontrollable solid-state electrolyte interphase growth and “dead sodium” formation. Various strategies have been proposed to address these issues, including physical/chemical adsorption of NaPSs, catalysts to facilitate the rapid conversion of NaPSs, high-conductive materials to promote ion/electron transfer, good sodiophilic Na anode hetero-interface homogenized Na ions flux and three-dimensional porous anode host to buffer the volume expansion of sodium. Heterostructure materials can combine these merits into one material to realize multifunctionality. Herein, the recent development of heterostructure as the host for sulfur cathode and Na anode has been reviewed. First of all, the electrochemical mechanisms of sulfur cathode/sodium anode and principles of heterostructures reinforced Na-S batteries are described. Then, the application of heterostructures in Na-S batteries is comprehensively examined. Finally, the current primary avenues of employing heterostructures in Na-S batteries are summarized. Opinions and prospects are put forward regarding the existing problems in current research, aiming to inspire the design of advanced and improved next-generation Na-S batteries.
Alkaline hydrogen evolution reaction (HER) for scalable hydrogen production largely hinges on addressing the sluggish bubble-involved kinetics on the traditional Ni-based electrode, especially for ampere-level current densities and beyond. Herein, 3D-printed Ni-based sulfide (3DPNS) electrodes with varying scaffolds are designed and fabricated. In situ observations at microscopic levels demonstrate that the bubble escape velocity increases with the number of hole sides (HS) in the scaffolds. Subsequently, we conduct multiphysics field simulations to illustrate that as the hole shapes transition from square, pentagon, and hexagon to circle, where a noticeable reduction in the bubble-attached HS length and the pressure balance time around the bubbles results in a decrease in bubble size and an acceleration in the rate of bubble escape. Ultimately, the 3DPNS electrode with circular hole configurations exhibits the most favorable HER performance with an overpotential of 297 mV at the current density of up to 1000 mA cm-2 for 120 h. The present study highlights a scalable and effective electrode scaffold design that promotes low-cost and low-energy green hydrogen production through the ampere-level alkaline HER.
Exploration of metastable phases holds profound implications for functional materials. Herein, we engineer the metastable phase to enhance the thermoelectric performance of germanium selenide (GeSe) through tailoring the chemical bonding mechanism. Initially, AgInTe2 alloying fosters a transition from stable orthorhombic to metastable rhombohedral phase in GeSe by sbstantially promoting p-state electron bonding to form metavalent bonding (MVB). Besides, extra Pb is employed to prevent a transition into a stable hexagonal phase at elevated temperatures by moderately enhancing the degree of MVB. The stabilization of the metastable rhombohedral phase generates an optimized bandgap, sharpened valence band edge, and stimulative band convergence compared to stable phases. This leads to decent carrier concentration, improved carrier mobility, and enhanced density-of-state effective mass, culminating in a superior power factor. Moreover, lattice thermal conductivity is suppressed by pronounced lattice anharmonicity, low sound velocity, and strong phonon scattering induced by multiple defects. Consequently, a maximum zT of 1.0 at 773 K is achieved in (Ge0.98Pb0.02Se)0.875(AgInTe2)0.125, resulting in a maximum energy conversion efficiency of 4.90% under the temperature difference of 500 K. This work underscores the significance of regulating MVB to stabilize metastable phases in chalcogenides.
Along with the constantly evolving functional microsystems toward more diversification, the more rigorous design deliberation of pursuing higher mass-loading of electrode materials and low-temperature fabrication compatibility have imposed unprecedented demand on integrable all-solid-state thin-film microbatteries. While the classic thin-film intercalation cathode prepared by vacuum-based techniques inevitably encountered a post-annealing process, tape-casting technologies hold great merits both in terms of high-mass loading and low-temperature processing. In this work, a novel microbattery configuration is developed by the combination of traditional tape-casting thick electrodes and sputtered inorganic thin-film solid electrolytes (∼3 µm lithium phosphorus oxynitride). Enabled by physically pressed or vapor-deposited Li as an anode, solid-state batteries with tape-casted LiFePO4 electrodes exhibit outstanding cyclability and stability. To meet integration requirements, LiFePO4/LiPON/Si microbatteries were successfully fabricated at low temperatures and found to achieve a wide operating temperature range. This novel configuration has good prospects in promoting the thin-film microbattery enabling a paradigm shift and satisfying diversified requirements.