With large quantities and natural resistance to degradation, plastic waste raises growing environmental concerns in the world. To achieve the upcycling of plastic waste into value-added products, the electrocatalyticdriven process is emerging as an attractive option due to the mild operation conditions, high reaction selectivity, and low carbon emission. Herein, this review provides a comprehensive overview of the upgrading of plastic waste via electrocatalysis. Specifically, key electrooxidation processes including the target products, intermediates and reaction pathways in the plastic electro-reforming process are discussed. Subsequently, advanced electrochemical systems, including the integration of anodic plastic monomer oxidation and value-added cathodic reduction and photoinvolved electrolysis processes, are summarized. The design strategies of electrocatalysts with enhanced activity are highlighted and catalytic mechanisms in the electrocatalytic oxidation of plastic waste are elucidated. To promote the electrochemistry-driven sustainable upcycling of plastic waste, challenges and opportunities are further put forward.
Three-dimensional stacked transistors based on Si/SiGe heterojunction are a potential candidate for future low-power and high-performance computing in integrated circuits. Observing and accurately measuring strain in Si/SiGe heterojunctions is critical to increasing carrier mobility and improving device performance. Transmission electron microscopy (TEM) with high spatial resolution and analytical capabilities provides technical support for atomic-scale strain measurement and promotes significant progress in strain mapping technology. This paper reviews atomic-scale strain analysis for advanced Si/SiGe heterostructure based on TEM techniques. Convergent-beam electron diffraction, nano-beam electron diffraction, dark-field electron holography, and high-resolution TEM with geometrical phase analysis, are comprehensively discussed in terms of spatial resolution, strain precision, field of view, reference position, and data processing. Also, the advantages and critical issues of these strain analysis methods based on the TEM technique are summarized, and the future direction of TEM techniques in the related areas is prospected.
With the advantages of similar theoretical basis to lithium batteries, relatively low budget and the abundance of sodium resources, sodium ion batteries (SIBs) are recognized as the most competitive alternative to lithium-ion batteries. Among various types of cathodes for SIBs, advantages of high theoretical capacity, nontoxic and facile synthesis are introduced for layered transition metal oxide cathodes and therefore they have attracted huge attention. Nevertheless, layered oxide cathodes suffer from various degradation issues. Among these issues, interface instability including surface residues, phase transitions, loss of active transition metal and oxygen loss takes up the major part of the degradation of layered oxides. These degradation mechanisms usually lead to irreversible structure collapse and cracking generation, which significantly influence the interface stability and electrochemical performance of layered cathodes. This review briefly introduces the background of researches on layered cathodes for SIBs and their basic structure types. Then the origins and effects on layered cathodes of degradation mechanisms are systematically concluded. Finally, we will summarize various interface modification methods including surface engineering, doping modification and electrolyte composition which are aimed to improve interface stability of layered cathodes, perspectives of future research on layered cathodes are mentioned to provide some theoretical proposals.
Photodetectors (PDs) are optoelectronic devices that convert optical signals into electrical responses. Recently, there has been a tremendous increase in research interest in PDs based on colloidal quantum dots (QDs) and two-dimensional (2D) material heterostructures owing to the strong light-absorption capacity and the well-adjustable band gap of QDs and the superior charge carriers transfer ability of 2D materials. In particular, the heterojunction formed between QDs and 2D materials can effectively enhance the separation and transport of photogenerated charge carriers, which is expected to establish PDs with ultrahigh photoconductive gain, high responsivity, and detectivity. This review aimed to summarize the state-of-the-art advances in the research of QDs/2D material nanohybrid PDs, including the device parameters, architectures, working mechanisms, and fabrication technologies. The progress of hybrid PDs based on the heterojunction of QDs with different 2D materials, along with their innovative applications, are comprehensively described. In the end, the challenges and feasible strategies in future research and development are briefly proposed.
3D perovskite materials are advancing rapidly in the field of photovoltaics and light-emitting diodes, but the development in field effect transistors (FETs) is limited due to their intrinsic ion migration. Ion migration in perovskite FETs can screen the electric field of the gate and affect its modulation, as well as influence the charge carriers transport, leading to non-ideal device characteristics and lower device stability. Here, we provide a concise review that explains the mechanism of ion migration, summarizes the strategies for suppressing ion migration, and concludes with a discussion of the future prospects for 3D perovskite FETs.
Nickel-rich cathode is considered to be the cathode material that can solve the short-range problem of electric vehicles with excellent electrochemical properties and low price. However, microcracks, lithium–nickel hybridization, and irreversible phase transitions during cycling limit their commercial applications. These issues should be resolved by modifications. In recent years, it has been favored by researchers to solve a large number of problems by combining multiple modification strategies. Therefore, this paper reviews recent developments in various modification techniques for nickel-rich cathode materials that have improved their electrochemical characteristics. The summary of multiple modifications of nickel-rich materials will play a guiding role in future development.
Metal–air batteries, fuel cells, and electrochemical H2O2 production currently attract substantial consideration in the energy sector owing to their efficiency and eco-consciousness. However, their broader use is hindered by the complex oxygen reduction reaction (ORR) that occurs at cathodes and involves intricate electron transfers. Despite the significant ORR performance of platinum-based catalysts, their high cost, operational limitations, and susceptibility to methanol poisoning hinder broader implementation. This emphasizes the need for efficient nonprecious metal-based ORR electrocatalysts. A promising approach involves utilizing single-atom catalysts (SACs) featuring metal–nitrogen– carbon (M-N-C) coordination sites. SACs offer advantages such as optimal utilization of metal atoms, uniform active centers, precisely defined catalytic sites, and robust metal–support interactions. However, the symmetrical electron distribution around the central metal atom of a single-atom site (M-N4) often results in suboptimal ORR performance. This challenge can be addressed by carefully tailoring the surrounding environment of the active center. This review specifically focuses on recent advancements in the Fe-N4 environment within Fe-N-C SACs. It highlights the promising strategy of coupling Fe-N4 sites with metal clusters and/or nanoparticles, which enhances intrinsic activity. By capitalizing on the interplay between Fe-N4 sites and associated species, overall ORR performance improved. The review combines findings from experimental studies and density functional theory simulations, covering synthesis strategies for Fe-N-C coupled synergistic catalysts, characterization techniques, and the influence of associated particles on ORR activity. By offering a comprehensive outlook, the review aims to encourage research into high-efficiency Fe single-atom sites coupled synergistic catalysts for real-world applications in the coming years.
In the present day, there is a growing trend of employing new strategies to synthesize hybrid nanoparticles, which involve combining various functionalities into a single nanocomposite system. These modern methods differ significantly from the traditional classical approaches and have emerged at the forefront of materials science. The fabrication of hybrid nanomaterials presents an unparalleled opportunity for applications in a wide range of areas, including therapy to diagnosis. The focus of this review article is to shed light on the different modalities of hybrid nanoparticles, providing a concise description of hybrid silver nanoparticles, exploring various modes of synthesis and classification of hybrid silver nanoparticles, and highlighting their advantages. Additionally, we discussed core-shell silver nanoparticles and various types of core and shell combinations based on the material category, such as dielectric, metal, or semiconductor. The two primary classes of hybrid silver nanoparticles were also reviewed. Furthermore, various hybrid nanoparticles and their methods of synthesis were discussed but we emphasize silica as a suitable candidate for hybridization alongside metal nanoparticles. This choice is due to its hydrophilic surface qualities and high surface charge, which provide the desired repulsive forces to minimize aggregation between the metal nanoparticles in the liquid solution. Silica shell encapsulation also provides chemical inertness, robustness and the adaptability to the desired hybrid nanoparticle. Therefore, among all the materials used to coat metal nanoparticles; silica is highly approved.
The industrial application of zinc-ion batteries is restricted by irrepressibledendrite growth and side reactions that resulted from the surfaceheterogeneity of the commercial zinc electrode and thethermodynamic spontaneous corrosion in a weakly acidic aqueouselectrolyte. Herein, a common polar dye, Procion Red MX-5b, with highpolarity and asymmetric charge distribution is introduced into the zincsulfate electrolyte, which can not only reconstruct the solvation configurationof Zn+2 and strengthen hydrogen bonding to reduce the reactivityof free H2O but also homogenize interfacial electric field by itspreferentially absorption on the zinc surface. The symmetric cell cancycle with a lower voltage hysteresis (78.4 mV) for 1120 times at5 mA cm−2 and Zn//NaV3O8·1.5H2O full cell can be cycled over 1000 times with high capacity (average 170 mAh g−1) at 4 A g−1 in the compoundelectrolyte. This study provides a new perspective for additiveengineering strategies of aqueous zinc-ion batteries.
Electrochemical hydrogen evolution reaction (HER) and overall water splitting (OWS) for renewable energy generation have recently become a highly promising and sustainable strategy to tackle energy crisis and global warming arising from our overreliance on fossil fuels. Previously, tremendous research breakthroughs have been made in 2D carbon-based heterostructured electrocatalysts in this field. Such heterostructures are distinguished by their remarkable electrical conductivity, exposed active sites, and mechanical stability. Herein, with fundamental mechanisms of electrocatalytic OWS summarized, our review critically emphasized on state-of-the-art 2D carbon nanosheet-, graphene-, and graphdiyne-based heterostructured electrocatalysts in HER and OWS since 2018. Particularly, the three emerging carbonaceous substrates tend to be incorporated with metal carbides, phosphides, dichalcogenides, nitrides, oxides, nanoparticles, single atom catalysts, or layered double hydroxides. Meanwhile, fascinating structural engineering and facile synthesis strategies were also unraveled to establish the structure–activity relationship, which will enlighten future electrocatalyst developments toward ameliorated HER and OWS activities. Additionally, computational results from density functional theory simulations were highlighted as well to better comprehend the synergistic effects within the heterostructures. Finally, current stages and future recommendations of this brand-new electrocatalyst type were concluded and discussed for advanced catalyst designs and future practical applications.
Efficient redox reactions of lean electrolyte lithium–sulfur (Li–S) batteries highly rely on rational catalyst design. Herein, we report an electrocatalyst based on N-doped carbon nanotubes (CNT)-encapsulated Ni nanoparticles (Ni@NCNT) as kinetics regulators for Li–S batteries to propel the polysulfide-involving multiphase transformation. Moreover, such a CNT-encapsulation strategy greatly prevents the aggregation of Ni nanoparticles and enables the extraordinary structural stability of the hybrid electrocatalyst, which guarantees its persistent catalytic activity on sulfur redox reactions. When used as a modified layer on a commercial separator, the Ni@NCNT interlayer contributes to stabilizing S cathode and Li anode by significantly retarding the shuttle effect. The corresponding batteries with a 3.5 mg cm-2 sulfur loading achieve the promising cycle stability with ∼85% capacity retention at the electrolyte/sulfur ratios of 5 and 3 µL mg-1. Even at a high loading of 12.2 mg cm-2, the battery affords an areal capacity of 7.5 mA h cm-2.
With exceptional capacity during high-voltage cycling, P3-type Nadeficient layered oxide cathodes have captured substantial attention. Nevertheless, they are plagued by severe capacity degradation over cycling. In this study, tuning and optimizing the phase composition in layered oxides through Li incorporation are proposed to enhance the high-voltage stability. The structural dependence of layered Na2/3LixNi0.25Mn0.75O2+δ oxides on the lithium content (0.0 ≤ x ≤ 1.0) offered during synthesis is investigated systematically on an atomic scale. Surprisingly, increasing the Li content triggers the formation of mixed P2/O3-type or P3/P2/O3-type layered phases. As the voltage window is 1.5–4.5 V, P3-type Na2/3Ni0.25Mn0.75O2 (NL0.0NMO,
Electrochemical water splitting for hydrogen generation is considered one of the most promising strategies for reducing the use of fossil fuels and storing renewable electricity in hydrogen fuel. However, the anodic oxygen evolution process remains a bottleneck due to the remarkably high overpotential of about 300 mV to achieve a current density of 10 mA cm-2. The key to solving this dilemma is the development of highly efficient catalysts with minimized overpotential, long-term stability, and low cost. As a new 2D material, MXene has emerged as an intriguing material for future energy conversion technology due to its benefits, including superior conductivity, excellent hydrophilic properties, high surface area, versatile chemical composition, and ease of processing, which make it a potential constituent of the oxygen evolution catalyst layer. This review aims to summarize and discuss the recent development of oxygen evolution catalysts using MXene as a component, emphasizing the synthesis and synergistic effect of MXene-based composite catalysts. Based on the discussions summarized in this review, we also provide future research directions regarding electronic interaction, stability, and structural evolution of MXene-based oxygen evolution catalysts. We believe that a broader and deeper research in this area could accelerate the discovery of efficient catalysts for electrochemical oxygen evolution.
The catalytic coordinate is essentially the evolving frontier orbital interaction while feeding with catalytic materials and adsorbates under proper reaction conditions. The heterogeneous catalytic reaction mechanism involves the initial adsorption and activation of reactants, subsequent intermediate transformation, final target product desorption, and regeneration of catalytic materials. In these catalytic processes, interaction modulations in terms of orbital hybridization/coupling allow an intrinsic control on both thermodynamics and kinetics. Concerned charge transfer and redistribution, orbital splitting and rearrangement with specific orientation, and spin change and crossover pose a formidable challenge on mechanism elucidation; it is hard to precisely correlate the apparent activity and selectivity, let alone rational modulations on it. Therefore, deciphering the orbital couplings inside a catalytic round is highly desirable and the dependent descriptor further provides in‐depth insights into catalyst design at the molecule orbital level. This review hopes to provide a comprehensive understanding on orbital hybridizations, modulations, and correlated descriptors in heterogeneous catalysis.
There has been a significant scope toward the cutting-edge investigations in hierarchical carbon nanostructured electrodes originating from cellulosic materials, such as cellulose nanofibers, available from natural cellulose and bacterial cellulose. Elements of energy storage systems (ESSs) are typically established upon inorganic/metal mixtures, carbonaceous implications, and petroleum-derived hydrocarbon chemicals. However, these conventional substances may need help fulfilling the ever-increasing needs of ESSs. Nanocellulose has grown significantly as an impressive 1D element due to its natural availability, eco-friendliness, recyclability, structural identity, simple transformation, and dimensional durability. Here, in this review article, we have discussed the role and overview of cellulose-based hydrogels in ESSs. Additionally, the extraction sources and solvents used for dissolution have been discussed in detail. Finally, the properties (such as self-healing, transparency, strength and swelling behavior), and applications (such as flexible batteries, fuel cells, solar cells, flexible supercapacitors and carbon-based derived from cellulose) in energy storage devices and conclusion with existing challenges have been updated with recent findings.