Engineering of geometrical configurations in dual-atom catalysts for electrocatalytic applications

Geometrical configurations play a crucial role in dual-atom catalysts(DACs)for electrocatalytic applications.Significant progress has been made to design DACs electrocatalysts with various geometri-cal configurations,but in-depth understanding the relationship between geometrical configurations and metal-metal interaction mechanisms for designing targeted DACs is still required.In this review,the recent progress in engineering of geometrical configurations of DACs is systematically summarized.Based on the polarity of geometrical configuration,DACs can be classified into two different types that are homonuclear and heteronuclear DACs.Furthermore,with regard to the geometrical configurations of the active sites,homonuclear DACs are identified into adjacent and bridged configurations,and heteronuclear DACs can be classified into adjacent,bridged,and separated configurations.Subsequently,metal-metal interactions in DACs with different geometrical configurations are introduced.Additionally,the applications of DACs in different electrocatalytic reactions are discussed,including the oxygen reduction reaction(ORR),oxygen evolution reaction(OER),hydrogen evolution reaction(HER),and other catalysis.Finally,the future challenges and perspectives for advancements in DACs are high-lighted.This review aims to provide inspiration for the design of highly effcient DACs towards energy relatedapplications.

Multiscale confinement nitridation in molybdenum carbide for efficient hydrogen production

The molybdenum carbide(Mo_(2)C)has been regarded as one of the most cost-efficient and stable electrocatalyst for the hydrogen evolution reaction(HER)by the virtue of its Pt-like electronic structures.However,the inherent limitation of high density of empty valence band significantly reduces its catalytic reactivity by reason of strong hydrogen desorption resistance.Herein,we propose a multiscale confinement synthesis method to design the nitrogen-rich Mo_(2)C for modulating the band structure via decomposing the pre-coordination bonded polymer in a pressure-tight tube sealing system.Pre-bonded c/N-Mo in the coordination precursor constructs a micro-confinement space,enabling the homogeneous nitrogenization in-situ happened during the formation of Mo_(2)C.Simultaneously,the evolved gases from the precursor decomposition in tube sealing system establish a macro-confinement environment,preventing the lattice N escape and further endowing a continuous nitridation.Combining the multiscale confinement effects,the nitrogen-rich Mo2C displays as high as 25%N-Mo concentration in carbide lattice,leading to a satisfactory band structure.Accordingly,the constructed nitrogen-rich Mo_(2)C reveals an adorable catalytic activity for HER in both alkaline and acid solution.It is anticipated that the multiscale confinement synthesis strategy presents guideline for the rational design of electrocatalysts and beyond.

Template-Induced Graphitic Nanodomains in Nitrogen-Doped Carbons Enable High-Performance Sodium-Ion Capacitors

Sodium-ion capacitors(SICs)have great potential in energy storage due to their low cost,the abundance of Na,and the potential to deliver high energy and power simultaneously.This article demonstrates a template-assisted method to induce graphitic nanodomains and micro-mesopores into nitrogen-doped carbons.This study elucidates that these graphitic nanodomains are beneficial for Na+storage.The obtained N-doped carbon(As8Mg)electrode achieved a reversible capacity of 254 mA h g^(-1)at 0.1 A g^(-1).Moreover,the As8Mg-based SIC device achieves high combinations of power/energy densities(53 W kg^(-1)at 224 Wh kg^(-1)and 10410 W kg^(-1)at 51 Wh kg^(-1))with outstanding cycle stability(99.7%retention over 600 cycles at 0.2 A g^(-1)).Our findings provide insights into optimizing carbon’s microstructure to boost sodium storage in the pseudocapacitive mode.

Ribosome-inspired electrocatalysts inducing preferential nucleation and growth of three-dimensional lithium sulfide for high-performance lithium-sulfur batteries

Nucleation of lithium sulfide(Li_(2)S)induced by electrocatalysts plays a crucial role in mitigating the shut-tle effect.However,short-chain polysulfides on electrocatalysts surfaces tend to re-dissolve into elec-trolytes,delaying Li_(2)S supersaturation and its nucleation.In this study,we draw inspiration from the ribosome-driven protein synthesis process in cells to prepare ultrasmall nitrogen-doped MoS_(2) nanocrys-tals anchored on porous nitrogen-doped carbon networks(N-MoS_(2)-NC)electrocatalysts.Excitedly,the ex-situ SEM demonstrates that ribosome-inspired N-MoS_(2)-NC electrocatalysts induce early nucleation and rapid growth of three-dimensional Li_(2)s during discharge.Theoretical calculations reveal that the Li-s bond length in N-MoS_(2)-Li_(2)S(100)is shorter,and the corresponding interfacial formation energy is lower than in MoS_(2)-Li_(2)S(100).This accelerated conversion of lithium polysulfides to Li_(2)S can enhance the utilization of active substances and inhibit the shuttle effect.This study highlights the potential of ribosome-inspired N-MoS_(2)-NC in improving the electrochemical stability of Li-S batteries,providing valuable insights for future electrocatalyst design.

Stabilization of cathode electrolyte interphase for aqueous zinc-ion batteries

Aqueous zinc-ion battery systems are attractive for next-generation energy storage devices,however,the unstable electrode electrolyte interphase,especially cathode electrolyte interphase(CEI),has induced rapid capacity attenuation,insufficient cycle life,and severe safety issues.Evolving the researching of CEI formation,composition,dynamic structure,and reaction mechanisms would help in understanding the fundamental electrochemistry at CEI such as electron and ion transport processes,further strengthening the specific capacity,rate,and cycle performance of the cathode materials.In this review,we summarized the latest progress in understanding interfacial reaction mechanisms and ion dynamic behavior,emphasizing the impact of surface-specific adsorption and solvation behaviors on the interface's ultimate structure and chemical composition.Subsequently,the significant challenges that persist in CEI formation mechanisms,such as cathodic dissolution,by-product formation,electrostatic interactions,constrained electrochemical windows,oxygen evolution reaction,overpotentials,phase transitions,and additional factors,were discussed.These challenges are explored to identify triggers contributing to the depletion of active materials and alterations in the composition or state of the CEI.Ultimately,with a deep comprehension of interfacial behaviors,the review articulates innovative optimization strategies through a detailed categorization of approaches in electrolyte engineering,cathode engineering,and artificial CEI development.Furthermore,future challenges and development directions of CEI are presented.We hope to offer insights for constructing robust CEI films to achieve high performance aqueous zinc-ion batteries.

Asymmetric acidic/alkaline N_(2)electrofixation accelerated by high-entropy metal-organic framework derivatives

High-entropy materials are composed of five or more metal elements with equimolar or near-equimolar concentrations within one crystal structure,which offer remarkable structural properties for many applications.Despite previously reported entropy-driven stabilization mechanisms,many high-entropy materials still tend to decompose to produce a variety of derivatives under operating conditions.In this study,we use transition-metal(Ni,Co,Ni,Zn,V)-based high-entropy metal-organic frameworks(HE-MOFs)as the precursors to produce different derivatives under acidic/alkaline treatment.We have shown that HE-MOFs and derivatives have shown favorable kinetics for N_(2)electrofixation in different pH electrolytes,specifically cathodic nitrogen reduction reaction in acidic media and anodic oxygen evolution reaction in alkaline media.To buffer the pH mismatch,we have further constructed an asymmetric acidic/alkaline device prototype by using bipolar membranes.As expected,the prototype showed remarkable activities,with an NH_(3)yield rate of 42.76μg h^(−1)mg^(−1),and Faradaic efficiency of 14.75%and energy efficiency of 2.59%,which are 14.4 and 4.4 times larger than those of its symmetric acidic and alkaline counterparts,respectively.

Band Engineering and Morphology Control of Oxygen‑Incorporated Graphitic Carbon Nitride Porous Nanosheets for Highly Efficient Photocatalytic Hydrogen Evolution

Graphitic carbon nitride(g-C3N4)-based photocatalysts have shown great potential in the splitting of water.However,the intrinsic drawbacks of g-C3N4,such as low surface area,poor diffusion,and charge separation efficiency,remain as the bottleneck to achieve highly efficient hydrogen evolution.Here,a hollow oxygen-incorporated g-C3N4 nanosheet(OCN)with an improved surface area of 148.5 m2 g^−1 is fabricated by the multiple thermal treatments under the N2/O2 atmosphere,wherein the C–O bonds are formed through two ways of physical adsorption and doping.The physical characterization and theoretical calculation indicate that the O-adsorption can promote the generation of defects,leading to the formation of hollow morphology,while the O-doping results in reduced band gap of g-C3N4.The optimized OCN shows an excellent photocatalytic hydrogen evolution activity of 3519.6μmol g^−1 h^−1 for~20 h,which is over four times higher than that of g-C3N4(850.1μmol g^−1 h^−1)and outperforms most of the reported g-C3N4 catalysts.

Precursor-modified strategy to synthesize thin porous amino-rich graphitic carbon nitride with enhanced photocatalytic degradation of RhB and hydrogen evolution performances

The photocatalytic activity of carbon nitride(CN)materials is mainly limited to small specific surface areas,limited solar absorption,and low separation and mobility of photoinduced carriers.In this study,we developed a precursor-modified strategy for the synthesis of graphitic CN with highly efficient photocatalytic performance.The precursor dicyandiamide reformed by different acids undergoes a basic structural change and transforms into diverse new precursors.The thin porous amino-rich HNO_(3)-CN(5H-CN)was calcined by dicyandiamidine nitrate,formed by concentrated nitric acid modified dicyandiamide,and presented the best photocatalytic degradation rate of Rh B,more than 34 times that of bulk graphitic CN.Moreover,the photocatalytic hydrogen evolution rate of 5H-CN significantly improved.The TG-DSC-FTIR analyses indicated that the distinguishing thermal polymerization process of 5H-CN led to its thin porous amino-rich structure,and the theoretical calculations revealed that the negative conduction band potential of 5H-CN was attributed to its amino-rich structure.It is anticipated that the thin porous structure and the negative conduction band position of 5H-CN play important roles in the improvement of the photocatalytic performance.This study demonstrates that precursor modification is a promising project to induce a new thermal polycondensation process for the synthesis of CN with enhanced photocatalytic performance.

Well-dispersed ultrafine nitrogen-doped TiO_2 with polyvinylpyrrolidone(PVP) acted as N-source and stabilizer for water splitting

In this paper, ultrafine nitrogen-doped TiO2 photocatalyst with enhanced photocatalytic water-splitting properties was successfully fabricated via a solvothermal method. Herein, polyvinylpyrrolidone（PVP） was used as both nitrogen source and stabilizer. The enhancement in water-splitting process can be attributed to the doping of element nitrogen, which could supply an intermediate energy level and promote the separation of photo-excited holes and electrons. Moreover, this paper provides a new application of high-molecular polymer to synthesize solar-driven water-splitting photocatalysts.

Tortuosity regulation of two-dimensional nanofluidic films for water evaporation-induced electricity generation

Water evaporation-induced electricity generation is a promising technology for renewable energy harvesting.However,the output power of some reported two-dimensional(2D)nanofluidic films is still restricted by the relatively weak water–solid interactions within the tortuous nanochannels.To further enhance the comprehension and utilization of water–solid interactions,it is of utmost importance to conduct an in-depth investigation and propose a regulatory concept encompassing ion transport.Herein,we propose tortuosity regulation of 2D nanofluidic titanium oxide(Ti_(0.87)O_(2))films to optimize the ion transport within the interlayer nanochannel for enhanced efficiency in water evaporation-induced electricity generation for the first time.The significance of tortuosity in ion transport is elucidated by designing three 2D nanofluidic films with different tortuosity.Tortuosity analysis and in situ Raman measurement demonstrate that low tortuosity can facilitate the formation of efficient pathways for hydrated proton transport and promote water–solid interactions.Consequently,devices fabricated with the optimized 2D nanofluidic films exhibited a significantly enhanced output power density of approximately 204.01μW·cm^(−2),far exceeding those prepared by the high-tortuosity 2D nanofluidic films.This work highlights the significance of the construction of low tortuosity channels for 2D nanofluidic films with excellent performance.

Modularized sulfur storage achieved by 100% space utilization host for high performance lithium-sulfur batteries

Popularization of lithium-sulfur batteries(LSBs) is still hindered by shuttle effect and volume expansion.Herein, a new modularized sulfur storage strategy is proposed to solve above problems and accomplished via employing 100% space utilization host material of cobalt loaded carbon nanoparticles derived from ZIF-67. The modular dispersed storage of sulfur not only greatly increases the proportion of active sulfur,but also inhibits the occurrence of volume expansion. Meanwhile, 100% space utilization host material can greatly improve the conductivity of the cathode, provide a larger electrolyte wetting interface and effectively suppress the shuttle effect. Moreover, loaded cobalt particles have high catalytic activity for electrochemical reaction and can effectively improve the redox kinetics. The cell with new cathode host material carbonized at 650 ℃(ZIF-67(650 ℃)) exhibits superior rate performance and can maintain a high specific capacity of 950 m Ah/g after 100 cycles at 0.2 C, showing a good cycle stability.

Metal-organic frameworks derived low-crystalline NiCo_(2)S_(4)/Co_(3)S_(4) nanocages with dual heterogeneous interfaces for high-performance supercapacitors

Nickel cobalt bimetallic heterogeneous sulfides are attractive battery-type materials for electrochemical energy storage.However,the precise synthesis of electrode materials that integrate highly efficient ions/electrons diffusion with abundant charge transfer channels has always been challenging.Herein,an effective and concise controllable hydrothermal approach is reported for tuning the crystalline and integrated structures of MOF-derived bimetallic sulfides to accelerate the charge transfer kinetics,and thus enabling rich Faradaic redox reaction.The as-obtained low-crystalline heterogeneous NiCo_(2)S_(4)/Co_(3)S_(4)nanocages exhibit a high specific capacity(1023 C/g at 1 A/g),remarkable rate performance(560 C/g at 10A/g),and outstanding cycling stability(89.6%retention after 5000 cycles).Furthermore,hybrid supercapacitors fabricated with NiCo_(2)S_(4)/Co_(3)S_(4)and nitrogen-doped reduced graphene oxide display an outstanding energy density of 40.8 Wh/kg at a power density of 806.3 W/kg,with an excellent capacity retention of 88.3%after 10000 charge-discharge cycles.

Supramolecular assembly-derived carbon-nitrogen-based functional materials for photo/electrochemical applications: progress and challenges

Supramolecular chemistry during the synthesis of carbon-nitrogen-based materials has recently experienced a renaissance in the arena of photocatalysis and electrocatalysis.In this review,we start with the discussion of supramolecular assemblies-derived carbon-nitrogen-based materials’regulation from the aspect of morphology,chemical composition,and micro/nanostructural control.Afterwards the recent advances of these materials in energy and environment related applications,including degradation of pollutants,water splitting,oxygen reduction reactions,CO_(2) reduction reactions along with organic synthesis are summarized.The correlations between the structural features and physicochemical properties of the carbonnitrogen-based materials and the specific catalytic activity are discussed in depth.By highlighting the opportunities and challenges of supramolecular assembly strategies,we attempt an outlook on possible future developments for highly efficient carbon-based photo/electrocatalysts.

Functional inorganic additives in composite solid-state electrolytes for flexible lithium metal batteries

Flexible lithium metal batteries with high capacity and power density have been regarded as the core power resources of wearable electronics.However,the main challenge lies in the limited electrochemical performance of solid-state polymer electrolytes,which hinders further practical applications.Incorporating functional inorganic additives is an effective approach to improve the performance,including increasing ionic conductivity,achieving dendrite inhibiting capability,and improving safety and stability.Herein,this review summarizes the latest developments of functional inorganic additives in composite solid-state electrolytes for flexible metal batteries with special emphasis on their mechanisms,strategies,and cutting-edge applications,in particular,the relationship between them is discussed in detail.Finally,the perspective on future research directions and the key challenges on this topic are outlooked.

Synthesis of CdS multipods from cadmium xanthate in ethylenediamine solution

CdS nanocrystals of various shapes were synthesized by using cadmium ethyldithiocarbonatio （xanthate） as a single precursor under solvothermal condition. The reaction temperature, cadmium concentration, and solvents determine the CdS morphology. Multipodal CdS structures of different fractions of all particles were obtained at temperatures ranging from 100 to 180 ℃ with the corresponding precursor concentrations in ethylenediamine （EDA） solution. This approach is different from that reported in the literature, where EDA is regarded as a solvent favorable to the formation ofCdS nanorods instead of pods. Uniform CdS multipods were prepared at 160 ℃ with 1.0 g of cadmium xanthate. The formation of CdS multipods in EDA solution may be attributed to a synergistic effect between the reaction temperature and Cd concentration, i.e., thermodynamically and kinetically controlled growth of the CdS wurtzite （WZ） and zinc blende （ZB） phases, as confirmed by the structural characterization of the component CdS crys- tals. EDA and xanthate ligands act as co-assisted capping agents in the growth of CdS multipods. When using N,N-dimethylformamide （DMF） and ethylene glycol （EG） as solvents, the CdS appears as triangular particles and flower-like microspheres assembled by polyhedrons, respectively.

A Combinatorial Auction-Based Collaborative Cloud Services Platform

In this paper, we present a novel, dynamic collaboration cloud platform in which a Combinatorial Auction（CA）-based market model enables the platform to run effectively. The platform can facilitate expense reduction and improve the scalability of the cloud, which is divided into three layers： The user-layer receives requests from end-users, the auction-layer matches the requests with the cloud services provided by the Cloud Service Provider（CSP）, and the CSP-layer forms a coalition to improve serving ability to satisfy complex requirements of users.In fact, the aim of the coalition formation is to find suitable partners for a particular CSP. However, identifying a suitable combination of partners to form the coalition is an NP-hard problem. Hence, we propose approximation algorithms for the coalition formation. The Breadth Traversal Algorithm（BTA） and Revised Ant Colony Algorithm（RACA） are proposed to form a coalition when bidding for a single cloud service in the auction. The experimental results show that RACA outperforms the BTA in bid price. Other experiments were conducted to evaluate the impact of the communication cost on coalition formation and to assess the impact of iteration times for the optimal bidding price. In addition, the performance of the market model was compared to the existing CA-based model in terms of economic efficiency.