Search

Vanadium‐based aqueous zinc‐ion batteries (AZIBs) exhibit significant potential for large‐scale energy storage applications, attributed to their inherent safety characteristics. Addressing the slow transport kinetics of divalent Zn2+ within the cathode lattice, thereby enhancing the rate capability and stability, is essential for the Zn‐V battery system. In this study, a local electric field (LEF) strategy is introduced to accelerate the Zn2+ diffusion by creating abundant oxygen vacancies (Ov) in V2O5. Comprehensive characterization and density functional theory (DFT) calculations reveal the formation of the Ov induced atomic‐level donor‐acceptor couple configuration, verify and visualize the LEF. The fabricated LEF‐enhanced vanadium oxide (LEF‐VO) exhibits exceptional rate capability, achieving 338.3 mA h g−1 at a current density of 10 A g−1, and maintaining 66.4% of its capacity over a range from 0.2 to 20 A g−1. Furthermore, the influence of the LEF on expediting Zn2+ diffusion kinetics is elucidated, correlating to the electrical force. This novel LEF approach offers valuable insights for advancing high‐rate cathode materials. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMS) exhibit significant promise as non‐noble‐metal electrocatalysts for the oxygen evolution reaction (OER) in alkaline environments, notwithstanding their susceptibility to long‐term instability due to the gradual leaching of surface‐reconstructed sulfate ions (SO42−). In this study, a sulfate ion‐assisted strategy is proposed to stabilize the surface‐reconstructed SO42− of FeNiS2. The findings reveal that SO42− experiences considerable loss in KOH due to the infinite concentration gradient of SO42− on the surface. Conversely, in K2SO4/KOH, this strategy mitigates rapid leaching and preserves the predominant surface‐reconstructed SO42−, thereby enhancing stability in both accelerated degradation (5000 cycles) and long‐term (≥120 h) tests, with ≈95% current density retained. Furthermore, the optimal concentration of SO42− proves to be crucial, as supported by both experimental and theoretical results. This approach offers insights into bolstering the long‐term OER stability of TMS and similar compounds, thereby advancing the prospects for widespread application in electrocatalytic water splitting. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries (AZIBs), recognized for their safety and environmental friendliness, hold significant promise for large‐scale energy storage. However, the rapid capacity degradation resulting from the dissolution of active cathode materials hampers the advancement of AZIBs. Here, Ru0.2V2O5∙0.41H2O (RuVO) is synthesized with remarkable capacity retention (98.2% over 5000 cycles at 10 A g−1). The pre‐intercalation of Ru3+ enhances the stability of both intrinsic and cycling structures, elevating the Gibbs free energy and suppressing V‐dissolution thermodynamically. Additionally, Ru3+ intercalation modulates the potential energy surface of Zn2+ migration, leading to the dominance of Zn2+ in the insertion/extraction mechanism, thereby kinetically impeding the dissolution reaction. This study elucidates the dissolution thermodynamics and kinetics of V‐based cathodes through a combination of experiments, mechanism analyses, and density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) has attracted significant attention as a water treatment technology owing to its low cost, high efficiency, and eco‐friendliness. However, the unsatisfactory desalination performance of traditional electrode materials hinders the development of CDI. Herein, 1T‐MoS2/C hybrid microspheres are successfully fabricated through confinement and phase engineering strategies. The confinement effect of porous hollow carbon microspheres reduces the overgrowth and agglomeration of MoS2 nanosheets, which is beneficial for exposing more active sites and enhancing stability. Meanwhile, the 1T phase MoS2 displays high intrinsic conductivity and large interlayer spacing, which is conducive to rapid insertion/extraction of Na+. Consequently, 1T‐MoS2/C hybrid becomes a prospect electrode material for CDI, which showcases outstanding desalination capacity (48.1 mg/g at 1.2 V), eminent desalination rate as well as exceptional stability. Moreover, the desalination mechanisms are clarified through various characterizations and density functional theory calculations. This study provides new perspectives on designing high‐performance MoS2‐based CDI electrode materials. [ABSTRACT FROM AUTHOR]

The simultaneous optimization of sluggish reaction kinetics and mass transfer in bifunctional oxygen electrocatalysts for air cathodes remains a great challenge. This study utilizes CoAl‐layered double hydroxide as a metal precursor to fabricate a bifunctional oxygen electrocatalyst, denoted as CoAlOXD‐Thin. This electrocatalyst features a specific core–shell structure of Co species, which grows on an aerophilic and conductive substrate composed of Al2O3 and carbon. It is successfully demonstrated that the thickness of Co@Co3O4 core–shell structure can be easily controlled by selecting different precursors and the combination of Co core and Co3O4 shell optimizes the adsorption strength of intermediates, leading to enhanced catalytic performance. Additionally, the Al species plays a dual role. It not only facilitates the mass transfer of oxygen species but also hinders the 2e− pathway of oxygen reduction reaction, leading to improved selectivity. Notably, the Zn–air batteries utilizing CoAlOXD‐Thin demonstrate an impressive peak power density of 216.2 mW cm−2, a high specific capacity of 800.8 mAh gZn−1, and excellent cycling stability and reversibility, surpassing those of the Pt/C + RuO2 catalyst. This study presents a novel approach to enhance air cathode performance by optimizing reaction kinetics and mass transfer through precursor design. [ABSTRACT FROM AUTHOR]

The practical applications of lithium–sulfur batteries are presently hindered by the shuttle effect, sluggish reaction kinetics, and poor electronic conductivity of sulfur. Siloxene, a new 2D nanomaterial with three types of structures (Weiss, chain like, and Kautsky), is regarded to be a promising cathode‐supporting material for Li–S batteries. Herein, a series of 3d transition metal single‐atom embedded siloxenes (TM‐SA‐siloxenes) is designed and their potential in Li–S batteries is evaluated by first‐principles calculations. It is found that Weiss‐siloxene shows the best polysulfide anchoring ability and lowest Gibbs free energy for the sulfur reduction reaction (SRR). Among a series of TM‐SA‐siloxenes, Co‐SA‐siloxene is identified as the optimal candidate. It shows moderate adsorption energies for polysulfides and outstanding bifunctional electrocatalytic activity for SRR and Li2S decomposition, as well as excellent electronic conductivity. It is also revealed that suitable d and p band center positions, obvious hybridization between Co–3d and S–3p orbitals, and more charge obtained from adsorbed polysulfides, contribute to the high redox kinetics of Co‐SA‐siloxene for the catalyzing conversion of polysulfides. These interesting results provide valuable theoretical guidance for the study of siloxene‐based cathode host materials for Li–S batteries. [ABSTRACT FROM AUTHOR]

Fenton‐like reactions with persulfates as the oxidants have attracted increasing attentions for the remediation of emerging antibiotic pollutions. However, developing effective activators with outstanding activities and long‐term stabilities remains a great challenge in these reactions. Herein, a novel activator is successfully synthesized with single iron atoms anchored on porous N‐doped carbon (Fe‐N‐PC) by a facile chemical vapor deposition (CVD) method. The single Fe atoms are coordinated with four N atoms according to the XANES, and the Fe‐N4‐PC shows enhanced activity for the activation of peroxymonosulfate (PMS) to degrade sulfamethoxazole (SMX). The experiments and density functional theory (DFT) calculations reveal that the introduction of single Fe atoms will regulate the main active sites from graphite N into Fe‐N4, thus could enhance the stability and tune the PMS activation pathway from non‐radical into radical dominated process. In addition, the N atoms connected with single Fe atoms in the Fe‐N4‐C structure can be used to enhance the adsorption of organic molecules on these materials. Therefore, the Fe‐N4‐C here has dual roles for antibiotics adsorption and PMS activation. The CVD synthesized Fe‐N4‐C shows enhanced performance in persulfates based Fenton‐like reactions, thus has great potential in the environmental remediation field. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) is a key reaction for many renewable energy storage and conversion techniques. Developing efficient non‐precious metal‐based electrocatalysts for OER has attracted increasing attention. Herein is reported a strategy to fabricate hierarchical cobalt borate/Ti3C2Tx MXene (Co‐Bi/Ti3C2Tx) hybrid through fast chemical reactions at room temperature. This interesting hierarchical structure of Co‐Bi/Ti3C2Tx hybrid is beneficial for exposing more active sites, improving mass diffusion, and charge‐transfer pathways for electrochemical reaction. Moreover, a strong interaction between Co‐Bi and Ti3C2Tx ensures efficient charge transfer and facilitates the electrostatic attraction of more anionic intermediates for a fast redox process. Consequently, the hierarchical Co‐Bi/Ti3C2Tx hybrid shows extraordinary OER catalytic activity to deliver a current density of 10 mA cm−2 at an overpotential of 250 mV, and a Tafel slope of about 53 mV dec−1. Pushing to the edge: Two‐dimensional Ti3C2Tx supported cobalt borate (Co‐Bi) is a potential catalyst for oxygen evolution reaction in alkaline medium. The Co‐Bi/Ti3C2Tx hybrid displays a hierarchical structure enabling improved exposure of active surface sites, mass diffusion, and charge‐transfer characteristics. Consequently, the hybrid material can deliver a stable current density (10 mA cm−2) at a low overpotential (250 mV). [ABSTRACT FROM AUTHOR]

Abstract: MXenes, a family of two‐dimensional transition‐metal carbide and nitride materials, are thought to be promising materials in energy storage because of their high electronic conductivity, hydrophilic surfaces, and low diffusion barriers. MXenes are generally prepared by removing the “A” elements (A=Al, Si, Sn, etc.) from their corresponding MAX phases by using hydrofluoric acid (HF) and other etching agents, although these “A” elements usually have great volumetric and gravimetric capacities. In a study of the etching progress of Ti3AlC2 and evaluation of their anode performance in lithium‐ion batteries, a partially etched sample (0.5 h‐pe Ti3C2Tx) is found to have much higher capacity (160 mAh g−1, 331.6 mAh cm−3 at 1C) when compared with the fully etched Ti3C2Tx (110 mAh g−1, 190.3 mAh cm−3 at 1C). Moreover, a 99 % capacity retention was observed even after 1000 cycles in the 0.5 h‐pe Ti3C2Tx anode. This interesting result can be explained, at least in part, by the alloying of the residual Al during lithiation. [ABSTRACT FROM AUTHOR]

Abstract: Porous organic polymers (POPs) are promising precursors for developing high performance transition metal–nitrogen–carbon (M/N/C) catalysts for the oxygen reduction reaction (ORR). The rational design of POP precursors remain a great challenge, because of the elusive structural association between the sacrificial POPs and the final M/N/C catalysts. Based on covalent triazine frameworks (CTFs), we developed a series of S‐doped Fe/N/C catalysts by selecting six different aromatic nitriles as building blocks. A new mixed solvent of molten FeCl3 and S was used for CTF polymerization, which benefited the formation of Fe–Nx sites and made the subsequent pyrolysis process more convenient. Comprehensive study of these CTF‐derived catalysts showed that their ORR activities are not directly dependent on the theoretical N/C ratio of the building block, but closely correlated to the ratio of the nitrile group to benzene ring (Nnitrile/Nbenzene) and geometries of the building blocks. The high ratios of Nnitrile/Nbenzene are crucial for ORR activity of the final catalysts owing to the formation of more N‐doped micropores and Fe–Nx sites in pyrolysis possess. The optimized catalyst shows high ORR performances in acid and superior ORR activity to the Pt/C catalysts under alkaline conditions. [ABSTRACT FROM AUTHOR]

Abstract: The oxygen reduction reaction (ORR) is an important process in energy conversion and storage devices. Great efforts have been focused on developing efficient, durable, and low‐cost non‐Pt catalysts. In this study, a novel hybrid ORR catalyst of Co3O4 and covalent triazine framework (CTF) was prepared through the in‐situ growth of Co3O4 nanoparticles on CTF by using a hydrothermal method. Systematical studies revealed that this hybrid catalyst not only has a synergistic catalytic effect in the ORR, but also has superior stability and better methanol resistance than commercial Pt/C catalysts. [ABSTRACT FROM AUTHOR]

A Cu2O/g-C3N4/WS2 triple-layer photocathode was fabricated by using a layer-by-layer assembly method for photoelectrochemical hydrogen evolution. Cu2O was electrodeposited on the FTO as the active layer for light harvesting. The chemically inert g-C3N4 can protect the unstable Cu2O layer and form a p-n junction with Cu2O to increase the light-to-electricity conversion efficiency. Mixed-phase WS2 nanosheets were obtained through a lithium insertion method and used as an effective hydrogen evolution catalyst for photocurrent-to-hydrogen conversion. This photocathode is effective for photoelectrochemical hydrogen evolution, and a photocurrent of −9.5 mA cm−2 at −0.55 V versus RHE (pH 6.0) can be obtained under visible light ( λ≥420 nm, 100 mW cm−2). [ABSTRACT FROM AUTHOR]

Aqueous zinc‐selenium (Zn‐Se) batteries have garnered much attention due to their inherent safety and high specific capacity. Unfortunately, the problem of sluggish redox reaction represents a significant obstacle to the development of aqueous Zn‐Se batteries. Here, a nitrogen‐phosphorus asymmetrically coordinated copper single atom catalytic host material (CuN3P1@C) is synthesized for an aqueous Zn‐Se battery. The CuN3P1@C host material exhibits a rich porous structure, high‐loading of Cu single atoms, and unique asymmetric coordination environment, which significantly reduces the reaction energy barrier for the redox reaction between Se and Zn, enhancing the electrochemical performance of the aqueous Zn‐Se battery. Consequently, the Se/CuN3P1@C cathode achieves a high specific capacity of 756 mAh g−1 at 0.2 A g−1 and cycling stability of 4 000 cycles at 5.0 A g−1 (capacity decay of 0.0044% per cycle). Meanwhile, the conversion mechanism of an aqueous Zn‐Se battery is systematically explored via systematical characteristics and density functional theory calculations. This work opens up a novel approach to boosting the redox reaction of aqueous Zn‐Se batteries by modulating single atom‐based host materials via heteroatoms. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction reaction (NO3RR) can convert nitrate contaminants into ammonia with higher added value. However, due to the NO3RR involving complex multi‐electron reactions, there is an urgent need to develop efficient electrocatalysts. Herein, CoCu Janus nanoparticles loaded on Ti3C2Tx MXene (CoCu‐Ti3C2Tx) is synthesized via the combination of molten salt etching and galvanic replacement strategy. The tandem catalysis of CoCu Janus NPs can maintain the balance between nitrogenous intermediates and active hydrogen (Hads). CoCu‐Ti3C2Tx exhibits a high NH3 yield of 8.08 mg h−1 mgcat.−1 and a satisfactory Faradaic efficiency of 93.6% at −0.7 V versus reversible hydrogen electrode (RHE). The Zn‐NO3− battery assembled with CoCu‐Ti3C2Tx shows an excellent power density of 10.33 mW cm−2, an NH3 yield of 1.52 mg h−1 mgcat.−1 and a Faradaic efficiency of 95.3% at 10 mA cm−2, which enables the simultaneous elimination of nitrate pollutants, ammonia production, and energy supply. Moreover, a series of verification experiments and density functional theory calculation are combined to reveal the reaction path and tandem catalytic mechanism. This work not only provides a new inspiration for the design of tandem catalysts but also promotes the development of Zn‐nitrate battery. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) on 2D nanomaterials have great potential as efficient and low‐cost electrocatalysts for clean energy technologies. The coordination environments, as well as the physicochemical properties of the 2D supports, play key roles in tuning the catalytic activity and reaction mechanism of the single‐atom centers. This review first summarizes the suitable synthetic strategies of single‐atom on different 2D supports. The methods that facilitate the formation of relative homogeneous structure and enable the regulation of the surrounding atomic environment of metal center are discussed. Furthermore, the recent progress of SACs for energy‐related electrochemical applications is reviewed, including oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, CO2 reduction reaction, and nitrogen reduction reaction. The strategies about modulation of the electronic structure of single‐atom for enhanced performance are highlighted, together with a discussion of the current issues and the prospects of this field. [ABSTRACT FROM AUTHOR]

Herein, a novel 3D free‐standing electrode is synthesized, consisting of Ni3S2 supported on a Ni foam (NF) with a graphite foam (GF) intercalated between them (Ni3S2@GF@NF). The hydrothermally synthesized Ni3S2 has a hierarchical structure with abundant active sites exposed, and intimate interfacial contact can be formed during the in situ synthesis process. Moreover, the intercalated GF has a large surface area and good electric conductivity, which can create a new short route to facilitate electron transfer onto the active surface of Ni3S2. The Ni3S2@GF@NF electrode exhibits an excellent hydrogen evolution reaction performance with an early overpotential of 99 mV vs reversible hydrogen electrode at 10 mA cm−2 and a small Tafel slope of 98.2 mV dec−1 in alkaline solutions. However, the overpotential at 10 mA cm−2 and Tafel slope for the oxygen evolution reaction are 240 mV and 62.4 mV dec−1 in alkaline solutions. Using Ni3S2@GF@NF as both anode and cathode, only a small cell voltage of 1.63 V is needed to obtain 10 mA cm−2 for overall water splitting, comparable with the best free‐standing materials. Moreover, it exhibits a good stability due to the protection of GF. The free‐standing Ni3S2@GF@NF electrode contains no noble metals and should have a great potential in electrochemical water splitting. [ABSTRACT FROM AUTHOR]