EcoMat最新文献

The Oxygen evolution reaction (OER) is a pivotal technology driving next-generation sustainable energy conversion and storage devices. Establishing a robust analytical methodology is paramount to fostering innovation in this field. This review offers a comprehensive discussion on measurement and interpretation, advocating for standardized protocols and best practices to mitigate the myriad factors that complicate analysis. The initial focus is directed toward substrate electrodes and gas bubbles, both significant contributors to reduced reliability and reproducibility. Subsequently, the review focuses on intrinsic activity assessment, identification of electrochemical active sites, and the disentanglement of competing process contributions. These careful methodologies ensure the systematic delivery of insights crucial for assessing OER performance. In conclusion, the review highlights the critical role played by precise measurement techniques and unbiased activity comparison methodologies in propelling advancements in OER catalyst development.

The most feasible technique for producing green hydrogen is water electrolysis. In recent years, there has been significant study conducted on the use of transition metal compounds as electrocatalysts for both anodes and cathodes. Peoples have attempted several strategies to improve the electrocatalytic activity of their original structure. One such technique involves introducing rare earth metals or creating heterostructures with compounds based on rare earth metals. The incorporation of rare earth metals significantly enhances the activity by many folds, while their compounds offer structural stability and the ability to manipulate the electronic properties of the original system. These factors have led to a recent boom in investigations on rare earth metal-based electrocatalysts. There is currently a pressing demand for a review article that can provide a comprehensive overview of the scientific advancements and elucidate the mechanistic aspects of the impact of lanthanide doping. This review begins by explaining the electronic structure of the lanthanides. We next examine the mechanistic aspects, followed by recent advancements in lanthanide doping and heterostructure formation for water electrolysis applications. It is expected that this particular effort will benefit a broad audience and stimulate more research in this area of interest.

Double transition metal (DTM) MXenes are a recently discovered class of two-dimensional composite nanomaterials with excellent potential in energy storage applications. Since their emergence in 2015, DTM MXenes have expanded their composition boundary beyond traditional single-metal carbide and nitride MXenes. DTM MXenes offer tunable structures and properties through variations in the constituent transition metals and positioning within the layered lattice. These MXenes can exist in two primary forms: ordered DTMs and solid solutions. The compositional versatility of DTM MXenes offers opportunities to enhance their performance in electrochemical energy storage applications. However, the quality, stability, and surface chemistry of DTM MXenes are influenced by several factors, including the etching process, etchant type, and synthesis route. Currently, limited literature is available on experimentally synthesized DTM MXenes, with most studies focusing on carbide-based MXenes. Most of the articles have dedicated their efforts only to generalized synthesis strategies. Although extensive theoretical studies have explored the suitability of etchants, synthesis parameters, and methods for producing high-quality MXene with selective terminal functional groups, their stability issues have not been thoroughly examined. This review addresses various types of DTM MXenes, their synthesis techniques, and the impact of these methods on their physicochemical properties and electrochemical performance. Additionally, it provides a critical analysis of the causes of instability in MXenes, particularly DTMs, from synthesis to application. The challenges associated with these materials are discussed, along with opportunities and prospects for enhancing synthesis, structural tuning, surface modification, and applications in electrochemical energy storage.

The sulfur utilization efficiency of lithium–sulfur batteries is often limited by the uncontrolled electrodeposition of the insulating Li₂S and the resulting electrode passivation. Herein, purposeful electrode and electrolyte design is used to realize site-selective three-dimensional (3D) Li₂S electrodeposition and thus mitigate the above problem. Site-selective Li₂S nucleation is induced at the tips of CoP nanoneedles grown on a carbon cloth electrode, and the 3D growth of Li₂S at these tips without the passivation of the inner part is achieved using a LiBr-containing high-donor-number electrolyte. The controlled Li₂S morphology is rationalized by considering the tip effect, the energy of Li₂S binding on the electrode surface, and the solubility of Li₂S in the electrolyte. Owing to the suppressed electrode passivation, CoP nanoneedle–decorated carbon cloth electrode and LiBr-containing electrolyte deliver a capacity of >1400 mAh g_s⁻¹ at a current density of 0.33 A g_s⁻¹. Thus, this work paves the way for the active control of Li₂S morphology for high-performance lithium–sulfur batteries.

Rechargeable aqueous zinc (Zn) ion batteries (AZIBs) are gaining popularity in large-scale energy storage due to their low cost, high safety, and environmental friendliness; however, dendrite growth and side reactions in Zn metal anodes limit their practical applications. Additionally, the difficulty of developing successful passivation of Zn anodes, combined with large-area coating of protective layers, remains a major limitation to the commercialization of AZIBs. Here, we introduce two-dimensional (2D) nanomaterials including MoS₂, h-BN, and Ti₃C₂T_x MXene as protective layers for Zn anodes, created on a Zn surface using a scalable, large-area spray-coating process. Examinations of electrochemical performance-related material characterizations revealed that a specific type of 2D material with an optimal thickness prevents vertical growth of Zn dendrites, as well as side reactions including hydrogen evolution and corrosion, resulting in stable device operation with minimal overpotential and extended life, even under harsh measurement conditions. The highly stable MoS₂@Zn anode allowed the MoS₂@Zn//MnO₂ full cell to achieve significantly more stable capacity retention, compared with the bare Zn//MnO₂ cell. Our versatile and scalable solution-based coating technique for easily forming large-area 2D protective layers on Zn anodes offers new insights concerning improvements to AZIB reliability and performance.

Lithium-ion composite solid electrolyte membranes embedded with Li_1.3Al_0.3Ti_1.7P₃O₁₂ and poly(vinylidene fluoride) are prepared using a facile casting method. Furthermore, we added LiI as an active agent for decomposing the anode product. The synergy resulted in a high conductivity of 7.4 mS·cm⁻¹ and lithium-ion mobility of 0.59 and a reduction of the overpotential to 0.86 V for lithium–oxygen batteries (LOBs). The membrane has enhanced Young's modulus of 6.6 GPa that effectively blocked the lithium dendrite growth during the battery operation and puncturing to the membrane led to a significant LOB cycle life of 542 cycles. Meanwhile, Li|Li symmetrical battery overpotential maintained at 42 mV after 470 h of operation.

In order to cope with the increasingly serious problem of energy shortage, supercapacitors have been developed as a clean and renewable energy source, and the supercapacitors with excellent energy density and long cycle life are imperative. Here, by employing a facile liquid–liquid (L-L) interfacial method at room temperature (RT), a set of two-dimensional (2D) metal complex nanosheets N1-N3 have been synthesized by the facile coordination between Co²⁺ ion and 2,3,6,7,10,11-hexaiminotriphenylene (HITP). Given the layered superstructure with well-ordered nanopores, the N1-N3 electrodes displayed excellent capacities of 4751.9, 5770.9 and 6075.2 F g⁻¹ at 1 A g⁻¹, and a good cyclic stability with 92.1% capacity retention after 1000 cycles for the N3 electrode. The asymmetric supercapacitor device with N3 as the positive electrode delivers a maximum energy density of 238.2 Wh kg⁻¹ at a power density of 1610.1 W kg⁻¹ and an excellent cycling stability with a capacitance retention of 109.1% after 5000 cycles. This is the best electroactive bottom-up metal complex nanosheet reported so far for use in supercapacitor, which greatly expands the applicability of this 2D nanomaterial in energy device applications.

MoS₂ as a typical layered transition metal dichalcogenide (LTMD) has attracted considerable attention to work as sodium host materials for sodium-ion batteries (SIBs). However, it suffers from low semiconducting behavior and high Na⁺ diffusion barriers. Herein, intercalation of N-doped amorphous carbon (NAC) into each interlayer of the tiny MoS₂ nanosheets embedded on rGO conductive network is achieved, resulting in formation of rGO@MoS₂/NAC hierarchy with interoverlapped MoS₂/NAC superlattices for high-performance SIBs. Attributed to intercalation of NAC, the resulting MoS₂/NAC superlattices with wide MoS₂ interlayer of 1.02 nm facilitates rapid Na⁺ insertion/extraction and accelerates reaction kinetics. Theoretical calculations uncover that the MoS₂/NAC superlattices are beneficial for enhanced electron transport, decreased Na⁺ diffusion barrier and improved Na⁺ adsorption energy. The rGO@MoS₂/NAC anode presents significantly improved high-rate capabilities of 228, 207, and 166 mAh g⁻¹ at 20, 30, and 50 A g⁻¹, respectively, compared with two control samples of pristine MoS₂ and MoS₂/NAC counterparts. Excellent long-term cyclability over 10 000 cycles with extremely low capacity decay is demonstrated at high current densities of 20 and 50 A g⁻¹. Sodium-ion full cells based on the rGO@MoS₂/NAC anode are also demonstrated, yielding decent cycling stability of 200 cycles at 5C. Our work provides a novel interlayer strategy to regulate electron/Na⁺ transport for fast-charging SIBs.

Developing efficient electrocatalysts with low-cost for the urea oxidation reaction (UOR) is a significant challenge in energy-saving H₂ production owing to its lower thermodynamic potential. Heteroatom incorporation strategy has been proven to boost electrocatalytic activity by altering electronic structures and revealing more active sites on catalysts. Herein, nickel hydroxide nanosheets with various vanadium incorporation (V_x-Ni(OH)₂) were developed through a facile hydrothermal approach. By optimizing the incorporated vanadium contents, V₆-Ni(OH)₂ catalyst exhibited easily accessible active sites and enhanced charge transfer with structural advantages, then assembled as the working electrode for urea-assisted H₂ production. Consequently, V₆-Ni(OH)₂ catalyst demonstrated superior UOR activity compared with other incorporated samples with an overpotential of 1.33 V and a Tafel slope of 28.3 mV dec⁻¹. Theoretical calculations revealed that the improved UOR activity was attributed to the potential determining step of V-Ni(OH)₂, which exhibited lower energy in comparison with the pristine Ni(OH)₂ and increased electronic states density near the Fermi level. Both experimental and theoretical calculations confirmed vanadium incorporation on Ni(OH)₂ could modify the electronic structure of Ni(III) species, improving electrical conductivity, and optimizing the adsorption energy for key reaction intermediates. Furthermore, the crucial contribution of vanadium incorporation with optimized electronic structures to the high UOR activity of Ni(OH)₂ is demonstrated.

Three-dimensional (3D) current collectors (CCs) have emerged as an effective strategy to inhibit dendrites and ensure the safety of lithium (Li) metal anodes. However, existing 3D CCs are generally too heavy (typically tens of mg cm⁻²) or too thick (tens to hundreds of micrometers), making large-scale production and further application challenging. Additionally, the use of single-component 3D CCs, whether electrically active or inert, only exhibits limited effects on stabilizing Li anodes. Here, we present a scalable screen-printing technique for the synthesis of ultralight (~0.4 mg cm⁻²) and ultrathin (~0.54 μm) SiO₂ grids on Cu foil to regulate both the vertical electric field and Li-ion concentration by forming an electrically active/inert dual-function architecture. This technology breaks the limitations of traditional 3D CCs in material/fabrication costs, weight, thickness and especially, scalability for large-scale fabrication. By using this dual-function architecture, our Cu@SiO₂-grid CCs (~8.31 mg cm⁻²), which are even lighter than the original Cu-foil CCs (~8.85 mg cm⁻²), realize an ultra-smooth anode surface without Li dendrites, and thus leads to an ultra-long cyclic life of over 1500 h at 1 mA cm⁻². The assembled Li metal batteries demonstrate excellent capacity retention of ~80% over 400 cycles at 1 C and ~ 76% over 250 cycles at 5 C, which highlight the promising 3D CCs for practical applications.