EcoEnergy最新文献

Ni-rich cathodes are more promising candidates to the increasing demand for high capacity and the ability to operate at high voltages. However, the high Ni content creates a trade-off between energy density and cycling stability, mainly caused by the chemo-mechanical degradation. Oxygen evolution, cation mixing, rock salt formation, phase transition, and crack formation contribute to the degradation process. To overcome this problem, strategies such as doping, surface coating, and core-shell structures have been employed. The advantage of doping is to engineer the cathode surface, structure, and particle morphology simultaneously. This review aims to summarize recent advances in understanding chemo-mechanical degradation mechanism and the role of different dopants in enhancing the thermal stability and overall electrochemical performance. The pinning and pillaring effects of dopants on suppressing oxygen evolution, cation mixing, and phase transition are introduced. It is found that the higher ionic radii enable dopants to reside on cathode particles, preserving the particle surface and refining particle morphology to suppress crack formation. Finally, the effect of doping on Li ion diffusion, rate capability, and long-term stability are discussed.

The development of noble-metal free electrocatalysts with low production cost is of utmost importance for sustainable water electrolysis. Herein, we present a fast flexible synthesis pathway for the preparation of a variety of different medium- and high-entropy spinel sulfides of various compositions, using a non-aqueous microwave-assisted synthesis without any H₂S. Nanoparticulate high-entropy sulfides containing up to 8 different metal cations can be obtained after an extremely short synthesis time of only 1 min and comparatively low temperatures of 200–230°C. We further demonstrate the high activity of the obtained sulfides for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER).

To achieve efficient and stable hydrogen production while addressing the corrosive effects of seawater on electrodes, integrating the energy-saving urea oxidation reaction (UOR) with the hydrogen evolution reaction (HER) presents a promising low-energy solution. However, developing low-cost, high-performance bifunctional electrocatalysts for both HER and UOR remains a significant challenge. In this work, we prepared bifunctional electrocatalysts featuring Mn_xNi_2−xP nanoflower structures grown on nickel foam using a simple hydrothermal phosphatization method. These catalysts demonstrated excellent performance in alkaline freshwater and seawater, with notably low overpotentials of 251 and 257 mV for HER, and 1.33 and 1.37 V for UOR. Combining its bifunctional activity in UOR and HER in a two-electrode system, an energy saving of 0.19 V potential compared to water electrolysis through water oxidation can be acquired to reach 100 mA cm⁻² current density. Moreover, the catalyst also maintains fairly stable after long-term testing, indicating its potential for efficient and energy-saving hydrogen production. Our study reveals that the synergistic interaction between Ni and Mn metals enhances the electronic structure of the electrocatalysts, significantly boosting both UOR and HER activities. Additionally, Mn doping alters the morphological structure, creating nanoflowers with abundant active sites, while nickel-iron phosphides improve the catalyst's corrosion resistance in seawater. This work provides valuable insights into the design of low-cost, stable non-precious metal electrocatalysts for seawater and freshwater splitting, combining hydrogen evolution with urea-assisted energy-saving.

Developing high-efficiency and environmentally-friendly thermoelectric materials has been a significant challenge. Conventional thermometric materials consist of heavy (toxic) elements to reduce thermal conductivity (κ), while we demonstrated light-element hydride anion (H⁻) substitution in SrTiO₃ can largely reduce κ and enhance thermometric efficiency (ZT) without heavy elements. In this paper, we succeeded in maximizing the ZT of SrTiO_3−xH_x by applying topochemical reaction directly to SrTiO₃ epitaxial films with CaH₂, which realized wide-range control of carrier concentration (n_e) from 1.5 × 10²⁰ cm⁻³ to 4.1 × 10²¹ cm⁻³. The power factor (PF) showed a dome-shaped behavior with respect to n_e, and the maximum PF = 22.5 μW/(cmK²) was obtained at the optimal n_e = 3.4 × 10²⁰ cm⁻³. Carrier transport analyses clarified that the carrier mobility was limited by impurity scattering of H-related impurities in the SrTiO_3−xH_x films, while the hydrogen substitution induced a much lower κ of 4.6 W/(mK) than other heavy-element substituted Sr_1−xLa_xTiO₃ and SrTi_1−xNb_xO₃ films in the wide n_e range, resulting in the higher ZT value of 0.14 in maximum at room temperature. In addition, the ZT increased to 0.17 at 373 K due to the large decrease in κ for a SrTiO_3−xH_x film with the hydrogen concentration of 1.2 × 10²¹ cm⁻³. Further study on H⁻ substitution approach and modulation of the H state in transition metal oxides would lead to development of high ZT environmentally-friendly thermoelectric materials.

Surface and interfacial chemistry play a vital role in shaping the properties of two-dimensional transition metal carbides and nitrides (MXenes). This study focuses on utilizing Lewis-basic halides (LiCl/KCl) for thermal treatment of multilayered Ti₃C₂T_x, leading to the simultaneous modulation of interlayer spacing and surface functional groups. Compared to the pristine Ti₃C₂T_x, the LiCl/KCl treated sample (heating temperature: 450°C, denoted as LK-Ti₃C₂T_x-450) showcases a remarkable increase in the interlayer spacing and synergistic optimization of the functional groups. These modifications endow LK-Ti₃C₂T_x-450 with enhanced electrochemical properties, rendering it as a promising anode candidate for lithium-ion batteries. The increased interlayer spacing is particularly advantageous, as it facilitates efficient and rapid Li⁺ diffusion, a vital factor in enhancing the performance of energy storage devices.

One of the most promising electrochemical energy storage technologies, aqueous zinc ion batteries (AZIBs), is garnering increasing attention due to their inherent safety, high sustainability, and low cost. However, the challenges posed by dendrite formation and side reactions resulting from uneven deposition of zinc metal anodes significantly impede the reversibility and cycling stability of AZIBs. Given the influence of crystallographic anisotropy on the diversity of deposited metal morphology and crystal orientation, a thorough understanding of the intrinsic texture of zinc is crucial in achieving a dendrite-free zinc anode. This review highlights groundbreaking efforts and significant advancements in promoting the orientational electrodeposition of zinc, encompassing fundamental crystallographic and electrocrystallization theories as well as approaches for achieving textured zinc electrodeposition. The goal is to provide a comprehensive understanding of the crystallography, electrochemistry, and induction mechanisms involved in controlling sustainable zinc orientational electrodeposition for AZIBs. Lastly, four critical research aspects are proposed to facilitate the commercialization of reliable AZIBs.

Perovskite solar cells are promising candidates for low-cost and efficient photovoltaic markets, but their efficiency is usually limited by the non-radiative recombination losses at the mismatched interface of perovskite and transport layers. Herein, we show that the band edges of perovskite thin films can be on-demand engineered by a series of carboxylic-based self-assembled monolayers. Experimental and theoretical studies indicate that the functionalized perovskite inherits the polarity of the monolayer with linear dependence of work function on the molecular dipole moments, which enables the management of interfacial charge transport process. Solar cells with 4-bromophenylacetic acid SAMs achieve about 6.48% enhancement in power conversion efficiency with the champion values over 23%.

Recent years have witnessed a surge in research on aqueous zinc-ion batteries (AZIBs) due to their low cost, stability, and exceptional electrochemical performance, among other advantages. However, practical manufacturing and deployment of AZIBs have been hindered by challenges such as low energy density, significant precipitation-related side reactions, slow ion migration, and dendritic growth. Addressing these issues and enhancing the practical application of AZIBs necessitates the development of novel materials. Carbon dots (CDs), with their distinctive structure and superior electrochemical properties, represent an innovative class of carbon-based materials with broad potential applications for optimizing AZIBs' performance. This study offers a comprehensive review of how CDs can address the aforementioned challenges of AZIBs. It begins with an overview of AZIBs composition and mechanism before delving into the classification, preparation techniques, and functionalization strategies of CDs. The review also thoroughly summarizes the sophisticated roles of CDs as modifiers in electrolytes and electrodes, both positive and negative, and briefly discusses their potential application in membranes. Additionally, it provides a summary of current issues and difficulties encountered in utilizing CDs in AZIBs. This review aims to provide insights and guidance for designing and manufacturing the next generation of high-performance AZIBs.

Photovoltaic–electrolysis (PV-EC) system currently exhibits the highest solar to hydrogen conversion efficiency (STH) among various technical routes. This perspective shifts the focus from the materials exploration in photovoltaics and electrolysis to the critical aspect of thermal management in a PV-EC system. Initially, the theoretical basis that elucidates the relationships between temperature and the performance of both photovoltaics and electrolyzers are presented. Following that, the impact of thermal management on the performance of PV-EC for solar hydrogen production is experimentally demonstrated by designing variables-controlling experiments. It is observed that while utilizing identical PV and EC cells under varying thermal conditions, the highest STH can reach 22.20%, whilst the lowest is only 15.61%. This variation underscores the significance of thermal management in optimizing PV-EC systems. Finally, increased efforts to enhancing heat transfer and optimizing heat distribution are proposed, thus facilitating the design of more efficient PV-EC systems with minimized thermal energy losses.

The sodium hexafluorophosphate (NaPF₆)/carbonate solution is considered as the benchmark electrolyte for sodium-ion batteries (SIBs). However, this NaPF₆ electrolyte undergoes hydrolysis and produces acidic compounds, which deteriorate the electrolyte quality, corrode electrodes, jeopardize electrode interphases, and eventually degrade battery performance. Herein, we introduce tris(trimethylsilyl) phosphate (TMSP) as a multifunctional additive to the carbonate electrolyte. We found that 10% TMSP could effectively remove H₂O molecules and inhibit NaPF₆ hydrolysis, thus improving the electrolyte stability against moisture during the long-term storage. Furthermore, the unique structure of TMSP promotes the formation of thinner, more uniform, and inorganic-rich interphases on the Na₃V₂(PO₄)₃ (NVP) cathode and hard carbon (HC) anode. Consequently, the NVP cathode, HC anode, and full cells demonstrate excellent cycling performance. This work suggests that tailoring the electrolyte formulation can provide multiple benefits for boosting SIB performances, such as stabilizing the electrolyte and regulating the electrolyte/electrode interphase, thereby promoting long-term cycling in sodium-ion batteries.