能源化学最新文献

The balance between cationic redox and oxygen redox in layer-structured cathode materials is an important issue for sodium batteries to obtain high energy density and considerable cycle stability. Oxygen redox can contribute extra capacity to increase energy density, but results in lattice instability and capacity fading caused by lattice oxygen gliding and oxygen release. In this work, reversible Mn²⁺/Mn⁴⁺ redox is realized in a P3-Na_0.65Li_0.2Co_0.05Mn_0.75O₂ cathode material with high specific capacity and structure stability via Co substitution. The contribution of oxygen redox is suppressed significantly by reversible Mn²⁺/Mn⁴⁺ redox without sacrificing capacity, thus reducing lattice oxygen release and improving the structure stability. Synchrotron X-ray techniques reveal that P3 phase is well maintained in a wide voltage window of 1.5–4.5 V vs. Na⁺/Na even at 10 C and after long-term cycling. It is disclosed that charge compensation from Co/Mn-ions contributes to the voltage region below 4.2 V and O-ions contribute to the whole voltage range. The synergistic contributions of Mn²⁺/Mn⁴⁺, Co²⁺/Co³⁺, and O²⁻/(O_n)²⁻ redox in P3-Na_0.65Li_0.2Co_0.05Mn_0.75O₂ lead to a high reversible capacity of 215.0 mA h g⁻¹ at 0.1 C with considerable cycle stability. The strategy opens up new opportunities for the design of high capacity cathode materials for rechargeable batteries.

Transition metal phosphides (TMPs) have been regarded as alternative hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalysts owing to their comparable activity to those of noble metal-based catalysts. TMPs have been produced in various morphologies, including hollow and porous nanostructures, which are features deemed desirable for electrocatalytic materials. Templated synthesis routes are often responsible for such morphologies. This paper reviews the latest advances and existing challenges in the synthesis of TMP-based OER and HER catalysts through templated methods. A comprehensive review of the structure–property–performance of TMP-based HER and OER catalysts prepared using different templates is presented. The discussion proceeds according to application, first by HER and further divided among the types of templates used—from hard templates, sacrificial templates, and soft templates to the emerging dynamic hydrogen bubble template. OER catalysts are then reviewed and grouped according to their morphology. Finally, prospective research directions for the synthesis of hollow and porous TMP-based catalysts, such as improvements on both activity and stability of TMPs, design of environmentally benign templates and processes, and analysis of the reaction mechanism through advanced material characterization techniques and theoretical calculations, are suggested.

BiVO₄ (BVO) is a promising material as the photoanode for use in photoelectrochemical applications. However, the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical performance. To address this, various modifications have been attempted, including the use of ferroelectric materials. Ferroelectric materials can form a permanent polarization within the layer, enhancing the separation and transport of photo-excited electron-hole pairs. In this study, we propose a novel approach by depositing an epitaxial BiFeO₃ (BFO) thin film underneath the BVO thin film (BVO/BFO) to harness the ferroelectric property of BFO. The self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge recombination. As a result, the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density (0.65 mA cm⁻²) at 1.23 V_RHE under the illumination compared to the bare BVO photoanodes (0.18 mA cm⁻²), which is consistent with the increase of the applied bias photon-to-current conversion efficiencies (ABPE) and the result of electrochemical impedance spectroscopy (EIS) analysis. These results can be attributed to the self-polarization exhibited by the inserted BFO thin film, which promoted the charge separation and transfer efficiency of the BVO photoanodes.

Smart wearable devices are regarded to be the next prevailing technology product after smartphones and smart homes, and thus there has recently been rapid development in flexible electronic energy storage devices. Among them, flexible solid-state zinc-air batteries have received widespread attention because of their high energy density, good safety, and stability. Efficient bifunctional oxygen electrocatalysts are the primary consideration in the development of flexible solid-state zinc-air batteries, and self-supported air cathodes are strong candidates because of their advantages including simplified fabrication process, reduced interfacial resistance, accelerated electron transfer, and good flexibility. This review outlines the research progress in the design and construction of nanoarray bifunctional oxygen electrocatalysts. Starting from the configuration and basic principles of zinc-air batteries and the strategies for the design of bifunctional oxygen electrocatalysts, a detailed discussion of self-supported air cathodes on carbon and metal substrates and their uses in flexible zinc-air batteries will follow. Finally, the challenges and opportunities in the development of flexible zinc-air batteries will be discussed.

Rechargeable magnesium batteries (RMBs) hold promise for offering higher volumetric energy density and safety features, attracting increasing research interest as the next post lithium-ion batteries. Developing high performance cathode material by inducing multi-electron reaction process as well as maintaining structural stability is the key to the development and application of RMBs. Herein, multi-electron reaction occurred in VS₄ by simple W doping strategy. W doping induces valence of partial V as V²⁺ and V³⁺ in VS₄ structure, and then stimulates electrochemical reaction involving multi-electrons in 0.5% W-V-S. The flower-like microsphere morphology as well as rich S vacancies is also modulated by W doping to neutralize structure change in such multi-electron reaction process. The fabricated 0.5% W-V-S delivers higher specific capacity (149.3 mA h g⁻¹ at 50 mA g⁻¹, which is 1.6 times higher than that of VS₄), superior rate capability (76 mA h g⁻¹ at 1000 mA g⁻¹), and stable cycling performance (1500 cycles with capacity retention ratio of 93.8%). Besides that, pesudocapaticance-like contribution analysis as well as galvanostatic intermittent titration technique (GITT) further confirms the enhanced Mg²⁺ storage kinetics during such multi-electron involved electrochemical reaction process. Such discovery provides new insights into the designing of multi-electron reaction process in cathode as well as neutralizing structural change during such reaction for realizing superior electrochemical performance in energy storage devices.

Focusing on the low open circuit voltage (V_OC) and fill factor (FF) in flexible Cu₂ZnSn(S,Se)₄ (CZTSSe) solar cells, indium (In) ions are introduced into the CZTSSe absorbers near Mo foils to modify the back interface and passivate deep level defects in CZTSSe bulk concurrently for improving the performance of flexible device. The results show that In doping effectively inhibits the formation of secondary phase (Cu(S,Se)₂) and V_Sn defects. Further studies demonstrate that the barrier height at the back interface is decreased and the deep level defects (Cu_Sn defects) in CZTSSe bulk are passivated. Moreover, the carrier concentration is increased and the V_OC deficit (V_OC,def) is decreased significantly due to In doping. Finally, the flexible CZTSSe solar cell with 10.01% power conversion efficiency (PCE) has been obtained. The synergistic strategy of interface modification and bulk defects passivation through In incorporation provides a new thought for the fabrication of efficient flexible kesterite-based solar cells.

There have been reports about Fe ions boosting oxygen evolution reaction (OER) activity of Ni-based catalysts in alkaline conditions, while the origin and reason for the enhancement remains elusive. Herein, we attempt to identify the activity improvement and discover that Ni sites act as a host to attract Fe(III) to form Fe(Ni)(III) binary centres, which serve as the dynamic sites to promote OER activity and stability by cyclical formation of intermediates (Fe(III) → Fe(Ni)(III) → Fe(Ni)–OH → Fe(Ni)–O → Fe(Ni)OOH → Fe(III)) at the electrode/electrolyte interface to emit O₂. Additionally, some ions (Co(II), Ni(II), and Cr(III)) can also be the active sites to catalyze the OER process on a variety of electrodes. The Fe(III)-catalyzed overall water-splitting electrolyzer comprising bare Ni foam as the anode and Pt/Ni-Mo as the cathode demonstrates robust stability for 1600 h at 1000 mA cm⁻²@∼1.75 V. The results provide insights into the ion-catalyzed effects boosting OER performance.

Hydrogen is known for its elevated energy density and environmental compatibility and is a promising alternative to fossil fuels. Alkaline water electrolysis utilizing renewable energy sources has emerged as a means to obtain high-purity hydrogen. Nevertheless, electrocatalysts used in the process are fabricated using conventional wet chemical synthesis methods, such as sol–gel, hydrothermal, or surfactant-assisted approaches, which often necessitate intricate pretreatment procedures and are vulnerable to post-treatment contamination. Therefore, this study introduces a streamlined and environmentally conscious one-step potential-cycling approach to generate a highly efficient trimetallic nickel-iron-copper electrocatalyst in situ on nickel foam. The synthesized material exhibited remarkable performance, requiring a mere 476 mV to drive electrochemical water splitting at 100 mA cm⁻² current density in alkaline solution. Furthermore, this material was integrated into an anion exchange membrane water-splitting device and achieved an exceptionally high current density of 1 A cm⁻² at a low cell voltage of 2.13 V, outperforming the noble-metal benchmark (2.51 V). Additionally, ex situ characterizations were employed to detect transformations in the active sites during the catalytic process, revealing the structural transformations and providing inspiration for further design of electrocatalysts.

The development of aqueous battery with dual mechanisms is now arousing more and more interest. The dual mechanisms of Zn²⁺ (de)intercalation and I⁻/I₂ redox bring unexpected effects. Herein, differing from previous studies using ZnI₂ additive, this work designs an aqueous BiI₃-Zn battery with self-supplied I⁻. Ex situ tests reveal the conversion of BiI₃ into Bi (discharge) and BiOI (charge) at the 1st cycle and the dissolved I⁻ in electrolyte. The active I⁻ species enhances the specific capacity and discharge medium voltage of electrode as well as improves the generation of Zn dendrite and by-product. Furthermore, the porous hard carbon is introduced to enhance the electronic/ionic conductivity and adsorb iodine species, proven by experimental and theoretical studies. Accordingly, the well-designed BiI₃-Zn battery delivers a high reversible capacity of 182 mA h g⁻¹ at 0.2 A g⁻¹, an excellent rate capability with 88 mA h g⁻¹ at 10 A g⁻¹, and an impressive cyclability with 63% capacity retention over 20 K cycles at 10 A g⁻¹. An excellent electrochemical performance is obtained even at a high mass loading of 6 mg cm⁻². Moreover, a flexible quasi-solid-state BiI₃-Zn battery exhibits satisfactory battery performances. This work provides a new idea for designing high-performance aqueous battery with dual mechanisms.

Rational design of efficient and robust earth-abundant alkaline hydrogen evolution reaction (HER) catalysts is a key factor for developing energy conversion technologies. Currently, antiperovskite nitride CuNMn₃ has garnered significant interest due to its remarkable properties such as negative/zero thermal expansion and magnetocaloric effects. However, when utilized as hydrogen evolution catalysts, it encounters large challenge resulting from excessively strong/weak interactions with adsorbed H on Mn/Cu active sites, which leads to low HER activity. In this study, we introduce an asymmetric orbital hybridization strategy in Zn-doped Cu_1−xZn_xNMn₃ by leveraging the localization of Zn electronic states to reconfigure the electronic structures of Cu and Mn, thereby reducing the energy barrier for water dissociation and optimizing Cu and Mn active sites for hydrogen adsorption and H₂ production. Electrochemical evaluations reveal that Cu_0.85Zn_0.15NMn₃ with x  = 0.15 demonstrates exceptional electrocatalytic activity in alkaline electrolytes. A low overpotential of 52 mV at 10 mA cm⁻² and outstanding stability over a 150-h test period are achieved, surpassing commercial Pt/C. This research offers a novel strategy for enhancing HER performance by modulating asymmetric hybridization of electron orbitals between multiple metal atoms within a material structure.