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2D Ruddlesden–Popper (RP) layered metal‐halide perovskites have garnered significant interest due to their unique photoelectric properties and excellent stability. However, 2D perovskite films prepared via solution process generally exhibit multi‐quantum well structure with random well width distribution, which significantly impedes the carrier transportation. Herein, the synthesis of phase‐pure 2D (PEA)2FAPb2I7 (PEA = C8H11N, FA = CH4N2) perovskite thin films is reported in ambient environment achieved by suppressing the formation of the 3D perovskite phase. First, incorporation of MACl additive can effectively regulate the intermediate during crystallization, facilitating the formation of a metastable 3D MAxFA1‐xPbIyCl3‐y phase. Second, precise control of environmental humidity is employed to further inhibit the formation of α‐FAPbI3 phase. As a result, the perovskite intermediate composed of predominantly metastable 3D phase and 2D n = 2 phase is achieved, which is eventually transformed into 2D n = 2 perovskite during annealing, leading to markedly enhanced phase purity. Photoconductive‐type photodetectors based on the phase‐pure 2D RP perovskite films are fabricated, demonstrating a high detectivity of over 9.4 × 1012 Jones due to the improved carrier transportation. This study provides a comprehensive insight into the crystallization process of phase‐pure 2D perovskites. [ABSTRACT FROM AUTHOR]

Lattice strain engineering optimizes the interaction between the catalytic surface and adsorbed molecules. This is done by adjusting the electron and geometric structure of the metal site to achieve high electrochemical performance, but, to date, it has been rarely reported on anti‐poisoned oxygen reduction reaction (ORR). Herein, lattice‐strained Pd@PdBiCo quasi core‐shell metallic aerogels (MAs) were designed by "one‐pot and two‐step" method for anti‐poisoned ORR. Pd@PdBiCo MAs/C maintain their original activity (1.034 A mgPd−1) in electrolytes with CH3OH and CO at 0.85 V vs. reversible hydrogen electrode (RHE), outperforming the commercial Pd/C (0.156 A mgPd−1), Pd MAs/C (0.351 A mgPd−1), and PdBiCo MAs/C (0.227 A mgPd−1). Moreover, Pd@PdBiCo MAs/C also show high stability and anti‐poisoning with negligible activity decay after 8000 cycles in 0.1 m KOH+0.3 m CH3OH. These results of X‐ray photoelectron spectroscopy, CO stripping, and diffuses reflectance FTIR spectroscopy reveal that the tensile strain and strong interaction between different elements of Pd@PdBiCo MAs/C effectively optimize the electronic structure to promote O2 adsorption and activation, while suppressing CH3OH oxidation and CO adsorption, leading to high ORR activity and anti‐poisoning property. This work inspires the rational design of MAs in fuel cells and beyond. [ABSTRACT FROM AUTHOR]

The instability of palladium-based binary alloys hinders their wide application in the oxygen reduction processes. Here, we prepared Mo-doped PdCu nanoparticles with controllable dopant content and valence. Further research has revealed that Mo, particularly Mo5+, may effectively suppress the oxidation of Pd and Cu, optimize the oxygen binding of Pd, and increase catalytic activity and stability. In particular, Mo-PdCu-1/C with the highest Mo5+ content shows the best oxygen reduction reaction (ORR) mass activity (1.20 A mg−1Pd), which is 4.8 times higher than that of PdCu/C. It also exhibits outstanding stability, retaining 80.8% of the original mass activity after 20 000 cycles. This study clearly explains the mechanism by which Mo doping affects the performance and provides a reference for further optimization of catalyst performance for fuel cell industrialization. [ABSTRACT FROM AUTHOR]

To achieve carbon neutrality, electrocatalysis has the potential to be applied in the technological upgrading of numerous industries. Therefore, the search for high-performance catalysts has become an important topic. To accelerate the discovery of new electrocatalysts, emerging data-driven strategies have been considered promising approaches. In particular, research methods represented by machine learning (ML) have permeated all aspects of electrocatalyst development, including synthesis, characterization, and simulation, which have given rise to numerous new ideas for catalytic-related data generation and analysis. Herein, this review focuses on the systematic construction of a data-driven electrocatalyst design framework. First, we introduce the principles for the basic steps for implementing data-driven electrocatalyst research, including data generation, data preprocessing, and data analysis. Subsequently, the progress of ML methods to design promising electrocatalytic materials (e.g., metals, alloys, and oxides) for numerous typical electrochemical reactions is summarized. Finally, the current challenges and opportunities are outlined for the future of data-driven electrocatalyst design. [ABSTRACT FROM AUTHOR]

Layered manganese-based oxide cathodes have attracted extensive attention in sodium-ion batteries (SIBs) due to their low cost and high volumetric energy density. However, Na+/vacancy ordering destabilizes the host structure and retards Na+ diffusion. Herein, we report that this issue can be solved by introducing the highly electropositive Sn4+ to tune charge distribution and then reduce electron delocalization as well as in-plane Na+–Na+ electrostatic repulsions. The disordered Na vacancy arrangement and suppressed P′2 ↔ P2 phase transition enable P′2-Na0.67Mn0.95Sn0.05O2 with fast Na+ migration and ultralow strain (<1%) during cycles. Thus, high reversible capacity of 131.2 mA h g−1 and coulombic efficiency of 99.77% are achieved at 50 mA g−1 after 200 cycles. Besides, based on a low reaction energy barrier, the electrode exhibits high Na-storage activity in a wide temperature range of −20 to 70 °C. These observations provide an effective strategy for designing high-performance cathode materials in rechargeable SIBs and beyond. [ABSTRACT FROM AUTHOR]

A novel biphasic layered Na0.62Ni0.33Mn0.62Sb0.05O2 cathode is introduced which can be easily synthesized via a solid-state reaction method. Compared with its monophasic counterpart Na0.67Ni0.33Mn0.67O2, biphasic Na0.62Ni0.33Mn0.62Sb0.05O2 displays a smoother (dis)charge profile, superior rate capability along with splendid cycling performance. Structural and kinetic studies respectively demonstrate extremely small volume strain and rapid charge transfer during the electrochemical process. [ABSTRACT FROM AUTHOR]

Manganese-based layered cathode materials for sodium-ion batteries are attractive on account of the superiorities of high capacity and cost effectiveness. Nevertheless, the materials suffer from sluggish kinetics and drastic volume changes during the extraction and insertion of Na ions, thereby resulting in inferior rate capability and rapid cycling decay. Herein, a strategy of integrating structurally stable P2 into the O′3 phase for robust Mn-based layered oxides is proposed, which not only buffers the drastic lattice strain, but also enhances Na-ion diffusion. The P2/O′3-biphasic NaMn0.89Cu0.08Sb0.03O2 cathode provides a high reversible capacity of 204 mA h g−1, an admirable capacity retention of 80% after 150 cycles and a superior rate capability with 120 mA h g−1 capacity at 2C rate, in stark contrast to O′3 NaMnO2. The results show that the volume change and lattice parameter c have been respectively reduced to 10.5% and 3.3% after P2 integration, compared with 27.04% and 23.39% for the original O′3 NaMnO2, and the Na-ion diffusion coefficient has been evidently increased from 10−12 in the pristine O′3 NaMnO2 to 10−11 in the P2/O′3 biphase. The findings highlight the significance and superiority of the composite electrode and provide new insights for the rational design of high-performance sodium-ion batteries. [ABSTRACT FROM AUTHOR]

An air-stable Na0.67Mn0.7Cu0.15Ti0.15O2 (NMCT) has been synthesized using a solid-state method. It displays a reversible capacity of 170 mA h g−1 and a capacity retention of 82.5% after 300 cycles. NMCT also exhibits good structural stability upon electrochemical de/intercalation processes as observed by operando XRD. And the result shows that the unit-cell volume change of NMCT during the whole process of Na+ de/intercalation is only 3.2%. These data indicate that NMCT is a promising cathode material for sodium ion batteries (SIBs). [ABSTRACT FROM AUTHOR]

Nowadays, oxygen-related anionic redox reactions (ARRs) attract considerable research attention because of the potential of expanding stored energy in cathode materials for Li/Na-ion batteries. In general, irreversible lattice oxygen loss and associated structural distortion are considered to be a threat to the practical application of the ARRs process. Herein, the anionic redox behavior in an O3-type layered NaMg0.67Ru0.33O2 (Ru5+) cathode has been systematically investigated by various in/ex situ spectroscopic characterization techniques. Unexpectedly, compared to the complex phase transitions (O3/O′3/P3) and sluggish dynamic processes observed within ARR-free O3-type NaMg0.5Ru0.5O2 (Ru4+), the distorted structure induced by initial oxygen loss within the NaMg0.67Ru0.33O2 (Ru5+) cathode reveals a simple phase transition (O3/O′3) and better structural stability during cycling. This anomaly triggers us to make a fair assessment of the distorted structure induced by loss of lattice oxygen. Furthermore, based on the abnormal phenomenon referred to above, to restrain redundant oxygen loss, appropriate lattice oxygen loss can be rationally considered as a structural modification method for moderate phase transition processes during long-term cycling. [ABSTRACT FROM AUTHOR]

A layered cathode for K-ion storage was achieved using electrochemical ion-exchange. It delivers a large specific capacity, superior rate performance and excellent cycling performance. Interestingly, it was found from the GITT results that the K ion diffusion coefficients were above 10−12 cm2 s−1, comparable with that of Na-ion in the layered structure. [ABSTRACT FROM AUTHOR]

An O3-layered oxide of NaFe0.25Mn0.25Ni0.25Ti0.25O2 was successfully synthesized. When serving as a cathode during sodium-ion cell operation, it exhibits excellent electrochemical performance. The operando XRD result reveals a reversible O3 → O3 + P3 → O1 + P3 phase transformation of NaFe0.25Mn0.25Ni0.25Ti0.25O2 during an electrochemical process. [ABSTRACT FROM AUTHOR]

Abstract: Sodium‐ion batteries with abundant and low‐cost sodium resources is a promising alternative to Li‐ion batteries in large‐scale energy applications. While the anode materials, due to their insufficient cycling life and insecure voltage, could not still satisfy the market demands, especially in the wide‐temperature fields, here, a high‐crystallinity anode material with post‐spinel structure, namely NaV1.25Ti0.75O4, which always maintains excellent electrochemical performance at the widely variable temperatures, is reported. The results indicate that this anode delivers a high‐safety and ultrastable room‐temperature performance (i.e., an average output voltage of 0.7 V vs Na+/Na and the ultralong cycling life over 10 000 cycles) and good wide‐temperature performance (below 9% capacity variation at 60 and −20 °C compared to that at 25 °C). These excellent achievements could benefit from the long durability and stability of 1D channels and superfast ion diffusion in a temperature‐dependent range. This finding provides a promising strategy to construct the safe and stable full‐cell prototypes and promotes the wide‐temperature application of sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Based on cation/anion graphite intercalation chemistry (GIC) processes, dual‐graphite batteries promise to be an energy storage device of high safety and low cost. However, few single electrolyte systems can simultaneously meet the requirements of both high oxidative stability during high voltage anion‐GIC on cathode and high reversibility upon cation‐GIC on anode. Thus, in order to rigidly remedy the irreversible capacity loss, excessive electrode materials need to be fabricated within full cell, resulting in an imbalance toward capacity‐dependent mass loading proportion between both electrodes. This work introduces a hybrid (dual‐organic) electrolytes design strategy into this promising technology. Segregated by a Nafion‐based separator, an ionic liquid electrolyte within the cathodic side can endure high operation potentials, while high Li‐GIC reversibility can be achieved in a superconcentrated ether‐based electrolyte on the anode side. On a mechanistic level, various cation‐GIC processes conducted in different electrolyte systems are clearly revealed and are summarized based on systematical characterizations. More importantly, after synergistically tuning the advantage and drawback of each electrolyte in this hybrid system, the dual‐graphite full cell assembled with capacity‐equivalent graphite‐based electrodes (1:1 mass loading) demonstrates superior long‐term cycling stability with ultrahigh capacity retention for over 3000 cycles. [ABSTRACT FROM AUTHOR]

Rechargeable lithium metal batteries have been regarded as one of the most attractive high-energy-density batteries due to their large specific capacity and the lowest reduction potential of metallic lithium. However, the uncontrollable Li dendrite growth and the resulting unstable interfaces during repeated Li plating/stripping lead to severe safety issues and a short cycle life, which are aggravated especially at a high current density. Herein, we present an organic/inorganic composite protective layer via pretreating the lithium metal in an Mn(NO3)2-containing carbonate electrolyte, not only enabling stable lithium deposition and formation with a prolonged cycle life, but also providing a record high rate of 20 mA cm−2 with a minimized overpotential of 60 mV in a symmetric lithium cell. Results indicate that such an artificial protective film could effectively prolong the cycle life of Li☋Cu cells, and greatly improve the comprehensive electrochemical performance of Li☋LiMn2O4 cells. The pretreated-Li☋LiMn2O4 cells show an outstanding cycling performance with 83% capacity retention over 200 cycles at a high rate of 2C and a high temperature of 55 °C, and exhibit robust recovery capabilities with a high capacity and coulombic efficiency after the cycles at 10C. These findings highlight the significance of a protective layer in stabilizing a Li metal anode and pave a new way for designing high-energy batteries for practical utilization. [ABSTRACT FROM AUTHOR]

Abstract: Sodium–oxygen batteries based on abundant sodium resource have caused increasing interest due to their high energy density and low cost. However, the reactive sodium anode always induces unpredictable side reactions especially in oxygen atmosphere and battery short circuit due to the uncontrolled formation of dendrites. Here, an accessible method to grow a durable protective passivation film on the surface of sodium anodes is reported. The sodium fluoride‐rich film efficiently suppresses O2 crossover and electrolyte decay related side reactions on sodium anodes. Significantly, no dendrites form during long‐term stripping/plating cycles. Benefiting from these superiorities, sodium–oxygen batteries achieve impressive improvement of discharge–charge ability and reliable safety. These results enrich the approaches for stabilizing sodium anodes and allow researchers to focus on the investigations on the air cathode and the overall chemistry of sodium–oxygen batteries. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries are intensively investigated for large-scale energy storage due to the favorable sodium availability. However, the anode materials have encountered numerous problems, such as insufficient cycling performance, dissatisfactory capacity, and low safety. Here, a novel post-spinel anode material, i.e., single-crystalline NaVSnO4, is presented with the confined 1D channels and the shortest diffusion path. This material delivers an ultra long cycling life (84% capacity retention after 10 000 cycles), a high discharging capacity (163 mA h g−1), and a safe average potential of 0.84 V. Results indicate that the post-spinel structure is well maintained over 10 000 cycles, surprisingly, with 0.9% volume change, the Sn4+/Sn2+ based redox enables two sodium ions for reversible release and uptake, and the diffusion coefficient of sodium ions is characterized by 1.26 × 10−11 cm2 s−1. The findings of this study provide a new insight into design of new frameworks with polyelectronic transfers for full performance electrode materials of sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Among various platinum (Pt)-based nanostructures, porous or hollow ones are of great importance because they exhibit fantastic oxygen reduction reaction (ORR) enhancements and maximize atomic utilization by exposing both exterior and interior surfaces. Here, a new class of porous Pt3Ni nanowires (NWs) with 1D architecture, an ultrathin Pt-rich shell, high index facets, and a highly open structure is designed via a selective etching strategy by using the phase and composition segregated Pt-Ni NWs as the starting material. The porous feature of Pt3Ni NWs can be readily fulfilled by changing the Pt/Ni atomic ratio of the starting Pt-Ni NWs. Such porous Pt3Ni NWs show extraordinary activity and stability enhancements toward methanol oxidation reaction and ORR. The porous Pt3Ni NWs can deliver ORR mass activity of 5.60 A mg−1, which is 37.3-fold higher than that of the Pt/C. They also show outstanding stability with negligible activity loss after 20 000 cycles. This study offers a unique approach for the design of complex nanostructures as efficient catalysts through precisely tailoring. [ABSTRACT FROM AUTHOR]

Although extensive efforts have been devoted to the pursuit of promising electrocatalysts to lower the overpotential of the oxygen evolution reaction (OER), the design of low-costing earth-abundant OER electrocatalysts with desirable performance remains a formidable challenge. Herein, we demonstrate a facile strategy to create ultrathin NiFe layered double hydroxide (LDH) nanosheets grown on carbon nanotubes (CNTs) as superior OER electrocatalysts. Different from previously reported NiFe-LDH nanomaterials, the newly generated NiFe-LDH@CNTs exhibit distinct features, including ultrathin building blocks, a 1 D structure, 3 D hierarchical architecture, and the electron effect. Significantly, it was revealed that doping Fe into Ni-LDH@CNTs optimized the performance for the OER; Ni8Fe-LDH@CNTs was found to be the most active and is one of the best non-noble metal catalysts for the OER to date. The catalysts are also highly stable for the OER with little potential shift after an 18 h test. Both X-band electron spin resonance and X-ray photoelectron spectroscopy indicated that optimized iron doping resulted in intense interaction between Ni x+ and Fe3+ and electron transfer from Ni x+ to Fe3+, which thus boosted the OER performance. [ABSTRACT FROM AUTHOR]

The design of high-performance electrocatalysts for the alkaline hydrogen evolution reaction (HER) is highly desirable for the development of alkaline water electrolysis. Phase- and interface-engineered platinum-nickel nanowires (Pt-Ni NWs) are highly efficient electrocatalysts for alkaline HER. The phase and interface engineering is achieved by simply annealing the pristine Pt-Ni NWs under a controlled atmosphere. Impressively, the newly generated nanomaterials exhibit superior activity for the alkaline HER, outperforming the pristine Pt-Ni NWs and commercial Pt/C, and also represent the best alkaline HER catalysts to date. The enhanced HER activities are attributed to the superior phase and interface structures in the engineered Pt-Ni NWs. [ABSTRACT FROM AUTHOR]

The development of superior non-platinum electrocatalysts for enhancing the electrocatalytic activity and stability for the oxygen-reduction reaction (ORR) and liquid fuel oxidation reaction is very important for the commercialization of fuel cells, but still a great challenge. Herein, we demonstrate a new colloidal chemistry technique for making structurally ordered PdCu-based nanoparticles (NPs) with composition control from PdCu to PdCuNi and PtCuCo. Under the dual tuning on the composition and intermetallic phase, the ordered PdCuCo NPs exhibit better activity and much enhanced stability for ORR and ethanol-oxidation reaction (EOR) than those of disordered PdCuM NPs, the commercial Pt/C and Pd/C catalysts. The density functional theory (DFT) calculations reveal that the improved ORR activity on the PdCuM NPs stems from the catalytically active hollow sites arising from the ligand effect and the compressive strain on the Pd surface owing to the smaller atomic size of Cu, Co, and Ni. [ABSTRACT FROM AUTHOR]

Na‐ion batteries are promising for large‐scale energy storage due to the low cost and earth abundance of the sodium resource. Despite tremendous efforts being made to improve the battery performance, some fundamental mechanism issues still are not sufficiently understood. One such issue in the most popularized layered structure materials is the potential cation migration into sodium layers, which would highly affect the energy efficiency thus hindering its widespread use in the future. Here a systematic study of the cation migration in layered structure materials is presented and its relationship with voltage hysteresis is disclosed. Using the high‐angle annular dark field‐scanning transmission electron microscopy and in operando X‐ray diffraction as implements, for the first time, the reversible migration of the transition metal between transition metal layers and sodium layers is captured. The research inspires a novel insight into the cation migration related layered materials, which should be considered for future battery design toward conventional use. [ABSTRACT FROM AUTHOR]