Advances in Manganese‐Based Oxides Cathodic Electrocatalysts for Li–Air Batteries

Li–air batteries, characteristic of superhigh theoretical specific energy density, cost‐efficiency, and environment‐friendly merits, have aroused ever‐increasing attention. Nevertheless, relatively low Coulomb efficiency, severe potential hysteresis, and poor rate capability, which mainly result from sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) kinetics, as well as pitiful cycle stability caused by parasitic reactions, extremely limit their practical applications. Manganese (Mn)‐based oxides and their composites can exhibit high ORR and OER activities, reduce charge/discharge overpotential, and improve the cycling stability when used as cathodic catalyst materials. Herein, energy storage mechanisms for Li–air batteries are summarized, followed by a systematic overview of the progress of manganese‐based oxides (MnO₂ with different crystal structures, MnO, MnOOH, Mn₂O₃, Mn₃O₄, MnOx, perovskite‐type and spinel‐type manganese oxides, etc.) cathodic materials for Li–air batteries in the recent years. The focus lies on the effects of crystal structure, design strategy, chemical composition, and microscopic physical parameters on ORR and OER activities of various Mn‐based oxides, and even the overall performance of Li–air batteries. Finally, a prospect of the research for Mn‐based oxides cathodic catalysts in the future is made, and some new insights for more reasonable design of Mn‐based oxides electrocatalysts with higher catalytic efficiency are provided.     

Multifunctional Synthesis Approach of In:CuCrO2 Nanoparticles for Hole Transport Layer in High‐Performance Perovskite Solar Cells

While there are very limited studies of doped ternary metal oxide based hole transport materials, a multifunctional synthesis approach of In doped CuCrO₂ nanoparticles (NPs) as efficient hole transport layers (HTLs) including simplifying the synthesis requirements is proposed, enabling doping and achievement of treatment‐free HTLs. Remarkably, compared with conventional methods for synthesizing CuCrO₂ NPs, the newly proposed azeotropic promoted approach dramatically reduces the reaction time by 90% and the calcination temperature by one‐third, which not only promotes high throughput production but also reduces power consumption and cost in synthesis. Equally important, indium is successfully doped into CuCrO₂, which is fundamentally difficult in low temperature processes. The In doping offers less d–d transition of Cr³⁺ and p‐type doping characteristics for improving HTL transmittance and conductivity, respectively. Interestingly, In doped CuCrO₂ HTL with these improvements can be achieved by a simple ambient‐condition process and exhibits thermal stability up to 200 °C, which allows perovskite solar cells (PSCs) to achieve a power conversion efficiency of 20.54%. Meanwhile, the devices show good repeatability and photostability. Consequently, the work contributes to establishing a simple approach to realize pristine and doped multinary oxides based HTL for the development of practical and high performing PSCs.     

Nanoflake Arrays of Lithiophilic Metal Oxides for the Ultra‐Stable Anodes of Lithium‐Metal Batteries

A molten lithium infusion strategy has been proposed to prepare stable Li‐metal anodes to overcome the serious issues associated with dendrite formation and infinite volume change during cycling of lithium‐metal batteries. Stable host materials with superior wettability of molten Li are the prerequisite. Here, it is demonstrated that a series of strong oxidizing metal oxides, including MnO₂, Co₃O₄, and SnO₂, show superior lithiophilicity due to their high chemical reactivity with Li. Composite lithium‐metal anodes fabricated via melt infusion of lithium into graphene foams decorated by these metal oxide nanoflake arrays successfully control the formation and growth of Li dendrites and alleviate volume change during cycling. A resulting Li‐Mn/graphene composite anode demonstrates a super‐long and stable lifetime for repeated Li plating/stripping of 800 cycles at 1 mA cm^?2 without voltage fluctuation, which is eight times longer than the normal lifespan of a bare Li foil under the same conditions. Furthermore, excellent rate capability and cyclability are realized in full‐cell batteries with Li‐Mn/graphene composite anodes and LiCoO₂ cathodes. These results show a major advancement in developing a stable Li anode for lithium‐metal batteries.     

Solution‐Growth Strategy for Large‐Scale “CuGaO2 Nanoplate/ZnS Microsphere” Heterostructure Arrays with Enhanced UV Adsorption and Optoelectronic Properties

Intrinsically p‐type conductivity and a wide bandgap of ≈3.6 V endow inorganic delafossite CuGaO₂ with great promise for fabricating high‐performance UV photodetectors. Nevertheless, CuGaO₂‐based optoelectronic devices hindered because the intrinsic direct transitions are symmetry forbidden in CuGaO₂. This study reports a large‐area synthesis of “CuGaO₂ nanoplate/ZnS microsphere” heterostructure arrays using a facile solution‐based strategy associated with an oil/water interfacial self‐assembly approach. It is found that a large number of ZnS microspheres with a polycrystalline structure grow on the top surface of CuGaO₂ hexagonal platelets through Ostwald ripening mechanism, forming high‐density p–n heterojunctions. A parabolic dependence between the size of ZnS microsphere and the growth time is confirmed in this growth. The UV light adsorption of the heterostructure CuGaO₂/ZnS thin film is two times higher than that of the pristine CuGaO₂ thin film. Furthermore, the as‐designed “CuGaO₂ nanoplate/ZnS microsphere” heterostructure arrays exhibit enhanced photoresponse properties. This work offers a new insight into the rational design of optoelectronic devices from the synergetic effect of p‐type 2D nanoplates as well as n‐type nanostructures such as ZnS, ZnO, CdS, and CdO.     

Holey 2D Nanosheets of Low‐Valent Manganese Oxides with an Excellent Oxygen Catalytic Activity and a High Functionality as a Catalyst for Li–O2 Batteries

Holey 2D nanosheets of low‐valent Mn₂O₃ can be synthesized by thermally induced phase transition of exfoliated layered MnO₂ nanosheets. The heat treatment of layered MnO₂ nanosheets at elevated temperatures leads not only to transitions to low‐valent manganese oxides but also to the creation of surface hole in the 2D nanosheet crystallites. Despite distinct phase transitions, highly anisotropic 2D morphology of the precursor MnO₂ material remains intact upon the heat treatment whereas the diameter of surface hole becomes larger with increasing heating temperature. The obtained holey 2D Mn₂O₃ nanosheets show promising electrocatalyst performances for oxygen evolution reaction, which are much superior to that of nonporous Mn₂O₃ crystal. Among the present materials, the holey Mn₂O₃ nanosheet calcined at 500 °C displays the best electrocatalyst functionality with markedly decreased overpotential, indicating the importance of heating condition in optimizing the electrocatalytic activity. Of prime importance is that this material shows much better catalytic activity for Li–O₂ batteries than does nonporous Mn₂O₃, underscoring the critical role of porous 2D morphology in this functionality. This study clearly demonstrates the unique advantage of holey 2D nanosheet morphology in exploring economically feasible transition metal oxide‐based electrocatalysts and electrodes for Li–O₂ batteries.     

Faster Activation and Slower Capacity/Voltage Fading: A Bifunctional Urea Treatment on Lithium‐Rich Cathode Materials

Li‐rich layered oxides are promising cathode materials for next‐generation Li‐ion batteries because of their extraordinary specific capacity. However, the activation process of the key active component Li₂MnO₃ in Li‐rich materials is kinetically slow, and the complex phase transformation with electrode/electrolyte side reactions causes fast capacity/voltage fading. Herein, a simple thermal treatment strategy is reported to simultaneously tackle these challenges. The introduction of a urea thermal treatment on Li‐rich material Li_1.87Mn_0.94Ni_0.19O₃ leads to oxygen deficiencies and partially reduced Mn ions on the oxide surface for activating the Li‐rich phase. In situ synchrotron study confirms that the urea‐treated cathode shows much faster Li extraction from both Li and transition metal layers with less oxygen evolution upon charging than that of untreated counterparts. Moreover, the decomposition products of urea during thermal treatment subsequently deposit on the surface of cathode material, leading to a unique passivation layer against side reactions between electrode and electrolyte. Soft X‐ray absorption spectroscopy reveals the structural evolution mechanism with a significantly suppressed dissolution of Mn species over cycling measurement. The urea‐treated Li_1.87Mn_0.94Ni_0.19O₃ shows accelerated activation kinetics to reach high capacity of 270 mA h g^–1 and demonstrates excellent capacity retention of 98.49% over 300 cycles with slower voltage decay.     

Layered Double Hydroxide Nano‐ and Microstructures Grown Directly on Metal Substrates and Their Calcined Products for Application as Li‐Ion Battery Electrodes

Layered double hydroxide (LDH) nano‐ and microstructures with controllable size and morphology have been fabricated on “bivalent metal” substrates such as zinc and copper by a one‐step, room‐temperature process, in which metal substrates act as both reactants and supports. By manipulating the concentration of NH₃ · H₂O, the thickness and lateral size of the LDH materials can be tuned from several tens of nanometers to several hundreds of nanometers and from several hundreds of nanometers to several micrometers, respectively. This method is general and may be readily extended to any other alkali‐resisted substrate coated with Zn and Cu. As an example, Zn‐covered stainless steel foil has been shown to be effective for the growth of a Zn? Al LDH film. After calcinating the as‐grown LDH at high temperature (650 °C) in argon gas, a ZnO/ZnAl₂O₄ porous nanosheet film is obtained, which is then directly used for the first time as the anode material for Li‐ion batteries with the operating voltage window of 0.05–2.5 V (vs. Li). The result demonstrates that ZnO/ZnAl₂O₄ has higher discharge and charge capacities and considerably better cycling stability compared to pure ZnO (Li insertion/extraction rate: 200 or 500 mA g^?1). The improved electrochemical performance can be ascribed to the buffering effect of the inactive matrix ZnAl₂O₄ by relieving the stress caused by the volume change during charge–discharge cycling. This work represents a successful example for the development of promising ZnO‐based anode materials for Li‐ion batteries.     

Protein‐Directed Metal Oxide Nanoflakes with Tandem Enzyme‐Like Characteristics: Colorimetric Glucose Sensing Based on One‐Pot Enzyme‐Free Cascade Catalysis

It is difficult and significant to realize the aim of “one‐pot” and “nonenzyme” for traditional colorimetric detection of blood glucose. The synthesis of nanomaterials with 2D morphology is also a challenge for the bovine serum albumin (BSA)‐directed method. Here, the BSA‐directed synthesis avenue for metal oxide with 2D nanomorphology is developed. MnO₂ nanoflakes (NFs) with controllable morphology can be obtained by changing the synthesis conditions. Fortunately, not only is the glucose oxidase (GOx)‐like nanozyme (MnO₂ NFs) discovered, but MnO₂ NFs also show dual enzyme activities (GOx‐like activity and peroxidase‐like activity) in similar pH range. That is to say, a “tandem nanozyme” (nanomaterial with tandem enzyme‐like characteristics) is presented here. Further, the one‐pot nonenzymatic strategy is proposed for the colorimetric detection of glucose, where the oxidation of glucose and the colorimetric detection of H₂O₂ are simultaneously conducted under the catalysis of the single nanozyme (MnO₂ NFs). The method shows high sensitivity, low limit of detection, and short detection time, due to the proximity effect and in situ reaction. The as‐synthesized 2D tandem nanozyme expands the species of nanozymes, and the proposed strategy breaks traditional colorimetric detection process, accomplishing the purposes of “one‐pot” and “nonenzyme” in the true sense.     

Doping Rules and Doping Prototypes in A2BO4 Spinel Oxides

A₂BO₄ spinels constitute one of the largest groups of oxides, with potential applications in many areas of technology, including (transparent) conducting layers in solar cells. However, the electrical properties of most spinel oxides remain unknown and poorly controlled. Indeed, a significant bottleneck hindering widespread use of spinels as advanced electronic materials is the lack of understanding of the key defects rendering them as p‐type or n‐type conductors. By applying first‐principles defect calculations to a large number of spinel oxides the major trends controlling their dopability are uncovered. Anti‐site defects are the main source of electrical conductivity in these compounds. The trends in anti‐sites transition levels are systemized, revealing fundamental “doping rules”, so as to guide practical doping of these oxides. Four distinct doping types (DTs) emerge from a high‐throughput screening of a large number of spinel oxides: i) donor above acceptor, both are in the gap, i.e., both are electrically active and compensated (DT‐1), ii) acceptor above donor, and only acceptor is in the gap, i.e., only acceptor is electrically active (DT‐2), iii) acceptor above donor, and only donor is in the gap, i.e., only donor is electrically active (DT3), and iv) acceptor above donor in the gap, i.e., both donor and acceptor are electrically active, but not compensated (DT‐4). Donors and acceptors in DT‐1 materials compensate each other to a varying degree, and external doping is limited due to Fermi level pinning. Acceptors in DT‐2 and donors in DT‐3 are uncompensated and may ionize and create holes or electrons, and external doping can further enhance their concentration. Donor and acceptor in DT‐4 materials do not compensate each other, and when the net concentration of carriers is small due to deep levels, it can be enhanced by external doping.     

Proton Conduction in a Tyrosine‐Rich Peptide/Manganese Oxide Hybrid Nanofilm

Proton conduction is an essential process that regulates an integral part of several enzymatic catalyses and bioenergetics. Proton flows in biological entities are sensitively controlled by several mechanisms. To understand and manipulate proton conduction in biosystems, several studies have investigated bulk proton conduction in biomaterials such as polyaspartic acid, collagen, reflectin, serum albumin mats, and eumelanin. However, little is known about the bulk proton conductivity of short peptides and their sequence‐dependent behavior. Here, this paper focuses on a short tyrosine‐rich peptide that has redox‐active and cross‐linkable phenol groups. The spin‐coated peptide nanofilm is immersed in potassium permanganate solution to induce cross‐linking and oxidation, simultaneously leading to hybridization with manganese oxide (MnO_x ). The peptide/MnO_x hybrid nanofilm can efficiently transport protons, and its proton conductivity is ≈18.6 mS cm^?1 at room temperature. This value is much higher than that of biomaterials and comparable to those of other synthetic proton‐conducting materials. These results suggest that peptide‐based hybrid materials can be a promising new class of proton conductor.     

Wide‐Range‐Tunable p‐Type Conductivity of Transparent CuI1−xBrx Alloy

Transparent p‐type semiconductors with wide‐range tunability of the hole density are rare. Developing such materials is a challenge in the field of transparent electronics that utilize invisible electric circuits. In this paper, a CuI–CuBr alloy (CuI_1?xBr_x) is proposed as a hole‐density‐tunable p‐type transparent semiconductor that can be fabricated at room temperature. First‐principles calculations predict that the acceptor state originating from copper vacancies in CuBr is deeper than that in CuI, leading to the hypothesis that the hole density in CuI_1?xBr_x can be tuned over a wide range by varying x between 0 and 1. The experimental results support this hypothesis. The hole density in CuI_1?xBr_x polycrystalline alloy layers can be tuned by over three orders of magnitude (10¹⁷–10²⁰ cm^?3) by varying x. In other words, the p‐type conductivity of the CuI_1?xBr_x alloy shows metallic and semiconducting properties. Such alloy layers can be prepared at room temperature without sacrificing transparency. Furthermore, CuI_1?xBr_x forms transparent p–n diodes with n‐type amorphous In–Ga–Zn–O layers, and these diodes have satisfactory rectification performance. Therefore, CuI_1?xBr_x alloy is an excellent p‐type transparent semiconductor for which the p‐type conductivity can be tailored in a wide range.     

Understanding the Origin of Li2MnO3 Activation in Li‐Rich Cathode Materials for Lithium‐Ion Batteries

Li‐rich layered cathode materials have been considered as a family of promising high‐energy density cathode materials for next generation lithium‐ion batteries (LIBs). However, although activation of the Li₂MnO₃ phase is known to play an essential role in providing superior capacity, the mechanism of activation of the Li₂MnO₃ phase in Li‐rich cathode materials is still not fully understood. In this work, an interesting Li‐rich cathode material Li_1.87Mn_0.94Ni_0.19O₃ is reported where the Li₂MnO₃ phase activation process can be effectively controlled due to the relatively low level of Ni doping. Such a unique feature offers the possibility of investigating the detailed activation mechanism by examining the intermediate states and phases of the Li₂MnO₃ during the controlled activation process. Combining powerful synchrotron in situ X‐ray diffraction analysis and observations using advanced scanning transmission electron microscopy equipped with a high angle annular dark field detector, it has been revealed that the subreaction of O₂ generation may feature a much faster kinetics than the transition metal diffusion during the Li₂MnO₃ activation process, indicating that the latter plays a crucial role in determining the Li₂MnO₃ activation rate and leading to the unusual stepwise capacity increase over charging cycles.     

Hydrothermal Growth of Manganese Dioxide into Three‐Dimensional Hierarchical Nanoarchitectures

Novel three‐dimensional (3D) hierarchical nanoarchitectures of ?‐MnO₂ have been synthesized by a simple chemical route without the addition of any surfactants or organic templates. The self‐organized crystals consist of a major ?‐MnO₂ dipyramidal single crystal axis and six secondary branches, which are arrays of single‐crystal ?‐MnO₂ nanobelts. The growth directions of the nanobelts are perpendicular to the central dipyramidal axis, which shows sixfold symmetry. The shape of the ?‐MnO₂ assembly can be controlled by the reaction temperature. The morphology of ?‐MnO₂ changes from a six‐branched star‐like shape to a hexagonal dipyramidal morphology when the temperature is increased from 160 to 180 °C. A possible growth mechanism is proposed. The synthesized ?‐MnO₂ shows both semiconducting and magnetic properties. These materials exhibit ferromagnetic behavior below 25 K and paramagnetic behavior above 25 K. The ?‐MnO₂ system may have potential applications in areas such as fabrication of nanoscale spintronic materials, catalysis, and sensors.     

Design of High‐Performance Disordered Half‐Heusler Thermoelectric Materials Using 18‐Electron Rule

Ternary half‐Heusler (HH) alloys display intriguing functionalities ranging from thermoelectric to magnetic and topological properties. For thermoelectric applications, stable HH alloys with a nominal valence electron count (VEC) of 18 per formula or defective HH alloys with a VEC of 17 or 19 are assumed to be promising candidates. Inspired by the pioneering efforts to design a TiFe_0.5Ni_0.5Sb double HH alloy by combining 17‐electron TiFeSb and 19‐electron TiNiSb HH alloys, both high‐performance n‐type and p‐type materials based on the same parent TiFe_0.5Ni_0.5Sb are developed. First‐principles calculation results demonstrate their beneficial band structure having a high band degeneracy that contributes to their large effective mass and thereby maintains their high Seebeck coefficient values. Due to the strong Fe/Ni disorder effect, TiFe_0.5Ni_0.5Sb exhibits a much lower lattice thermal conductivity than does TiCoSb, consistent with very recently reported results. Furthermore, tuning the ratio of Fe and Ni leads to achieving both p‐ and n‐types, and alloying Ti by Hf further enhances the thermoelectric performance significantly. A peak ZT of ≈1 and ≈0.7 at 973 K are achieved in the p‐type and n‐type based on the same parent, respectively, which are beneficial and promising for real applications.     

Searching General Sufficient‐and‐Necessary Conditions for Ultrafast Hydrogen‐Evolving Electrocatalysis

The development of cost‐effective and high‐performance electrocatalysts for the hydrogen evolution reaction (HER) is one critical step toward successful transition into a sustainable green energy era. Different from previous design strategies based on single parameter, here the necessary and sufficient conditions are proposed to develop bulk non‐noble metal oxides which are generally considered inactive toward HER in alkaline solutions: i) multiple active sites for different reaction intermediates and ii) a short reaction path created by ordered distribution and appropriate numbers of these active sites. Computational studies predict that a synergistic interplay between the ordered oxygen vacancies (at pyramidal high‐spin Co³⁺ sites) and the O 2p ligand holes (OLH; at metallic octahedral intermediate‐spin Co⁴⁺ sites) in RBaCo₂O_5.5+δ (δ = 1/4; R = lanthanides) can produce a near‐ideal HER reaction path to adsorb H₂O and release H₂, respectively. Experimentally, the as‐synthesized (Gd_0.5La_0.5)BaCo₂O_5.75 outperforms the state‐of‐the‐art Pt/C catalyst in many aspects. The proof‐of‐concept results reveal that the simultaneous possession of ordered oxygen vacancies and an appropriate number of OLH can realize a near‐optimal synergistic catalytic effect, which is pivotal for rational design of oxygen‐containing materials.     

Water‐Induced Scandium Oxide Dielectric for Low‐Operating Voltage n‐ and p‐Type Metal‐Oxide Thin‐Film Transistors

Solution‐processed metal‐oxide thin films based on high dielectric constant (k) materials have been extensively studied for use in low‐cost and high‐performance thin‐film transistors (TFTs). Here, scandium oxide (ScO_x) is fabricated as a TFT dielectric with excellent electrical properties using a novel water‐inducement method. The thin films are annealed at various temperatures and characterized by using X‐ray diffraction, atomic‐force microscopy, X‐ray photoelectron spectroscopy, optical spectroscopy, and a series of electrical measurements. The optimized ScO_x thin film exhibits a low‐leakage current density of 0.2 nA cm^?2 at 2 MV cm^?1, a large areal capacitance of 460 nF cm^?2 at 20 Hz and a permittivity of 12.1. To verify the possible applications of ScO_x thin films as the gate dielectric in complementary metal oxide semiconductor (CMOS) electronics, they were integrated in both n‐type InZnO (IZO) and p‐type CuO TFTs for testing. The water‐induced full oxide IZO/ScO_x TFTs exhibit an excellent performance, including a high electron mobility of 27.7 cm² V^?1 s^?1, a large current ratio (I_on/I_off) of 2.7 × 10⁷ and high stability. Moreover, as far as we know it is the first time that solution‐processed p‐type oxide TFTs based on a high‐k dielectric are achieved. The as‐fabricated p‐type CuO/ScO_x TFTs exhibit a large I_on/I_off of around 10⁵ and a hole mobility of 0.8 cm² V^?1 at an operating voltage of 3 V. To the best of our knowledge, these electrical parameters are among the highest performances for solution‐processed p‐type TFTs, which represents a great step towards the achievement of low‐cost, all‐oxide, and low‐power consumption CMOS logics.     

Crystalline Mesoporous Complex Oxides: Porosity‐Controlled Electromagnetic Response

A colloidal‐amphiphile‐templated growth is developed to synthesize mesoporous complex oxides with highly crystalline frameworks. Organosilane‐containing colloidal templates can convert into thermally stable silica that prevents the overgrowth of crystalline grains and the collapse of the mesoporosity. Using ilmenite CoTiO₃ as an example, the high crystallinity and the extraordinary thermal stability of its mesoporosity are demonstrated at 800 °C for 48 h under air. This synthetic approach is general and applicable to a series of complex oxides that are not reported with mesoporosity and high crystallinity, such as NiTiO₃, FeTiO₃, ZnTiO₃, Co₂TiO₄, Zn₂TiO₄, MgTi₂O₅, and FeTi₂O₅. Those novel materials make it possible to build up correlations between mesoscale porosity and surface‐sensitive physicochemical properties, e.g., electromagnetic response. For mesoporous CoTiO₃, there is a 3 K increase of its antiferromagnetic ordering temperature, compared with that of nonporous one. This finding provides a general guideline to design mesoporous complex oxides that allow exploring their unique properties different from bulk materials.     

Field‐Induced n‐Doping of Black Phosphorus for CMOS Compatible 2D Logic Electronics with High Electron Mobility

Black phosphorus (BP) has been considered as a promising two‐dimensional (2D) semiconductor beyond graphene owning to its tunable direct bandgap and high carrier mobility. However, the hole‐transport‐dominated characteristic limits the application of BP in versatile electronics. Here, we report a stable and complementary metal oxide semiconductor (COMS) compatible electron doping method for BP, which is realized with the strong field‐induced effect from the K⁺ center of the silicon nitride (Si_xN_y). An obvious change from pristine p‐type BP to n type is observed after the deposit of the Si_xN_y on the BP surface. This electron doping can be kept stable for over 1 month and capable of improving the electron mobility of BP towards as high as ~176 cm² V^–1 s^–1. Moreover, high‐performance in‐plane BP p‐n diode and further logic inverter were realized by utilizing the n‐doping approach. The BP p‐n diode exhibits a high rectifying ratio of ~10⁴. And, a successful transfer of the output voltage from “High” to “Low” with very few voltage loss at various working frequencies were also demonstrated with the constructed BP inverter. Our findings paves the way for the success of COMS compatible technique for BP‐based nanoelectronics.     

A Phase Transformation‐Resistant Electrode Enabled by a MnO2‐Confined Effect for Enhanced Energy Storage

Although the transition metal oxides/hydroxides are regarded as highly promising and attractive materials for efficient energy storage, a precycling/activation process is usually adopted to stabilize phase components and achieve reversible output. Moreover, the intrinsic mechanism involved in precycling process is not always concerned and remains to be further decoupled. Herein, overcoming the challenges associated with the MnO₂‐confined effect is proposed, which is enabled by in situ dissolving‐out and conversion of Mn species in MnO₂ derived from the Co‐induced effect. Notably, a high electrochemical stability without activation and a superior initial Coulombic efficiency of 96.2% can be achieved without any precycling or activation process, which increases by 33.5% in comparison to the efficiency of the hybrids without MnO₂ surface‐confined effect. And a specific capacity up to 164 mAh g^?1 at 2 A g^?1 can be achieved with an excellent capacity retention rate of 90% at 30 A g^?1, which only drops slightly and remains at a high level of 87% even after 5000 cycles. This strategy may function as a model for the design and configuration of highly stable electrodes toward high‐efficient energy storage and conversion applications.     

Photocatalyst Interface Engineering: Spatially Confined Growth of ZnFe2O4 within Graphene Networks as Excellent Visible‐Light‐Driven Photocatalysts

High‐performance photocatalysts should have highly crystallized nanocrystals (NCs) with small sizes, high separation efficiency of photogenerated electron–hole pairs, fast transport and consumption of photon‐excited electrons from the surface of catalyst, high adsorption of organic pollutant, and suitable band gap for maximally utilizing sunlight energy. However, the design and synthesis of these versatile structures still remain a big challenge. Here, we report a novel strategy for the synthesis of ultrasmall and highly crystallized graphene–ZnFe₂O₄ photocatalyst through interface engineering by using interconnected graphene network as barrier for spatially confined growth of ZnFe₂O₄, as transport channels for photon‐excited electron from the surface of catalyst, as well as the electron reservoir for suppressing the recombination of photogenerated electron–hole pairs. As a result, about 20 nm ZnFe₂O₄ NCs with highly crystallized (311) plane confined in the graphene network exhibit an excellent visible‐light‐driven photocatalytic activity with an ultrafast degradation rate of 1.924 × 10^?7 mol g^?1 s^?1 for methylene blue, much higher than those of previously reported photocatalysts such as spinel‐based photocatalysts (20 times), TiO₂‐based photocatalysts (4 times), and other photocatalysts (4 times). Our strategy can be further extended to fabricate other catalysts and electrode materials for supercapacitors and Li‐ion batteries.