Sulfur‐Modified Graphitic Carbon Nitride Nanostructures as an Efficient Electrocatalyst for Water Oxidation

There is an urgent need to develop metal‐free, low cost, durable, and highly efficient catalysts for industrially important oxygen evolution reactions. Inspired by natural geodes, unique melamine nanogeodes are successfully synthesized using hydrothermal process. Sulfur‐modified graphitic carbon nitride (S‐modified g‐CN _x ) electrocatalysts are obtained by annealing these melamine nanogeodes in situ with sulfur. The sulfur modification in the g‐CN _x structure leads to excellent oxygen evolution reaction activity by lowering the overpotential. Compared with the previously reported nonmetallic systems and well‐established metallic catalysts, the S‐modified g‐CN _x nanostructures show superior performance, requiring a lower overpotential (290 mV) to achieve a current density of 10 mA cm^?2 and a Tafel slope of 120 mV dec^?1 with long‐term durability of 91.2% retention for 18 h. These inexpensive, environmentally friendly, and easy‐to‐synthesize catalysts with extraordinary performance will have a high impact in the field of oxygen evolution reaction electrocatalysis.     

Carbon‐Supported Nickel Selenide Hollow Nanowires as Advanced Anode Materials for Sodium‐Ion Batteries

Carbon‐supported nickel selenide (Ni_0.85Se/C) hollow nanowires are prepared from carbon‐coated selenium nanowires via a self‐templating hydrothermal method, by first dissolving selenium in the Se/C nanowires in hydrazine, allowing it to diffuse out of the carbon layer, and then reacting with nickel ions into Ni_0.85Se nanoplates on the outer surface of the carbon. Ni_0.85Se/C hollow nanowires are employed as anode materials for sodium‐ion batteries, and their electrochemical performance is evaluated via the cyclic voltammetry and electrochemical impedance spectroscopy combined with ex situ X‐ray photoelectron spectroscopy and X‐ray diffraction measurements. It is found that Ni_0.85Se/C hollow nanowires exhibit greatly enhanced cycle stability and rate capability as compared to Ni_0.85Se nanoparticles, with a reversible capacity around 390 mA h g^?1 (the theoretical capacity is 416 mA h g^?1) at the rate of 0.2 C and 97% capacity retention after 100 cycles. When the current rate is raised to 5 C, they still deliver capacity of 219 mA h g^?1. The synthetic methodology introduced here is general and can easily be applied to building similar structures for other metal selenides in the future.     

Fluorination of CN x Nanotubes

Abstract

Multiwall CN _x nanotubes have been prepared by thermal decomposition of acetonitrile over Co/Ni catalytic particles. The fluorination of nanotubes was performed at room temperature by using a gaseous mixture of BrF₃ and Br₂. Transmission electron microscopy (TEM) and x‐ray diffraction (XRD) indicated that only the outer shells of CN _x nanotubes were fluorinated, whereas the inner shells remained intact. X‐ray photoelectron spectroscopy (XPS) showed an oxidation of pyridinic‐type nitrogen with tube fluorination.     

Hot‐Pressed CsPbBr3 Quasi‐Monocrystalline Film for Sensitive Direct X‐ray Detection

An X‐ray detector with high sensitivity would be able to increase the generated signal and reduce the dose rate; thus, this type of detector is beneficial for applications such as medical imaging and product inspection. The inorganic lead halide perovskite CsPbBr₃ possesses relatively larger density and a higher atomic number in contrast to its hybrid counterpart. Therefore, it is expected to provide high detection sensitivity for X‐rays; however, it has rarely been studied as a direct X‐ray detector. Here, a hot‐pressing method is employed to fabricate thick quasi‐monocrystalline CsPbBr₃ films, and a record sensitivity of 55 684 µC Gy_air^?1 cm^?2 is achieved, surpassing all other X‐ray detectors (direct and indirect). The hot‐pressing method is simple and produces thick quasi‐monocrystalline CsPbBr₃ films with uniform orientations. The high crystalline quality of the CsPbBr₃ films and the formation of self‐formed shallow bromide vacancy defects during the high‐temperature process result in a large µτ product and, therefore, a high photoconductivity gain factor and high detection sensitivity. The detectors also exhibit relatively fast response speed, negligible baseline drift, and good stability, making a CsPbBr₃ X‐ray detector extremely competitive for high‐contrast X‐ray detections.     

Characteristic and magnetic properties of Ni1–xZnxFe2O4 ferrites

Ferrites are magnetic ceramic materials which have additional metallic ion in ferrous oxide compounds. Ferrites are usually classified as soft or hard ferrites. In this study, characteristics and magnetic properties of magnetic materials having NiO_1–xZnO_xFe₂O₄ structure were investigated. Mechanical mixing of high purity NiO, ZnO and Fe₂O₃ powders were done to obtain homogenous NiO_1–xZnO_xFe₂O₄ powder mixture for x = 0.15, x = 0.50 and x = 0.85. These powder mixtures were pressed using hydraulic press machine and then subjected to sintering at same temperatures of 1000 °C for 1 hour. Obtained specimens were analyzed with scanning electron microscopy (SEM) imaging and energy dispersive X‐ray fluorescence (EDXRF) technique for the investigation of structural analysis; magnetic properties were determined using vibrating sample magnetometer (VSM). However, effects of composition, specimens and Zn% element in magnetic materials after energy dispersive X‐ray fluorescence on maximum magnetic moment (M_s) were analyzed using Taguchi orthogonal array design of experiments technique. The study indicates that Zn% element is the main process parameter that has the highest statistical influence on maximum magnetic moment. However, another parameter, composition, also has a significant effect on maximum magnetic moment. Then, Zn‐content was found to have a significant influence on the magnetic properties of the system.     

Investigation of Binary Metal (Ni,Co) Selenite as Li‐Ion Battery Anode Materials and Their Conversion Reaction Mechanism with Li Ions

Highly efficient anode materials with novel compositions for Li‐ion batteries are actively being researched. Multicomponent metal selenite is a promising candidate, capable of improving their electrochemical performance through the formation of metal oxide and selenide heterostructure nanocrystals during the first cycle. Here, the binary nickel–cobalt selenite derived from Ni–Co Prussian blue analogs (PBA) is chosen as the first target material: the Ni–Co PBA are selenized and partially oxidized in sequence, yielding (NiCo)SeO₃ phase with a small amount of metal selenate. The conversion mechanism of (NiCo)SeO₃ for Li‐ion storage is studied by cyclic voltammetry, in situ X‐ray diffraction, ex situ X‐ray photoelectron spectroscopy, in situ electrochemical impedance spectroscopy, and ex situ transmission electron microscopy. The reversible reaction mechanism of (NiCo)SeO₃ with the Li ions is described by the reaction: NiO + CoO + xSeO₂ + (1 ‐ x)Se + (4x + 6)Li⁺ + (4x + 6)e^? ? Ni + Co + (2x + 2)Li₂O + Li₂Se. To enhance electrochemical properties, polydopamine‐derived carbon is uniformly coated on (NiCo)SeO₃, resulting in excellent cycling and rate performances for Li‐ion storage. The discharge capacity of C‐coated (NiCo)SeO₃ is 680 mAh g^?1 for the 1500th cycle when cycled at a current density of 5 A g^?1.     

Preparation of the hard CNx thin films using NO ambient gas by pulsed laser deposition

Pulsed laser deposition (PLD) technique has been widely used in thin film preparation because of its wonderful and excellent properties and amorphous carbon nitride (CN_x) thin films are recognized to have potential for applications like hard coating and electron field emission device. We have deposited CN_x thin films by KrF excimer laser – (λ= 248 nm) ablation of pure graphite target in pure NO gas ambient condition. In this paper, we have prepared the CN_x thin films at various ambient NO gas pressure of 1.3–26 Pa and laser fluence of 2– 5J cm^?2 on Si (100) substrate. We consider that the hardness of CN_x thin films improves due to the increase the nitrogen/carbon (N/C) ratio. The N/C ratio depended on the ambient NO gas pressure and laser fluence. We obtainedthe maximum N/C ratio of 1.0 at NO 3.3 Pa. The typical absorption of CN bonds such as sp² C–N, sp³ C–N, G band and D band were detected from the infrared absorption measurement by FTIR in the deposited CN_x thin films.     

Manganese‐Based Na‐Rich Materials Boost Anionic Redox in High‐Performance Layered Cathodes for Sodium‐Ion Batteries

To improve the energy and power density of Na‐ion batteries, an increasing number of researchers have focused their attention on activation of the anionic redox process. Although several materials have been proposed, few studies have focused on the Na‐rich materials compared with Li‐rich materials. A key aspect is sufficient utilization of anionic species. Herein, a comprehensive study of Mn‐based Na_1.2Mn_0.4Ir_0.4O₂ (NMI) O3‐type Na‐rich materials is presented, which involves both cationic and anionic contributions during the redox process. The single‐cation redox step relies on the Mn³⁺/Mn⁴⁺, whereas Ir atoms build a strong covalent bond with O and effectively suppress the O₂ release. In situ Raman, ex situ X‐ray photoelectron spectroscopy, and soft‐X‐ray absorption spectroscopy are employed to unequivocally confirm the reversibility of O₂^2? species formation and suggest a high degree of anionic reaction in this NMI Na‐rich material. In operando X‐ray diffraction study discloses the asymmetric structure evolution between the initial and subsequent cycles, which also explains the effect of the charge compensation mechanism on the electrochemical performance. The research provides a novel insight on Na‐rich materials and a new perspective in materials design towards future applications.     

Hochstrom‐Filterbogen: eine neue Technik zur Abscheidung von Kohlenstoffschutzschichten in der Magnetspeichertechnologie. High Current Filtered Arc: a new Deposition Technique for Protecting Carbon Overcoats in Magnetic Storage Devices

Due to the lateral size reduction of stored bits on a hard disk, the head‐to‐media spacing has to be reduced as well as the thickness of the protecting carbon overcoats. In order to obtain a thickness in the 2 nm region a new process technology is needed. In the present paper, a high current pulsed arc (HCA) technique is presented as an innovative source for ultra thin carbon coating for future industrial disk production. The hardness and scratching resistance of these films are remarkable higher than conventional magnetron sputtered films. With the HCA‐Source we are able to produce pinhole‐free carbon films with thicknesses down to 2 nm. The deposition rate is 0.07 – 0.3 nm per pulse, therefore the coating time is below 2 sec per disk. The magnetic layer is left undamaged during the HCA deposition process. These aspects are very important for industrial disk production efficiency. Strong particle reduction due to a magnetic filter tube is confirmed by repeatable glide tests. Particles are confined in the magnetic filter tube and do not reach the substrate. In several important tests we showed that the HCA source is capable of producing carbon layers within a realistic disk production environment with a yield over 90 % which proved to be comparable to current magnetron sputtered overcoats.     

Teilkohärente Ausscheidungen in einer Eisen‐Chrom‐Kohlenstoff‐Legierung

Semicoherent precipitates in a Fe‐Cr‐C alloy Precipitation processes in ferromagnetic materials can be recorded very well by measuring the sensitive coercive field strength. It should be tested, whether also semicoherent precipitates have a sufficient clear interaction with Bloch‐walls. For this purpose the mild‐magnetic alloy X1FeCr25 served. To carry out the evidence sensitively, a method based on differences between H_C^t (heat‐treated state at T = 600…︁700°C) – H_C⁰ (quenched state from high temperature) = Δ H_C was used. A quantitative record of the amount of precipitates (as particle size) is possible by a decomposition parameter Δ H_C/Δ t. Plate‐like β′‐precipitates with planes {100}∥{100} in the α‐Fe solid solution have been proved by transmission electron microscopic investigations; this is the preparation state for the transition into the stable fcc phase M₂₃C₆. As a result, the quantitative electron microscopic proof of the β′‐phase can be supported by magnetic measurements, qualitatively and quantitatively. The estimated values of the activation energy for the process in the 1st maximum of precipitation in X1FeCr25 are higher than for the stable phases as the orthorhombic M₃C or the cubic complex M₆C in other steels and give a hint to the difficult processes related to nucleation as to the transition into M₂₃C₆.     

ZIF‐8/ZIF‐67‐Derived Co‐Nx‐Embedded 1D Porous Carbon Nanofibers with Graphitic Carbon‐Encased Co Nanoparticles as an Efficient Bifunctional Electrocatalyst

Herein, an approach is reported for fabrication of Co‐N_x‐embedded 1D porous carbon nanofibers (CNFs) with graphitic carbon‐encased Co nanoparticles originated from metal–organic frameworks (MOFs), which is further explored as a bifunctional electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Electrochemical results reveal that the electrocatalyst prepared by pyrolysis at 1000 °C (CoNC‐CNF‐1000) exhibits excellent catalytic activity toward ORR that favors the four‐electron ORR process and outstanding long‐term stability with 86% current retention after 40 000 s. Meanwhile, it also shows superior electrocatalytic activity toward OER, reaching a lower potential of 1.68 V at 10 mA cm^?2 and a potential gap of 0.88 V between the OER potential (at 10 mA cm^?2) and the ORR half‐wave potential. The ORR and OER performance of CoNC‐CNF‐1000 have outperformed commercial Pt/C and most nonprecious‐metal catalysts reported to date. The remarkable ORR and OER catalytic performance can be mainly attributable to the unique 1D structure, such as higher graphitization degree beneficial for electronic mobility, hierarchical porosity facilitating the mass transport, and highly dispersed CoN_xC active sites functionalized carbon framework. This strategy will shed light on the development of other MOF‐based carbon nanofibers for energy storage and electrochemical devices.     

Water adsorption on lubricated fullerene-like CNx films

Humidity influences the tribological performance of the head-disk interface in magnetic data storage devices. In this work we compare the uptake of water of amorphous hydrogenated carbon (a-CH_y) and carbon nitride (a-CN_x) films, widely used as protective overcoats in computer disk drive systems, with two types of amorphous non-hydrogenated carbon (a-C and a-C_sp²) films, and fullerene-like carbon nitride (FL-CN_x) films. Carbon films were deposited on quartz crystal substrates by reactive dc magnetron sputtering in Ar/N₂ discharges. After deposition, some of the films were coated with a 2-nm-thick layer of Z-tetraol, a lubricant used in hard disk devices. A quartz crystal microbalance placed in a vacuum chamber was used to measure the adsorption of water at room temperature and at pressures of water corresponding to relative humidities in the range RH = 0 to 90%. Water adsorption and desorption is fast, indicating that equilibrium with ambient humidity is reached on time scales of minutes, much faster than the time scales for fluctuations in ambient humidity. The amount of water adsorbed on the non-lubricated amorphous carbon films is significantly higher than that on the fullerene-like films. The presence of the lubricant influences water adsorption but its impact differs on different carbon films.     

Ramanspektroskopische Charakterisierung von ultra‐dünnen Kohlenstoff‐Schutzschichten für die Magnetspeichertechnologie

Raman‐spectroscopy is a standard tool for structural characterization of ultra‐thin (<10 nm) amorphous carbon films which are used as protective overcoats in the magnetic storage industry. It provides powerful information on the bonding structure of the films. The Raman‐spectra of amorphous carbons are dominated by the D‐ and G‐bands at around 1350 cm^‐1 – 1600 cm^‐1 whose position and intensity are used for interpreting the carbon bonding. Several carbon films have been investigated using green (λ = 514.5 nm) and ultraviolet (λ = 244 nm) laser‐light. The dispersion of the G‐peak is the most crucial of parameters to describe the internal structure of the films since it distinguishes between graphite‐ and diamond‐like carbon. A high G‐peak‐dispersion corresponds to a high sp³‐fraction. These information are not available by single wavelength investigations due to the so called hysteresis effect causing the Raman‐spectra of different samples accidentally to look similar albeit having a different internal structure. The dual‐method we are here introducing avoids the hysteresis effect and provides good estimations on the sp³‐content and the mass density of different carbon systems. Furthermore, UV‐Raman analysis leads to quantification of the nitrogen content of nitrogen‐doped carbon layers by using the relative intensity of the 2200 cm^‐1 band in the UV‐spectrum. The great advantage of ramanspectroscopic investigations is its celerity. Acquisition times are seldom higher than 1.5 min. Additionally, Raman‐spectroscopy is a non‐destructive tool which leaves the investigated samples undamaged for further processing and makes it an attractive method for insitu‐analysis in the magnetic storage industry.     

Exposing {010} Active Facets by Multiple‐Layer Oriented Stacking Nanosheets for High‐Performance Capacitive Sodium‐Ion Oxide Cathode

As one of the most promising cathodes for rechargeable sodium‐ion batteries (SIBs), O3‐type layered transition metal oxides commonly suffer from inevitably complicated phase transitions and sluggish kinetics. Here, a Na[Li_0.05Ni_0.3Mn_0.5Cu_0.1Mg_0.05]O₂ cathode material with the exposed {010} active facets by multiple‐layer oriented stacking nanosheets is presented. Owing to reasonable geometrical structure design and chemical substitution, the electrode delivers outstanding rate performance (71.8 mAh g^?1 and 16.9 kW kg^?1 at 50C), remarkable cycling stability (91.9% capacity retention after 600 cycles at 5C), and excellent compatibility with hard carbon anode. Based on the combined analyses of cyclic voltammograms, ex situ X‐ray absorption spectroscopy, and operando X‐ray diffraction, the reaction mechanisms behind the superior electrochemical performance are clearly articulated. Surprisingly, Ni²⁺/Ni³⁺ and Cu²⁺/Cu³⁺ redox couples are simultaneously involved in the charge compensation with a highly reversible O3–P3 phase transition during charge/discharge process and the Na⁺ storage is governed by a capacitive mechanism via quantitative kinetics analysis. This optimal bifunctional regulation strategy may offer new insights into the rational design of high‐performance cathode materials for SIBs.     

Flexible,Printable Soft‐X‐Ray Detectors Based on All‐Inorganic Perovskite Quantum Dots

Metal halide perovskites represent a family of the most promising materials for fascinating photovoltaic and photodetector applications due to their unique optoelectronic properties and much needed simple and low‐cost fabrication process. The high atomic number (Z) of their constituents and significantly higher carrier mobility also make perovskite semiconductors suitable for the detection of ionizing radiation. By taking advantage of that, the direct detection of soft‐X‐ray‐induced photocurrent is demonstrated in both rigid and flexible detectors based on all‐inorganic halide perovskite quantum dots (QDs) synthesized via a solution process. Utilizing a synchrotron soft‐X‐ray beamline, high sensitivities of up to 1450 µC Gy_air^?1 cm^?2 are achieved under an X‐ray dose rate of 0.0172 mGy_air s^?1 with only 0.1 V bias voltage, which is about 70‐fold more sensitive than conventional α‐Se devices. Furthermore, the perovskite film is printed homogeneously on various substrates by the inexpensive inkjet printing method to demonstrate large‐scale fabrication of arrays of multichannel detectors. These results suggest that the perovskite QDs are ideal candidates for the detection of soft X‐rays and for large‐area flat or flexible panels with tremendous application potential in multidimensional and different architectures imaging technologies.     

Atomic‐Level Fe‐N‐C Coupled with Fe3C‐Fe Nanocomposites in Carbon Matrixes as High‐Efficiency Bifunctional Oxygen Catalysts

Highly active and durable bifunctional oxygen electrocatalysts are of pivotal importance for clean and renewable energy conversion devices, but the lack of earth‐abundant electrocatalysts to improve the intrinsic sluggish kinetic process of oxygen reduction/evolution reactions (ORR/OER) is still a challenge. Fe‐N‐C catalysts with abundant natural merits are considered as promising alternatives to noble‐based catalysts, yet further improvements are urgently needed because of their poor stability and unclear catalytic mechanism. Here, an atomic‐level Fe‐N‐C electrocatalyst coupled with low crystalline Fe₃C‐Fe nanocomposite in 3D carbon matrix (Fe‐SAs/Fe₃C‐Fe@NC) is fabricated by a facile and scalable method. Versus atomically FeN_x species and crystallized Fe₃C‐Fe nanoparticles, Fe‐SAs/Fe₃C‐Fe@NC catalyst, abundant in vertical branched carbon nanotubes decorated on intertwined carbon nanofibers, exhibits high electrocatalytic activities and excellent stabilities both in ORR (E_1/2, 0.927 V) and OER (E_J=10, 1.57 V). This performance benefits from the strong synergistic effects of multicomponents and the unique structural advantages. In‐depth X‐ray absorption fine structure analysis and density functional theory calculation further demonstrate that more extra charges derived from modified Fe clusters decisively promote the ORR/OER performance for atomically FeN₄ configurations by enhanced oxygen adsorption energy. These insightful findings inspire new perspectives for the rational design and synthesis of economical–practical bifunctional oxygen electrocatalysts.     

Multifunctional Yolk‐in‐Shell Nanoparticles for pH‐triggered Drug Release and Imaging

Multifunctional nanoparticles are synthesized for both pH‐triggered drug release and imaging with radioluminescence, upconversion luminescent, and magnetic resonance imaging (MRI). The particles have a yolk‐in‐shell morphology, with a radioluminescent core, an upconverting shell, and a hollow region between the core and shell for loading drugs. They are synthesized by controlled encapsulation of a radioluminescent nanophosphor yolk in a silica shell, partial etching of the yolk in acid, and encapsulation of the silica with an upconverting luminescent shell. Metroxantrone, a chemotherapy drug, was loaded into the hollow space between X‐ray phosphor yolk and up‐conversion phosphor shell through pores in the shell. To encapsulate the drug and control the release rate, the nanoparticles are coated with pH‐responsive biocompatible polyelectrolyte layers of charged hyaluronic acid sodium salt and chitosan. The nanophosphors display bright luminescence under X‐ray, blue light (480 nm), and near infrared light (980 nm). They also served as T₁ and T₂ MRI contrast agents with relaxivities of 3.5 mM^?1 s^?1 (r₁) and 64 mM^?1s^?1 (r₂). These multifunctional nanocapsules have applications in controlled drug delivery and multimodal imaging.     

Oxidizing Vacancies in Nitrogen‐Doped Carbon Enhance Air‐Cathode Activity

Oxidizing vacancies in nitrogen‐doped carbon have recently been reported to enhance the oxygen reaction activity of air cathodes, but their specific role has remained elusive and controversial. Herein, the critical role of oxidizing the vacancies in enhancing the oxygen reduction reaction for metal–air battery is identified with density functional theory. Deliberate introduction of oxygen‐enriched vacancies in nitrogen‐doped carbon is shown experimentally to provide superior oxygen reduction activity. In situ X‐ray powder diffraction gives direct observation of the oxygen reactions in a zinc–air battery catalyzed by vacancy‐enriched oxidized carbon; the intensity changes of the carbon peak show continuous chemisorption of oxygen intermediates on the carbon cathode during discharge. The air‐cathode performance is shown to exceed that with Pt/C+IrO₂ catalysts.     

Metal–Carbon Hybrid Electrocatalysts Derived from Ion‐Exchange Resin Containing Heavy Metals for Efficient Hydrogen Evolution Reaction

Transition metal–carbon hybrids have been proposed as efficient electrocatalysts for hydrogen evolution reaction (HER) in acidic media. Herein, effective HER electrocatalysts based on metal–carbon composites are prepared by controlled pyrolysis of resin containing a variety of heavy metals. For the first time, Cr₂O₃ nanoparticles of 3–6 nm in diameter homogeneously dispersed in the resulting porous carbon framework (Cr–C hybrid) is synthesized as efficient HER electrocatalyst. Electrochemical measurements show that Cr–C hybrids display a high HER activity with an onset potential of ?49 mV (vs reversible hydrogen electrode), a Tafel slope of 90 mV dec^?1, a large catalytic current density of 10 mA cm^?2 at ?123 mV, and the prominent electrochemical durability. X‐ray photoelectron spectroscopic measurements confirm that electron transfer occurs from Cr₂O₃ into carbon, which is consistent with the reported metal@carbon systems. The obtained correlation between metals and HER activities may be exploited as a rational guideline in the design and engineering of HER electrocatalysts.     

Ti‐Substituted NaNi0.5Mn0.5‐xTixO2 Cathodes with Reversible O3−P3 Phase Transition for High‐Performance Sodium‐Ion Batteries

Sodium‐ion batteries (SIBs) have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. O3‐type layered oxides have been considered as one of the most promising cathodes for SIBs. However, they commonly show inevitable complicated phase transitions and sluggish kinetics, incurring rapid capacity decline and poor rate capability. Here, a series of sodium‐sufficient O3‐type NaNi_0.5Mn_{0.5‐ x} Ti _x O₂ (0 ≤ x ≤ 0.5) cathodes for SIBs is reported and the mechanisms behind their excellent electrochemical performance are studied in comparison to those of their respective end‐members. The combined analysis of in situ X‐ray diffraction, ex situ X‐ray absorption spectroscopy, and scanning transmission electron microscopy for NaNi_0.5Mn_0.2Ti_0.3O₂ reveals that the O3‐type phase transforms reversibly into a P3‐type phase upon Na+ deintercalation/intercalation. The substitution of Ti for Mn enlarges interslab distance and could restrain the unfavorable and irreversible multiphase transformation in the high voltage regions that is usually observed in O3‐type NaNi_0.5Mn_0.5O₂, resulting in improved Na cell performance. This integration of macroscale and atomicscale engineering strategy might open up the modulation of the chemical and physical properties in layered oxides and grasp new insight into the optimal design of high‐performance cathode materials for SIBs.