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Calcium ion batteries (CIBs) are considered as an important candidate for post‐lithium energy storage devices due to their abundance of resources and low cost. However, CIBs still suffer from slow kinetics due to the large solvation structure and high desolvation energy of Ca2+ ions. Here, a solvation regulation strategy based on donor number (DN) is reported to achieve easy‐desolvation and rapid storage of Ca2+ in sodium vanadate (Na2V6O16·2H2O, NVO). Specially, the solvent with a low DN, represented by propylene carbonate (PC), forms the first solvation shell of calcium ions with weak binding energy and small shell structure, which facilitates the migration of Ca2+ in the electrolyte. More importantly, the low DN solvent is preferentially desolvated at the cathode/electrolyte interface, promoting the insertion of Ca2+ into the NVO electrode. Mechanism studies further confirm the highly reversible uptake/release of Ca2+ in the NVO cathode, along with the VO distance change in the coordination structure. Therefore, the NVO cathode achieves high capacity (376 mAh g−1 at 0.3 A g−1) and high‐rate performance (151 mAh g−1 at 5 A g−1). The weak solvation effect strategy further improves the electrochemical performance and provides great importance for the design of the long‐term development of CIBs. [ABSTRACT FROM AUTHOR]

Vanadate materials are feasible cathodes for metal–ion batteries due to their stable layered structure, abundant valence states, and high capacity. However, much uncertainty still exists about precisely modulating intercalants to facilitate ion storage. Here, V2O5 pre‐intercalated with various transition metal ions M2+ (M═Ni, Co, Mn) are developed as model materials to analyze the coupling effect between guest ions and host material. Through density functional theory simulations, it is found that M2+ interacts with V–O chain via M 3d‐O 2p covalent bonds, and extended X‐ray absorption fine structure reveals the Ni─O interatomic distance at 1.56 Å shorter than Co─O (1.60 Å) and Mn─O (1.72 Å), suggesting the M–O band type with different covalency degree can optimize VOx polyhedron and local electronic structure. Furthermore, NiVO cathode materials with the smallest layer spacing shows higher redox voltage and better rate/cycling performance for Ca2+ storage than CoVO/MnVO, elucidating that Ni has stronger tendency to attract electrons and bonds with V–O layer tightly, thus supplying a reliable ion diffusion channel for Ca2+. Through ions pre‐intercalated techniques, this work highlights both layer spacing and physicochemical properties of intercalants affect electrochemical process, which is significant for developing high‐performance vanadate cathode materials. [ABSTRACT FROM AUTHOR]

Exploring efficient transition-metal-based electrocatalysts for oxygen evolution reaction (OER) is imperative but remain challenging for sustainable energy storage and conversion systems. Foreign species doping is a significant regulation strategy to enhance the intrinsic activity of host matrix. However, the potential relationship of structure-activity caused by guest doping elements is seldom tracked systematically. In this case, both theoretical screening and experimental verification are complementarily employed to investigate the guest doping effects of ten first-row transition metals (Sc~Zn) on bimetallic NiCo layered double hydroxide (NiCo-LDH). As a result, the optimized Fe-doped NiCo-LDH is identified as the most promising candidate toward alkaline electrocatalytic OER, which exhibits the quasi-industrial current density of 1000 mA cm-2 at overpotential of400 mV. Meanwhile, it also shows impressively long-term stability of 500 h at 500 mA cm-2 with a negligible activity loss. Moreover, in situ electrochemical Raman spectroscopy unveils the dynamic structure evolution from pre-catalytic state (Fe-NiCo-LDH) to metal oxyhydroxide (Fe-(NiCo)OOH) during the oxidation reaction, and ab-initio molecular dynamics simulations are further performed to confirm the thermodynamic stability of activated Fe-(NiCo)OOH phase. This work provides a promising platform for exploring the critical role of transition metal guest doping on host matrix in developing industrially required OER electrocatalysts. [ABSTRACT FROM AUTHOR]

The intrinsic poor structural and thermal stability of high‐voltage layered cathodes are aggravated as the charging depth increases, which severely threatens the cycle life and safety of the battery. Herein, without modifying the high‐voltage layered cathode itself, a simple and economic blending strategy is introduced, and an olivine‐LiCoO2 blended cathode featuring superior comprehensive performance (energy, power, cycle‐life, and safety) at 4.65 V is fabricated. The strong bonding affinity at the olivine/LiCoO2 contact interface suppresses lattice O2 release of LiCoO2, thus significantly improving the structural and thermal stability at high delithiation states. Meanwhile, by contacting with high‐electron‐conductivity LiCoO2, the redox activity of olivine is further activated. Therefore, a stable operation of both olivine‐LiCoO2 and olivine‐LiNi0.8Co0.1Mn0.1O2 blended cathode is achieved under harsh cycling conditions (high voltage or elevated temperature) and long‐life pouch‐cell (91.6% capacity retention after 1000 cycles) is harvested, demonstrating the feasibility and universality of this economic blending strategy on heterogenous cathode candidates. [ABSTRACT FROM AUTHOR]

Photocatalytic CO2 reduction (CO2PR) into multi‐carbon products (especially C2H4) is a highly attractive route for global carbon cycle, however, which is seriously limited by sluggish C‐C coupling kinetics and competitive hydrogen evolution reaction (HER) and so on. Herein, the fabrication of a novel supramolecular assembly of NiAl‐Fe‐TCPP is reported by intercalating iron porphyrin (Fe‐TCPP) into NiAl‐layered double hydroxide (NiAl‐LDH), and the resultant NiAl‐Fe‐TCPP exhibit superior catalytic performance on CO2PR to C2H4 under visible light irradiation in presence of photosensitizer. A high C2H4 selectivity up to 93.4% in the carbon‐containing products with the production rate as high as 24.7 µmol h−1 can be achieved over NiAl‐Fe‐TCPP. The ex/in situ X–ray absorption spectoscopy (XAS) indicates that the electron transfer between NiAl‐LDH and Fe‐TCPP can promote the generation of low‐valence of Fe sites, resulting in the efficient production of C2H4. The spin‐polarized density functional theory (DFT) calculations find that the synergistic mechanism that CO2 molecules are activated to CO on NiAl‐LDH and then spilled to Fe‐TCPP and coupled to COCHO#, which is further reduced to C2H4, are feasible in the perspective of Gibbs free energy. Moreover, the strong host‐guest interactions between NiAl‐LDH and Fe‐TCPP lead to the promoted photocatalytic activity and superior cycle stability. [ABSTRACT FROM AUTHOR]

Regulating the coordination environment via heteroatoms to break the symmetrical electronic structure of M‐N4 active sites provides a promising route to engineer metal‐nitrogen‐carbon catalysts for electrochemical CO2 reduction reaction. However, it remains challenging to realize a site‐specific introduction of heteroatoms at atomic level due to their energetically unstable nature. Here, this paper reports a facile route via using an oxygen‐ and nitrogen‐rich metal–organic framework (MOF) (IRMOF‐3) as the precursor to construct the Fe‐O and Fe‐N chelation, simultaneously, resulting in an atomically dispersed axial O‐coordinated FeN4 active site. Compared to the FeN4 active sites without O coordination, the formed FeN4‐O sites exhibit much better catalytic performance toward CO, reaching a maximum FECO of 95% at −0.50 V versus reversible hydrogen electrode. To the best of the authors' knowledge, such performance exceeds that of the existing Fe‐N‐C‐based catalysts derived from sole N‐rich MOFs. Density functional theory calculations indicate that the axial O‐coordination regulates the binding energy of intermediates in the reaction pathways, resulting in a smoother desorption of CO and increased energy for the competitive hydrogen production. [ABSTRACT FROM AUTHOR]

Electrochemical synthesis of NH3 is a carbon‐free alternative to the traditional Haber–Bosch process. Obtaining NH3 from environmental pollutants, such as nitrates or nitrites, is a more practical route than from the nitrogen reduction reaction (NRR) due to the difficult cleavage of the inert triple bond of nitrogen gas. Here, a novel heterogeneous catalyst is reported based on iron (Fe) single‐atoms supported on 2D MoS2 (Fe‐MoS2) for the nitrate reduction reaction (NO3RR). Fe‐MoS2 exhibits remarkable performance with a maximum Faradaic efficiency of 98% for NO3RR to NH3 at an onset potential of −0.48 V versus the reversible hydrogen electrode (RHE) as confirmed by the isotopic nuclear magnetic resonance (NMR) analyses. Density functional theory (DFT) calculations reveal that the enhanced selectivity for the production of NH3 from single Fe atoms supported on MoS2 is attributed to a reduced energy barrier of 0.38 eV associated with de‐oxidation of *NO to *N. The catalysts are coupled to an InGaP/GaAs/Ge triple‐junction solar cell to demonstrate a solar‐to‐ammonia (STA) conversion efficiency of 3.4% and a yield rate of 510 µg h−1 cm−2. The results open new avenues for the design of single‐atom catalysts (SAC) for the realization of solar‐driven ammonia production. [ABSTRACT FROM AUTHOR]

Developing single‐atom electrocatalysts with high activity and superior selectivity at a wide potential window for CO2 reduction reaction (CO2RR) still remains a great challenge. Herein, a porous NiNC catalyst containing atomically dispersed NiN4 sites and nanostructured zirconium oxide (ZrO2@Ni‐NC) synthesized via a post‐synthetic coordination coupling carbonization strategy is reported. The as‐prepared ZrO2@Ni‐NC exhibits an initial potential of −0.3 V, maximum CO Faradaic efficiency (F.E.) of 98.6% ± 1.3, and a low Tafel slope of 71.7 mV dec−1 in electrochemical CO2RR. In particular, a wide potential window from −0.7 to −1.4 V with CO F.E. of above 90% on ZrO2@Ni‐NC far exceeds those of recently developed state‐of‐the‐art CO2RR electrocatalysts based on NiN moieties anchored carbon. In a flow cell, ZrO2@Ni‐NC delivers a current density of 200 mA cm−2 with a superior CO selectivity of 96.8% at −1.58 V in a practical scale. A series of designed experiments and structural analyses identify that the isolated NiN4 species act as real active sites to drive the CO2RR reaction and that the nanostructured ZrO2 largely accelerates the protonation process of *CO2− to *COOH intermediate, thus significantly reducing the energy barrier of this rate‐determining step and boosting whole catalytic performance. [ABSTRACT FROM AUTHOR]

Solar‐to‐Ammonia Efficiency In article 2108316, Damien Voiry and co‐workers report a single atom catalyst based on iron single atoms supported on 2D MoS2 nanosheets. The catalyst demonstrates near‐unity selectivity for the electrosynthesis of ammonia with a solar‐to‐NH3 efficiency of 3.4% when coupled to an external InGaP/GaAs/Ge triple‐junction solar cell. [ABSTRACT FROM AUTHOR]

The electrooxidation of urea holds great potential for converting urea from wastewater into hydrogen, contributing to environmental protection and sustainable energy production. This necessitates the development of highly efficient and stable catalysts for the urea oxidation reaction (UOR). In this study, a NiCoCr‐LDH/NF (nickel‐cobalt‐chromium layered double hydroxide/nickel foam) electrode is successfully synthesized via a simple hydrothermal method, demonstrating excellent electrocatalytic performance with a low work potential of 1.38 V at a high current density of 100 mA cm−2. In situ, Raman spectra analysis revealed that the incorporation of chromium (Cr) facilitated the generation of active γ‐NiOOH species and catalyst reconstruction. Density functional theory (DFT) simulations confirmed that the lower formation energy of γ‐NiOOH is due to the weakened interaction of O─H bonds because of a narrow energy range of hybridization between O‐2pz orbitals and H‐1s orbitals. The introduction of Cr also improved the adsorption energy of urea molecules and its intermediates, thereby enhancing the overall activity of UOR. With its excellent electrocatalytic performance, unique electronic states, and coordination structures, the NiCoCr‐LDH/NF electrode showcases great potential for practical applications in the field of energy catalysis. [ABSTRACT FROM AUTHOR]

Chloride ion batteries (CIBs) are a promising type of energy storage device due to their high theoretical volumetric energy density and abundant reserves of chlorine‐containing precursors. However, the unsatisfactory cycling performance and structural instability of cathode materials hinder their practical application. In this work, layered double hydroxides (LDHs), which consist of a trimetallic NiVAl hydroxide host matrix and interlayer Cl−, are demonstrated to be high‐performance cathode materials for CIBs. The Ni2V0.9Al0.1‐Cl LDH is capable of delivering a high initial capacity of 312.2 mAh g−1 at 200 mA g−1 and an ultralong life over 1000 cycles (with a capacity higher than 113.8 mAh g−1). Such a long cycling life exceeds that of any reported CIBs. The remarkable Cl−‐storage performance of the Ni2V0.9Al0.1‐Cl LDH is ascribed to the synergetic contributions from Vm+ (high redox activity), Ni2+ (favorable electronic structure), and inactive Al3+ (enhances the structural stability), which is revealed by a comprehensive study that utilizes synchrotron X‐ray absorption near‐edge structure experiments, kinetic investigations, and theoretical calculations. This study provides an effective strategy to achieve superior rechargeable batteries, which are applicable to large‐scale energy storage and power grids. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide reduction reaction (CO2RR) provides a promising pathway for both decreasing atmospheric CO2 concentration and producing valuable carbon‐based fuels. To explore efficient and cost‐effective catalysts for electrochemical CO2RR is of great importance, but remains challenging. Se‐doped carbon nanosheets (Se‐CNs) with a micro‐, meso‐, and macroporous structure are proposed for electrochemical CO2RR. Such an electrocatalyst combines the advantages of Se optimized active sites, hierarchical pores for facilitating reactant or ion penetration, transport and reaction, and large surface area for more accessible active sites. This Se‐CNs electrocatalyst exhibits over 11‐times enhanced partial current density of CO than the CNs without Se doping and high selectivity (90%) for CO2 electroreduction to CO at a low potential of −0.6 V versus the reversible hydrogen electrode (vs RHE). Density function theoretical calculations reveal that the Se introduction in CNs lowers the free energy barrier of CO2RR and inhibits hydrogen evolution reaction effectively, thus improving the selectivity for CO2 reduction to CO. This work presents a new member of the metal‐free electrocatalyst family, which is easily prepared, low cost, adjustable, and highly efficient for CO2RR. [ABSTRACT FROM AUTHOR]

Dielectric materials are greatly desired for electromagnetic absorption applications. Lots of research shows that conduction loss and polarization are two of the most important factors determining complex permittivity. However, the detailed dissipation mechanisms for the improved microwave absorption performance are often based on semiempirical rules, lacking practical data relationships between conduction loss/polarization and dielectric behaviors. Here, a strategy of introducing point defects is used to understand such underlying relationships, where polarizability and conductivity are adjustable by manipulating oxygen deficiency or heteroatoms. Based on first principles calculations and the applied oxygen‐deficient strategy, dielectric polarization is shown to be dominant in determining the permittivity behaviors in semiconductors. Meanwhile, the presented nitrogen doping strategy shows that conduction loss is dominant in determining the permittivity behavior in graphitized carbon materials. The validity of the methods for using point defects to explore the underlying relations between conduction loss/polarization and dielectric behaviors in semiconductor and graphitized carbon are demonstrated for the first time, which are of great importance in optimizing the microwave absorption performance by defect engineering and electronic structure tailoring. [ABSTRACT FROM AUTHOR]

Lead halide perovskites have demonstrated outstanding achievements in photoelectric applications owing to their unique properties. However, the moisture sensitivity of lead halide perovskite has rarely been developed into an applicable humidity sensor due to the intrinsic instability and toxicity issue. Herein, as a highly stable lead‐free perovskite, a Cs2BiAgBr6 thin film is chosen to be the active material for humidity sensor due to its extraordinary humidity‐dependent electrical properties and good stability. This Cs2BiAgBr6 thin film humidity sensor demonstrates a superfast response time (1.78 s) and recovery time (0.45 s). The superfast response and recovery properties can be attributed to the reversible physisorption of water molecules, which can be easily adsorbed onto or desorbed from the thin film surface. Moreover, the sensor also shows an excellent reliability and stability properties as well as logarithmic linearity in a relative humidity's range of 15% to 78%. The lead‐free Cs2BiAgBr6 perovskite possesses great potential for application in real‐time humidity sensing. [ABSTRACT FROM AUTHOR]

Herein, an example of Cu‐doped few‐layer ZnIn2S4 nanosheets is used to reveal the origin of optimum and excess doping for photocatalysts at atomic level. Results show that the metal‐S4 coordination maintains well with 0.5 wt% Cu substituted Zn atoms in the lattice. The introduced Cu atoms bring electronic acceptor states close to the valence band (VB) maximum and thus ensures higher charge density and efficient carrier transport, resulting in an optimum hydrogen evolution rate of 26.2 mmol h−1 g−1 and an apparent quantum efficiency of 4.76% at 420 nm. However, a distorted atomic structure and largely upshift of VB maximum with Cu‐S3.6 coordination are found with excess doping concentration (3.6 wt%). These bring the heavy charge recombination and consequentially dramatic reduced activity. This work provides a new insight into elemental doping study and takes an important step toward the development of ultrathin 2D photocatalysts. Few‐layer ZnIn2S4 nanosheets with tunable copper doping are used to disclose the origin of optimum and excess doping for photocatalysis at atomic level. Experimental and theoretical evidence reveal that optimal and excess doping is derived from the different local coordination configuration of dopants, extent of distortion, and the change of electronic structure. [ABSTRACT FROM AUTHOR]

The intrinsic poor structural and thermal stability of high‐voltage layered cathodes are aggravated as the charging depth increases, which severely threatens the cycle life and safety of the battery. Herein, without modifying the high‐voltage layered cathode itself, a simple and economic blending strategy is introduced, and an olivine‐LiCoO2 blended cathode featuring superior comprehensive performance (energy, power, cycle‐life, and safety) at 4.65 V is fabricated. The strong bonding affinity at the olivine/LiCoO2 contact interface suppresses lattice O2 release of LiCoO2, thus significantly improving the structural and thermal stability at high delithiation states. Meanwhile, by contacting with high‐electron‐conductivity LiCoO2, the redox activity of olivine is further activated. Therefore, a stable operation of both olivine‐LiCoO2 and olivine‐LiNi0.8Co0.1Mn0.1O2 blended cathode is achieved under harsh cycling conditions (high voltage or elevated temperature) and long‐life pouch‐cell (91.6% capacity retention after 1000 cycles) is harvested, demonstrating the feasibility and universality of this economic blending strategy on heterogenous cathode candidates. [ABSTRACT FROM AUTHOR]

Herein, an example of Cu‐doped few‐layer ZnIn2S4 nanosheets is used to reveal the origin of optimum and excess doping for photocatalysts at atomic level. Results show that the metal‐S4 coordination maintains well with 0.5 wt% Cu substituted Zn atoms in the lattice. The introduced Cu atoms bring electronic acceptor states close to the valence band (VB) maximum and thus ensures higher charge density and efficient carrier transport, resulting in an optimum hydrogen evolution rate of 26.2 mmol h−1 g−1 and an apparent quantum efficiency of 4.76% at 420 nm. However, a distorted atomic structure and largely upshift of VB maximum with Cu‐S3.6 coordination are found with excess doping concentration (3.6 wt%). These bring the heavy charge recombination and consequentially dramatic reduced activity. This work provides a new insight into elemental doping study and takes an important step toward the development of ultrathin 2D photocatalysts. Few‐layer ZnIn2S4 nanosheets with tunable copper doping are used to disclose the origin of optimum and excess doping for photocatalysis at atomic level. Experimental and theoretical evidence reveal that optimal and excess doping is derived from the different local coordination configuration of dopants, extent of distortion, and the change of electronic structure. [ABSTRACT FROM AUTHOR]