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Lithium–sulfur (Li–S) batteries are receiving great attention owing to their large theoretical energy density, but the shuttle effect and sluggish kinetic conversion of lithium polysulfides (LiPSs) seriously restrict their practical applications. Herein, various metal single‐atom catalysts immobilized on nitrogen‐doped Ti3C2Tx (M SA/N‐Ti3C2Tx, M = Cu, Co, Ni, Mn, Zn, In, Sn, Pb, and Bi) are successfully prepared by a neoteric vacancy‐assisted strategy, applied as polypropylene (PP) separator coatings to facilitate the fast redox conversion and adsorption of LiPSs for boosting Li–S batteries. Of particular note, among the M SA/N‐Ti3C2Txs, Cu SA/N‐Ti3C2Tx/PP exhibits amazing properties, involving excellent rate performance (925 mAh g−1 at 3 C), superb cycling stability over 1000 cycles, and ultra‐high sulfur utilization even at large sulfur loadings (7.19 mg cm−2; an areal capacity of 5.28 mAh cm−2). X‐ray absorption fine spectroscopy and density functional theory calculations reveal that the asymmetrically coordinated Cu–N1C2 moieties act as the active sites, which possess a higher binding energy and a larger electron cloud with LiPSs than pristine Ti3C2Tx, facilitating the adsorption and kinetic conversion of LiPSs effectively. This work may provide new insights into single atom‐decorated ultrathin 2D materials for enhancing electrochemical performance of advanced batteries for energy storage and conversion. [ABSTRACT FROM AUTHOR]

The development of inexpensive and highly efficient nonprecious metal catalysts to substitute Pt in the alkaline oxygen reduction reaction is an appealing idea in the energy field. Herein, a Mn oxygen reduction electrocatalyst with a half‐wave potential (E1/2) as high as 0.910 V under an alkaline oxygen reduction reaction process is developed, and the dynamic atomic structure change of the highly efficient Mn single‐atomic site is investigated using operando X‐ray absorption spectroscopy. These results demonstrate that the low‐valence MnL+N4 is the active site during the oxygen reduction process. Density functional theory reveals that facile electron transfer from MnL+N4 to adsorbed *OH species plays a key role in the excellent electrocatalytic performance. Moreover, when assembled as the cathode in a zinc–air battery, this MnN4 material shows high power density and excellent durability, demonstrating its promising potential to substitute the Pt catalyst in practical devices. [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) nanosheets show good activity in a wide range of photoreactions, with this activity being generally attributable to an abundance of surface oxygen vacancies or coordinatively unsaturated metal cations in the nanosheets which serve as active sites for reactant adsorption and activation. Recently, LDH nanosheets have been shown to be very effective for photocatalytic N2 reduction to NH3 using water as the reducing agent. Herein, it is demonstrated that a simple pretreatment of ZnCr‐LDH, ZnAl‐LDH, and NiAl‐LDH nanosheets with aqueous NaOH can greatly enhance the concentration of oxygen vacancies and low coordination metal centers in the nanosheets, thus significantly enhancing their photocatalytic activity for N2 reduction to NH3 under UV–vis irradiation (without the need for added sacrificial agents or cocatalysts). The facile alkali etching strategy introduced here is expected to be widely adopted in the future development of high‐performance LDH photocatalysts for ammonia production and other challenging chemical transformations (e.g., CO2 reduction and water splitting). [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) nanosheets show good activity in a wide range of photoreactions, with this activity being generally attributable to an abundance of surface oxygen vacancies or coordinatively unsaturated metal cations in the nanosheets which serve as active sites for reactant adsorption and activation. Recently, LDH nanosheets have been shown to be very effective for photocatalytic N2 reduction to NH3 using water as the reducing agent. Herein, it is demonstrated that a simple pretreatment of ZnCr‐LDH, ZnAl‐LDH, and NiAl‐LDH nanosheets with aqueous NaOH can greatly enhance the concentration of oxygen vacancies and low coordination metal centers in the nanosheets, thus significantly enhancing their photocatalytic activity for N2 reduction to NH3 under UV–vis irradiation (without the need for added sacrificial agents or cocatalysts). The facile alkali etching strategy introduced here is expected to be widely adopted in the future development of high‐performance LDH photocatalysts for ammonia production and other challenging chemical transformations (e.g., CO2 reduction and water splitting). [ABSTRACT FROM AUTHOR]

Abstract: The exploration of new and efficient energy storage mechanisms through nanostructured electrode design is crucial for the development of high‐performance rechargeable batteries. Herein, black phosphorus quantum dots (BPQDs) and Ti3C2 nanosheets (TNSs) are employed as battery and pseudocapacitive components, respectively, to construct BPQD/TNS composite anodes with a novel battery‐capacitive dual‐model energy storage (DMES) mechanism for lithium‐ion and sodium‐ion batteries. Specifically, as a battery‐type component, BPQDs anchored on the TNSs are endowed with improved conductivity and relieved stress upon cycling, enabling a high‐capacity and stable energy storage. Meanwhile, the pseudocapacitive TNS component with further atomic charge polarization induced by POTi interfacial bonds between the two components allows enhanced charge adsorption and efficient interfacial electron transfer, contributing a higher pseudocapacitive value and fast energy storage. The DMES mechanism is evidenced by substantial characterizations of X‐ray photoelectron spectroscopy and X‐ray absorption fine structure spectroscopy, density functional theory calculations, and kinetics analyses. Consequently, the composite electrode exhibits superior battery performance, especially for lithium storage, such as high capacity (910 mAh g−1 at 100 mA g−1), long cycling stability (2400 cycles with a capacity retention over 100%), and high rate capability, representing the best comprehensive battery performance in BP‐based anodes to date. [ABSTRACT FROM AUTHOR]

Nonprecious metal catalysts (NPMCs) FeNC are promising alternatives to noble metal Pt as the oxygen reduction reaction (ORR) catalysts for proton-exchange-membrane fuel cells. Herein, a new modulation strategy is reported to the active moiety FeN4 via a precise 'single-atom to single-atom' grafting of a Pt atom onto the Fe center through a bridging oxygen molecule, creating a new active moiety of Pt1O2Fe1N4. The modulated FeNC exhibits remarkably improved ORR stabilities in acidic media. Moreover, it shows unexpectedly high catalytic activities toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), with overpotentials of 310 mV for OER in alkaline solution and 60 mV for HER in acidic media at a current density of 10 mA cm−2, outperforming the benchmark RuO2 and comparable with Pt/C(20%), respectively. The enhanced multifunctional electrocatalytic properties are associated with the newly constructed active moiety Pt1O2Fe1N4, which protects Fe sites from harmful species. Density functional theory calculations reveal the synergy in the new active moiety, which promotes the proton adsorption and reduction kinetics. In addition, the grafted Pt1O2 dangling bonds may boost the OER activity. This study paves a new way to improve and extend NPMCs electrocatalytic properties through a precisely single-atom to single-atom grafting strategy. [ABSTRACT FROM AUTHOR]

Energy‐saving and value‐added management in advanced catalysis is highly desirable but is challenged by the limitations of multifunctional catalysts and catalytic modules. Herein, an azo‐linked phthalocyanine‐porphyrin covalent organic framework (COF) with the ultrathin layered nanostructure grown on carbon nanotubes (NiPc‐azo‐H2Pp@CNTs) has been designed and synthesized, which can serve as a highly active and stable bifunctional heterojunction electrocatalyst for selective paired‐electrosynthesis through coupling anodic iodide oxidation reaction and cathodic CO2 conversion. Particularly, the inbuilt local microenvironment conferred by the dihydroporphyrin moieties in COF can act as a proton reservoir to promote the proton relay at the heterojunction interface during the electrocatalytic process. Moreover, through the cascade construction of dual electrocatalytic/organocatalytic modules, the cathode‐generated CO can be further converted to dimethyl carbonate with a yield of 6.21 mmol L−1 h−1, while the anode‐produced iodine can be derived into iodoform on the hundred‐milligram scale. It is worth noting that the value‐added cascade synthesis mediated by paired‐electrolysis using the distinctive and high‐powered electrocatalysts will help advance the sustainable development of industrial intelligent manufacturing. [ABSTRACT FROM AUTHOR]