Regulating Electron Filling and Orbital Occupancy of Anti-Bonding States of Transition Metal Nitride Heterojunction for High Areal Capacity Lithium-Sulfur Full Batteries.

The commercialization of lithium-sulfur (Li-S) battery is seriously hindered by the shuttle behavior of lithium (Li) polysulfide, slow conversion kinetics, and Li dendrite growth. Herein, a novel hierarchical p-type iron nitride and n-type vanadium nitride (p-Fe2 N/n-VN) heterostructure with optimal electronic structure, confined in vesicle-like N-doped nanofibers (p-Fe2 N/n-VN⊂PNCF), is meticulously constructed to work as "one stone two birds" dual-functional hosts for both the sulfur cathode and Li anode. As demonstrated, the d-band center of high-spin Fe atom captures more electrons from V atom to realize more π* and moderate σ* bond electron filling and orbital occupation; thus, allowing moderate adsorption intensity for polysulfides and more effective d-p orbital hybridization to improve reaction kinetics. Meanwhile, this unique structure can dynamically balance the deposition and transport of Li on the anode; thereby, more effectively inhibiting Li dendrite growth and promoting the formation of a uniform solid electrolyte interface. The as-assembled Li-S full batteries exhibit the conspicuous capacities and ultralong cycling lifespan over 2000 cycles at 5.0 C. Even at a higher S loading (20 mg cm-2 ) and lean electrolyte (2.5 µL mg-1 ), the full cells can still achieve an ultrahigh areal capacity of 16.1 mAh cm-2 after 500 cycles at 0.1 C.

High-Efficiency Oxygen Evolution Reaction: Controllable Reconstruction of Surface Interface.

The precatalyst undergoes surface reconstruction during the oxygen evolution reaction (OER) process, and the reconstituted material is the one that really plays a catalytic role. However, the degree of surface reconstruction seriously affects the catalytic performance. For this reason, it is important to establish the link between the degree of reconstruction and catalytic activity based on a deep understanding of the OER mechanism for the rational design of high-performance OER electrocatalysts. Here, the reaction mechanism of OER is briefly introduced, the competition between adsorbate evolution mechanism (AEM) mechanism and lattice oxygen-mediated mechanism (LOM) mechanism is discussed, and several activity descriptors of OER reaction are summarized. The strategies to realize OER controllable surface reconstruction are emphatically introduced, including ion leaching, element doping, regulating catalyst size, heterogeneous structure engineering, and self-reconstruction. A mechanistic perspective is emphasized to understand the relationship between dynamic surface reconstruction and electronic structure. Controlled reconfiguration of OER surface can break the limitation of proportional relationship brought by traditional AEM mechanism, also can realize the switching between AEM mechanism and LOM mechanism, thus realizing ultra-low overpotential. This review will provide some reference for surface controllable reconstruction of OER transition metal-based catalysts and reasonable development of ideal catalytic performance.

Flower-Like NiS2 /WS2 Heterojunction as Polysulfide/sulfide Bidirectional Catalytic Layer for High-Performance Lithium-Sulfur Batteries.

The slow sulfur oxidation-reduction kinetics are one of the key factors hindering the widespread use of lithium-sulfur batteries (LSBs). Herein, flower-shaped NiS2 -WS2 heterojunction as the functional intercalation of LSBs is successfully prepared, and effectively improved the reaction kinetics of sulfur. Flower-like nanospheres composed of ultra-thin nanosheets (≤10 nm) enhance quickly transfer of mass and charge. Meanwhile, the heterostructures simultaneously serve as an electron receptor and a donor, thereby simultaneously accelerating the bidirectional catalytic activity of reduction and oxidation reactions in the LSBs. In addition, the adsorption experiment, chemical state analysis of elements before and after the reaction and theoretical calculation have effectively verified that NiS2 -WS2 heterojunction nanospheres optimize the adsorption capacity and bidirectional catalytic effect of polysulfides. The results show that the initial discharge capacity of NiS2 -WS2 functional intercalation is as high as 1518.7 mAh g-1 at 0.2 C. Even at a high current density of 5 C, it still shows a discharge specific capacity of 615.7 mAh g-1 , showing excellent rate performance. More importantly, the capacity is 258.9 mAh g-1 after 1500 cycles at 5 C, and the attenuation per cycle is only 0.039%, and the Coulomb efficiency remains above 95%.

Nitrogen Plasma Activates CoMn-Layered Double Hydroxides for Superior Electrochemical Oxygen Evolution.

Bimetallic layered double hydroxide is considered an ideal electrocatalytic material. However, due to the poor electrical conductivity of the bimetallic layered structure, obtaining highly active and stable catalysts through facile regulation strategies remains a great challenge. Herein, we use a simple corrosion strategy and nitrogen plasma technology to convert cobalt-based metal-organic frameworks into nitrogen-doped CoMn bimetallic layered double hydroxides (CoMn-LDH). Under the condition of regulating the local coordination environment of the catalytic active site and the presence of rich oxygen vacancy defects, N@CoMn-LDH/CC generates a low overpotential of 219 mV at 10 mA cm-2, which exceeds that of the commercial RuO2 catalyst. Density functional theory calculation shows that nitrogen doping improves the adsorption energy of the Mn site for oxygen evolution intermediates and reduces the reaction energy barrier of the Co site. Meanwhile, experiments and theoretical calculations verify that the mechanism of nitrogen doping regulating the oxygen evolution reaction (OER) follows the lattice oxygen oxidation mechanism, avoiding the collapse of the structure caused by catalyst reconstruction, thus improving the stability of oxygen evolution. This work provides a new simple strategy for the preparation of catalysts for a superior electrocatalytic oxygen evolution reaction.

A Tandem Interfaced (Ni3 S2 -MoS2 )@TiO2 Composite Fabricated by Atomic Layer Deposition as Efficient HER Electrocatalyst.

Reported herein is a highly active and durable hydrogen evolution reaction (HER) electrocatalyst, which is constructed following a tandem interface strategy and functional in alkaline and even neutral medium (pH ≈ 7). The ternary composite material, consisting of conductive nickel foam (NF) substrate, Ni3 S2 -MoS2 heterostructure, and TiO2 coating, is synthesized by the hydrothermal method and atomic layer deposition (ALD) technique. Representative results include: (1) versatile characterizations confirm the proposed composite structure and strong electronic interactions among comprised sulfide and oxide species; (2) the material outperforms commercial Pt/C by recording an overpotential of 115 mV and a Tafel slope of 67 mV dec-1 under neutral conditions. A long-term stability in alkaline electrolytes up to 200 h and impressive overall water splitting behavior (1.56 V @ 10 mA cm-2 ) are documented; (3) implementation of ALD oxide tandem layer is crucial to realize the design concept with superior HER performance by modulating a variety of heterointerface and intermediates electronic structure.

High Pseudocapacitance-Driven CoC2 O4 Electrodes Exhibiting Superior Electrochemical Kinetics and Reversible Capacities for Lithium-Ion and Lithium-Sulfur Batteries.

In this study, cuboid-like anhydrous CoC2 O4 particles (CoC2 O4 -HK) are synthesized through a potassium citrate-assisted hydrothermal method, which possess well-crystallized structure for fast Li+ transportation and efficient Li+ intercalation pseudocapacitive behaviors. When being used in lithium-ion batteries, the as-prepared CoC2 O4 -HK delivers a high reversible capacity (≈1360 mAh g-1 at 0.1 A g-1 ), good rate capability (≈650 mAh g-1 at 5 A g-1 ) and outstanding cycling stability (835 mAh g-1 after 1000 cycles at 1 A g-1 ). Characterizations illustrate that the Li+ -intercalation pseudocapacitance dominates the charge storage of CoC2 O4 -HK electrode, together with the reversible reaction of CoC2 O4 +2Li+ +2e- →Co+Li2 C2 O4 on discharging and charging. In addition, CoC2 O4 -HK particles are also used together with carbon-sulfur composite materials as the electrocatalysts for lithium-sulfur (Li-S) battery, which displays a gratifying sulfur electrochemistry with a high reversibility of 1021.5 mAh g-1 at 2 C and a low decay rate of 0.079% per cycle after 500 cycles. The density functional theory (DFT) calculations show that CoC2 O4 /C can regulate the adsorption-activation of reaction intermediates and therefore boost the catalytic conversion of polysulfides. Therefore, this work presents a new prospect of applying CoC2 O4 as the high-performance electrode materials for rechargeable Li-ion and Li-S batteries.

Hydroxylated Multi-Walled Carbon Nanotubes Covalently Modified with Tris(hydroxypropyl) Phosphine as a Functional Interlayer for Advanced Lithium-Sulfur Batteries.

We have successfully constructed a new type of intercalation membrane material by covalently grafting organic tris(hydroxypropyl)phosphine (THPP) molecules onto hydroxylated multi-walled carbon nanotubes (CNT-OH) as a functional interlayer for the advanced LSBs. The as-assembled interlayer has been demonstrated to be responsible for the fast conversion kinetics of polysulfides, the inhibition of polysulfide shuttle effect, as well as the formation of a stable solid electrolyte interphase(SEI) layer. By means of spectroscopic and electrochemical analysis, we further found THPP plays a key role in accelerating the conversion of polysulfides into low-ordered lithium sulfides and suppressing the loss of polysulfides, thus rendering the as-designed lithium-sulfur battery in this work a high capacity, excellent rate performance and long-term stability. Even at low temperatures, the capacity decay rate was only 0.036 % per cycle for 1700 cycles.

Strategic Atomic Layer Deposition and Electrospinning of Cobalt Sulfide/Nitride Composite as Efficient Bifunctional Electrocatalysts for Overall Water Splitting.

Reported herein is comprehensive study of a highly active and stable cobalt catalyst for overall water splitting. This composite SFCNF/Co1- x S@CoN, consisting of S-doped flexible carbon nanofiber (SFCNF) matrix, Co1- x S nanoparticles, and CoN coatings, is prepared by integration of electrospinning and atomic layer deposition (ALD) technique. Representative results include the following: 1) ultrathin CoN layer is deposited by ALD on the surface of flexible substrate without any sacrifice of SFCNF and Co1- x S; 2) the composite exhibits strong electrocatalytic activity in both acidic and basic solutions. The overpotentials of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are 20 and 180 mV, respectively, at a current density of 10 mA cm-2 in basic medium. A small Tafel slope of 54.4 mV dec-1 is observed in 0.5 m H2 SO4 electrolyte; 3) tested as overall water splitting electrode, the composite records a current density of 10 mA cm-2 at a relative low cell voltage of 1.58 V and long-term stability for 20 h at a current density of up to 50 mA cm-2 . The superior performance for overall water splitting is probably attributed to the synergistic effect of Co1- x S and ALD CoN. Specifically, implementation of ALD can be extended to innovate nanostructured materials for overall water splitting and even other renewable energy aspects.

Radially Inwardly Aligned Hierarchical Porous Carbon for Ultra-Long-Life Lithium-Sulfur Batteries.

Rational design of hollow micro- and/or nano-structured cathodes as sulfur hosts has potential for high-performance lithium-sulfur batteries. However, their further commercial application is hindered because infusing sulfur into hollow hosts is hard to control and the interactions between high loading sulfur and electrolyte are poor. Herein, we designed hierarchical porous hollow carbon nanospheres with radially inwardly aligned supporting ribs to mitigate these problems. Such a structure could aid the sulfur infusion and maximize sulfur utilization owing to the well-ordered pore channels. This highly organized internal carbon skeleton can also enhance the electronic conductivity. The hollow carbon nanospheres with further nitrogen-doping as the sulfur host material exhibit good capacity and excellent cycling performance (0.044 % capacity degradation per each cycle for 1000 cycles).

TT-10 may attenuate ibuprofen-induced ovarian injury in mice by activating COX2-PGE2 and inhibiting Hippo pathway.

Ibuprofen (IBU) is a non-steroidal anti-inflammatory drug that has been found in recent years to cause ovarian damage. The aim of this study is to explore the molecular mechanisms of IBU damage to the ovary and drugs to combat it. We established in vivo (IBU doses of 50, 100 and 200 mg/kg-day) and in vitro (IBU concentrations of 50, 100 and 200 µM in culture medium) models of ovarian damage in mice simulating clinical doses and found that IBU not only caused ovarian damage in mice in a dose-response relationship, but also decreased estradiol (E2) and prostaglandin E2 (PGE2) levels in serum/media with increasing IBU doses. In damaged ovaries, the cyclooxygenase 2 (COX2)-PGE2 pathway is inhibited, the Hippo pathway is activated, circPVT1 is decreased, and miR-149 is elevated. TT-10 is an activator of YES-associated protein (YAP)-transcriptional enhancer factor domain activity. Then, 100 µM IBU-induced ovarian damage model was selected for YAP activation (Hippo pathway inhibition) experiment, and TT-10 was found to interfere with IBU-induced ovarian damage and increase E2 level in the medium, and 10 µM of TT-10 had the best protective effect. TT-10 also inhibited the Hippo pathway, activated the COX2-PGE2 pathway, elevated circPVT1 expression, and decreased miR-149 expression in the ovary. It has been hypothesized that clinical doses of IBU damage mouse ovaries by inhibiting COX2-PGE2 and activating the Hippo pathway, whereas TT-10 protects the ovaries through the inverse regulation of these two pathways.

A restricted dynamic surface self-reconstruction toward high-performance of direct seawater oxidation.

The development of highly efficient electrocatalysts for direct seawater splitting with bifunctionality for inhibiting anodic oxidation reconstruction and selective oxygen evolution reactions is a major challenge. Herein, we report a direct seawater oxidation electrocatalyst that achieves long-term stability for more than 1000 h at 600 mA/cm2@η600 and high selectivity (Faraday efficiency of 100%). This catalyst revolves an amorphous molybdenum oxide layer constructed on the beaded-like cobalt oxide interface by atomic layer deposition technology. As demonstrated, a new restricted dynamic surface self-reconstruction mechanism is induced by the formation a stable reconstructed Co-Mo double hydroxide phase interface layer. The device assembled into a two-electrode flow cell for direct overall seawater electrolysis maintained at 1 A/cm2@1.93 V for 500 h with Faraday efficiency higher than 95%. Hydrogen generation rate reaches 419.4 mL/cm2/h, and the power consumption (4.62 KWh/m3 H2) is lower than that of pure water (5.0 KWh/m3 H2) at industrial current density.

Bivalent Cobalt as Efficient Catalyst Intercalation Layer Improves Polysulfide Conversion in Lithium-Sulfur Batteries.

Herein, we investigated in detail the effect of metal valences in different cobalt-based organic framework compounds on the kinetics of sulfur reaction in lithium-sulfur batteries (LSBs). On this basis, two organic framework compounds of zeolite-imidazole-based cobalt organic framework compound (Co-ZIF) and tetrakis(4-benzoic acid) porphyrinato-CoIII chloride [Co-TBP(III)] with different valences were constructed as the functional intercalation separators of LSBs, and explored the effects of different valences on improving the reaction kinetics of polysulfides and inhibiting the shuttle effect. Experiments and theoretical calculations prove that CoII exhibits the best catalytic activity. This is mainly due to the fact that +2 valence shows a strong adsorption energy for polysulfides and a higher Fermi level compared with +3 valence, thus improving the efficiency of the rapid catalytic conversion of sulfur species. As expected, the discharge specific capacity of Co-ZIF as the catalytic layer of the LSBs reached 772.7 mAh g-1 at a high current density of 5 C. More importantly, the initial specific capacity is 839.6 mAh g-1 at high current 3 C, and after 720 cycles, the attenuation rate of per cycle is only 0.092 %, and the coulombic efficiency remains above 92 %.

A Review on the Construction of Carbon-Based Metal Compound Composite Cathode Materials for Room Temperature Sodium-Sulfur Batteries.

Room temperature sodium-sulfur batteries are one of the most attractive energy storage systems due to their low cost, environmental friendliness, and ultra-high energy density. However, due to the inherent slow redox kinetics and the shuttle of polysulfides, the road of room temperature sodium-sulfur batteries to practical application is still full of difficulties. As a sulfur cathode, which is directly related to battery performance, a lot of research efforts have been devoted to it and many strategies have been proposed to solve the shuttle effect problem of sulfur cathodes. This paper analyzes the existing problems and solutions of sodium-sulfur batteries, mainly discusses and summarizes the research progress of constructing carbon-based cathode materials for sodium-sulfur batteries, and expounds the current research popular from two main directions. That is to construct advanced cathode materials based on two mechanisms of adsorption and electrocatalysis. Finally, the research direction of advanced sodium-sulfur batteries is prospected.

Tuning the Interface of Co1-xS/Co(OH)F by Atomic Replacement Strategy toward High-Performance Electrocatalytic Oxygen Evolution.

The construction of heterostructures is one of the most promising strategies for engineering interfaces of catalysts to perform high-efficiency oxygen evolution reaction (OER). However, accurately tuning heterostructures' interface during operation remains a challenge. Herein, we fabricated the needled-like heterostructure Co1-xS/Co(OH)F supported on flexible carbon fiber cloth via an atomic substitution strategy, in which sulfur atoms are simultaneously grafted into F vacancies after the partial removal of F atoms from Co(OH)F during the electrodeposition, thus achieving the growth of cobalt sulfide on the interface of Co(OH)F. This electrocatalyst with such design exhibits the following advantages: (1) The lattice distortion caused by atomic substitution leads to the increase of active sites; (2) Co1-xS constructed on the surface of Co(OH)F by the atomic replacement strategy optimizes the adsorption (OH-) and desorption (O2) energy in the OER process; (3) the needle-like structure possesses the tip-enhanced local electric field effect. As a result, the Co1-xS/Co(OH)F/CC catalyst exhibits very high OER catalytic performance with an overpotential of 269 mV at a current density of 10 mA cm-2 and a Tafel slope of 71 mV dec-1. The asymmetric electrode shows superior catalytic activity and stability in overall water splitting. The catalytic mechanism of these highly efficient Co1-xS/Co(OH)F/CC catalysts was investigated via DFT theoretical calculations and ex situ characterizations. This atomic substitution strategy displays universality for other transition metal sulfides (metal = Ni, Mn, Cu).

Toward High-Performance Lithium-Sulfur Batteries: Efficient Anchoring and Catalytic Conversion of Polysulfides Using P-Doped Carbon Foam.

Rational design of the sulfur cathode structure enables effective adsorption of polysulfides and accelerates the sulfur reduction reaction, which is of great significance to the practical application of lithium-sulfur batteries. Here, P-doped carbon foam (PCF) as a sulfur host for the lithium-sulfur battery cathode was successfully synthesized by a facile strategy. The tailored hierarchical pore structure combined with P doping not only facilitates Li+ diffusion but also enhances the adsorption and accelerates the catalytic conversion of lithium polysulfides, thus significantly improving lithium storage performance of the PCF/S cathode.

Molybdenum Carbide Nanoparticles Coated into the Graphene Wrapping N-Doped Porous Carbon Microspheres for Highly Efficient Electrocatalytic Hydrogen Evolution Both in Acidic and Alkaline Media.

Molybdenum carbide (Mo2C) is recognized as an alternative electrocatalyst to noble metal for the hydrogen evolution reaction (HER). Herein, a facile, low cost, and scalable method is provided for the fabrication of Mo2C-based eletrocatalyst (Mo2C/G-NCS) by a spray-drying, and followed by annealing. As-prepared Mo2C/G-NCS electrocatalyst displays that ultrafine Mo2C nanopartilces are uniformly embedded into graphene wrapping N-doped porous carbon microspheres derived from chitosan. Such designed structure offer several favorable features for hydrogen evolution application: 1) the ultrasmall size of Mo2C affords a large exposed active sites; 2) graphene-wrapping ensures great electrical conductivity; 3) porous structure increases the electrolyte-electrode contact points and lowers the charge transfer resistance; 4) N-dopant interacts with H+ better than C atoms and favorably modifies the electronic structures of adjacent Mo and C atoms. As a result, the Mo2C/G-NCS demonstrates superior HER activity with a very low overpotential of 70 or 66 mV to achieve current density of 10 mA cm-2, small Tafel slope of 39 or 37 mV dec-1, respectively, in acidic and alkaline media, and high stability, indicating that it is a great potential candidate as HER electrocatalyst.