Water-Trapping Single-Atom Co-N4/Graphene Triggering Direct 4e− LiOH Chemistry for Rechargeable Aprotic Li–O2 Batteries

Lithium–oxygen (Li–O₂) batteries have received extensive attention owing to ultrahigh theoretical energy density. Compared to typical discharge product Li₂O₂, LiOH has attracted much attention for its better chemical and electrochemical stability. Large-scale applications of Li–O₂ batteries with LiOH chemistry are hampered by the serious internal shuttling of the water additives with the desired 4e⁻ electrochemical reactions. Here, a metal organic framework-derived “water-trapping” single-atom-Co-N₄/graphene catalyst (Co-SA-rGO) is provided that successfully mitigates the water shuttling and enables the direct 4e⁻ catalytic reaction of LiOH in the aprotic Li–O₂ battery. The Co-N₄ center is more active toward proton-coupled electron transfer, benefiting - direction 4e⁻ formation of LiOH. 3D interlinked networks also provide large surface area and mesoporous structures to trap ≈12 wt% H₂O molecules and offer rapid tunnels for O₂ diffusion and Li⁺ transportation. With these unique features, the Co-SA-rGO based Li–O₂ battery delivers a high discharge platform of 2.83 V and a large discharge capacity of 12 760.8 mAh g⁻¹. Also, the battery can withstand corrosion in the air and maintain a stable discharge platform for 220 cycles. This work points out the direction of enhanced electron/proton transfer for the single-atom catalyst design in Li–O₂ batteries.     

Amorphous Vanadium Oxide Nanosheets with Alterable Polyhedron Configuration for Fast-Charging Lithium-Ion Batteries

Transition metal oxides with high theoretical capacities are promising anode materials for lithium-ion batteries (LIBs). However, the sluggish reaction kinetics remain a bottleneck for fast-charging applications due to its slow Li⁺ migration rate. Herein, a strategy is reported of significantly reducing the Li⁺ diffusion barrier of amorphous vanadium oxide by constructing a specific ratio of the V O local polyhedron configuration in amorphous nanosheets. The optimized amorphous vanadium oxide nanosheets with a ratio ≈1:4 for octahedron sites (O_h) to pyramidal sites (C_4v) revealed by Raman spectroscopy and X-ray absorption spectroscopy (XAS) demonstrate the highest rate capability (356.7 mA h g⁻¹ at 10.0 A g⁻¹) and long-term cycling life (455.6 mA h g⁻¹ at 2.0 A g⁻¹ over 1200 cycles). Density functional theory (DFT)calculations further verify that the local structure (O_h:C_4v = 1:4) intrinsically changes the degree of orbital hybridization between V and O atoms and contributes to a higher intensity of electron occupied states near the Fermi level, thus resulting in a low Li⁺ diffusion barrier for favorable Li⁺ transport kinetics. Moreover, the amorphous vanadium oxide nanosheets possess a reversible V O vibration mode and volume expansion rate close to 0.3%, as determined through in situ Raman and in situ transmission electron microscopy.     

Highly Selective Photoreduction of CO2 with Suppressing H2 Evolution by Plasmonic Au/CdSe–Cu2O Hierarchical Nanostructures under Visible Light

Here, the photocatalytic CO₂ reduction reaction (CO₂RR) with the selectivity of carbon products up to 100% is realized by completely suppressing the H₂ evolution reaction under visible light (λ > 420 nm) irradiation. To target this, plasmonic Au/CdSe dumbbell nanorods enhance light harvesting and produce a plasmon‐enhanced charge‐rich environment; peripheral Cu₂O provides rich active sites for CO₂ reduction and suppresses the hydrogen generation to improve the selectivity of carbon products. The middle CdSe serves as a bridge to transfer the photocharges. Based on synthesizing these Au/CdSe–Cu₂O hierarchical nanostructures (HNSs), efficient photoinduced electron/hole (e^?/h⁺) separation and 100% of CO selectivity can be realized. Also, the 2e^?/2H⁺ products of CO can be further enhanced and hydrogenated to effectively complete 8e^?/8H⁺ reduction of CO₂ to methane (CH₄), where a sufficient CO concentration and the proton provided by H₂O reduction are indispensable. Under the optimum condition, the Au/CdSe–Cu₂O HNSs display high photocatalytic activity and stability, where the stable gas generation rates are 254 and 123 µmol g^?1 h^?1 for CO and CH₄ over a 60 h period.     

Calculations of the Elastic Scattering Properties of Ultra-cold Francium Isotopes

The calculations of the elastic scattering properties of ultra-cold francium isotopes are reported in detail. A parametric model potential for the triplet molecular states of the Fr₂ is represented, and the scattering lengths a_t and the effective range r_e are calculated using WKB and Numerov methods for Fr--Fr in the triplet state. The convergence of these scattering properties depending on a K⁰ parameter and core radius is also investigated using two methods: Quantum Defect Theory and analytical formula of Symskoviski.     

Long-Cycling-Life Sodium-Ion Battery Using Binary Metal Sulfide Hybrid Nanocages as Anode

Due to the relatively high capacity and lower cost, transition metal sulfides (TMS) as anode show promising potential in sodium-ion batteries (SIBs). Herein, a binary metal sulfide hybrid consisting of carbon encapsulated CoS/Cu₂S nanocages (CoS/Cu₂S@C-NC) is constructed. The interlocked hetero-architecture filled with conductive carbon accelerates the Na⁺/e⁻ transfer, thus leading to improved electrochemical kinetics. Also the protective carbon layer can provide better volume accommondation upon charging/discharging. As a result, the battery with CoS/Cu₂S@C-NC as anode displays a high capacity of 435.3 mAh g⁻¹ after 1000 cycles at 2.0 A g⁻¹ (≈3.4 C). Under a higher rate of 10.0 A g⁻¹ (≈17 C), a capacity of as high as 347.2 mAh g⁻¹ is still remained after long 2300 cycles. The capacity decay per cycle is only 0.017%. The battery also exhibits a better temperature tolerance at 50 and −5 °C. A low internal impedance analyzed by X-ray diffraction patterns and galvanostatic intermittent titration technique, narrow band gap, and high density of states obtained by first-principle calculations of the binary sulfides, ensure the rapid Na⁺/e⁻ transport. The long-cycling-life SIB using binary metal sulfide hybrid nanocages as anode shows promising applications in versatile electronic devices.     

Electron Injection via Interfacial Atomic Au Clusters Substantially Enhance the Visible-Light-Driven Photocatalytic H2 Production of the PF3T Enclosed TiO2 Nanocomposite

A hybrid composite of organic–inorganic semiconductor nanomaterials with atomic Au clusters at the interface decoration (denoted as PF3T@Au-TiO₂) is developed for visible–light-driven H₂ production via direct water splitting. With a strong electron coupling between the terthiophene groups, Au atoms and the oxygen atoms at the heterogeneous interface, significant electron injection from the PF3T to TiO₂ occurs leading to a quantum leap in the H₂ production yield (18 578 µmol g⁻¹ h⁻¹) by ≈39% as compared to that of the composite without Au decoration (PF3T@TiO₂, 11 321 µmol g⁻¹ h⁻¹). Compared to the pure PF3T, such a result is 43-fold improved and is the best performance among all the existing hybrid materials in similar configurations. With robust process control via industrially applicable methods, it is anticipated that the findings and proposed methodologies can accelerate the development of high-performance eco-friendly photocatalytic hydrogen production technologies.     

Triplet molecules of the D5 symmetry group based on C60 fullerene

The possibility of observing a non-zero-spin triplet state in highly symmetric derivatives of fullerene molecules with five double bonds, representing isomers of the type D₅-C₆₀(R-r ₆-R)₅ (where R = H or CH₃), is assessed based on the results of quantum-chemical calculations. The energies of isomer formation (endo-and exothermal process for the hydrogenated and methylated isomers, respectively) and the energies of terms are determined. The ground state corresponding to a non-zero-spin triplet e ₁ ² (³A₂) occurs approximately 0.3 eV below the zero-spin states. The results can be interpreted within the framework of the tight binding approximation for the pπ basis set orbitals of fullerene molecules (representing radially directed C2p hybrid atomic orbitals). The character of the open electron shell of isomers, delocalized over a large fullerene surface, suggests that, with high probability, the above non-zero-spin triplet state (rather than the e ₁ ² (¹E₂) state stabilized by the Jahn-Teller effect) is the ground state of the system.     

NiS/Cd0.6Zn0.4S Schottky Junction Bifunctional Photocatalyst for Sunlight-Driven Highly Selective Catalytic Oxidation of Vanillyl Alcohol Towards Vanillin Coupled with Hydrogen Evolution Reaction

Selective oxidation of biomass-based molecules to high-value chemicals in conjunction with hydrogen evolution reaction (HER) is an innovative photocatalysis strategy. The key challenge is to design bifunctional photocatalysts with suitable band structures, which can achieve highly efficient generation of high-value chemicals and hydrogen. Herein, NiS/Cd_0.6Zn_0.4S Schottky junction bifunctional catalysts are constructed for sunlight-driven catalytic vanillyl alcohol (VAL) selective oxidation towards vanillin (VN) coupling HER. At optimal conditions, the 8% NiS/Cd_0.6Zn_0.4S photocatalyst achieves high activity of VN production (3.75 mmol g⁻¹ h⁻¹) and HER (3.84 mmol g⁻¹ h⁻¹). It also exhibits remarkable VAL conversion (66.9%), VN yield (52.1%), and selectivity (77.8%). The photocatalytic oxidation of VAL proceeds a carbon-centered radical mechanism via the cleavage of α_C–H bond. Experimental results and theoretical calculations show that NiS with metallic properties enhances the electron transfer capability. Importantly, a Ni-S-Cd “electron bridge” formed at the interface of NiS/Cd_0.6Zn_0.4S further improves the separation/transfer of electrone/h⁺ pairs and also furnishes HER active sites due to its smaller the |ΔG_H*| value, thereby resulting in a remarkably HER activity. This work sheds new light on the selective catalytic oxidation VAL to VN coupling HER, with a new pathway towards achieving its efficient HER efficiency.     

Mesoporous Ti-MCM-41 materials as photodegradation catalysts of 2,4,6-trichlorophenol in water

Titanium-modified MCM-41 type mesoporous silica materials were prepared by hydrothermal [Ti-MCM-41(HT)], sol–gel [Ti-MCM-41(SG)] and post-synthesis impregnation [TiO₂/MCM-41] methods. The materials were characterized and tested as photocatalysts in the oxidative degradation reaction of 2,4,6-trichlorophenol (2,4,6-TCP) in water. The catalysts showed high initial activity. The produced acetate and chloride ions were found to inhibit the degradation reaction. The Ti-MCM-41(HT) sample showed higher overall activity than the Ti-MCM-41(SG) catalyst. One of the probable reasons for this is the difference in the distribution of the active sites that determines the rates of electron (e⁻)–hole (h⁺) recombination within the photoactive species. The HT preparation was found to contain silica-bound titania in higher dispersion, while the SG preparation contained also polymerized species with Ti–O–Ti bonds.     

Improved Photo-Excited Carriers Transportation of WS2-O-Doped-Graphene Heterostructures for Solar Steam Generation (Small 19/2023)

Two-dimensional (2D) transition metal dichalcogenides and graphene have revealed promising applications in optoelectronic and energy storage and conversion. However, there are rare reports of modifying the light-to-heat transformation via preparing their heterostructures for solar steam generation. In this work, commercial WS₂ and sucrose are utilized as precursors to produce 2D WS₂-O-doped-graphene heterostructures (WS₂-O-graphene) for solar water evaporation. The WS₂-O-graphene evaporators demonstrate excellent average water evaporation rate (2.11 kg m⁻² h⁻¹) and energy efficiency (82.2%), which are 1.3- and 1.2-fold higher than WS₂ and O-doped graphene-based evaporators, respectively. Furthermore, for the real seawater with different pH values (pH 1 and 12) and rhodamine B pollutants, the WS₂-O-graphene evaporators show great average evaporation rates (≈2.08 and 2.09 kg m⁻² h⁻¹, respectively) for producing freshwater with an extremely low-grade of dye residual and nearly neutral pH values. More interestingly, due to the self-storage water ability of WS₂-O-graphene evaporators, water evaporation can be implemented without the presence of bulk water. As a result, the evaporation rate reaches 3.23 kg m⁻² h⁻¹, which is ≈1.5 times higher than the regular solar water evaporation system. This work provides a new approach for preparing 2D transition metal dichalcogenides and graphene heterostructures for efficient solar water evaporation.     

Photoelectronic properties of HgI2 crystals for nuclear radiation detection

Photoelectronic properties of red mercuric iodide single crystals, grown from its saturated solution in tetrahydrofuran, have been studied for the wavelength range 450–700 nm at temperatures 80,110, 175, 235 and 300 K. Various aspects of the optical generation of charge carriers have been discussed. The computer simulation of the room temperature photoconductivity has generated the optimized values of the mobility-lifetime products μ_eτ_e = 5.67 × 10⁻⁵ cm²/V, μ_hτ_h = 0.18 × 10⁻⁵ cm²/V), and surface recombination velocities (S_e = 3.2 × 10⁵ cm/s, S_h = 4.5 × 10⁵ cm/s) of the charge carriers in these crystals. The estimated values of the electron and hole drift lengths for typical electric fields suggest that, under the negative electrode illumination, THF α-HgI₂ crystals have high potential as regards to their use as photodetectors in most of the scintillation spectrometers.     

TiO2@Perylene Diimide Full‐Spectrum Photocatalysts via Semi‐Core–Shell Structure

A semi‐core–shell structure of perylene diimide (PDI) self‐assembly coated with TiO₂ nanoparticles is constructed, in which nanoscale porous TiO₂ shell is formed and PDI self‐assembly presented 1D structure. A full‐spectrum photocatalyst is obtained using this structure to resolve a conundrum—TiO₂ does not exhibit visible‐light photocatalytic activity while PDI does not exhibit ultraviolet photocatalytic activity. Furthermore, the synergistic interaction between TiO₂ and PDI enables the catalyst to improve its ultraviolet, visible‐light, and full‐spectrum performance. The interaction between TiO₂ and PDI leads to formation of some new stacking states along the Π–Π stacking direction and, as a consequence, electron transfer from PDI to TiO₂ suppresses the recombination of e^?/h⁺ and thus improves photocatalytic performance. But the stronger interaction in the interface between TiO₂ and PDI is not in favor of photocatalytic performance, which leads to rapid charge recombination due to more disordered stacking states. The study provides a theoretical direction for the study of core–shell structures with soft materials as a core, and an idea for efficient utilization of solar energy.     

Highly Efficient Photocatalytic Hydrogen Evolution by ReS2 via a Two‐Electron Catalytic Reaction

Highly efficient photocatalytic hydrogen evolution (PHE) is highly desirable for addressing the global energy crisis and environmental problems. Although much attention has been given to electron–hole separation, ridding photocatalysts of poor efficiency remains challenging. Here, a two‐electron catalytic reaction is developed by utilizing the distinct trion behavior of ReS₂ and the efficient reduction of two H⁺ (2H⁺ + 2e^? → H₂) is realized. Due to the monolayer‐like structure of the catalyst, the free electrons in ReS₂ can be captured by the tightly bound excitons to form trions consisting of two electrons and one hole. These trions can migrate to the surface and participate in the two‐electron reaction at the abundant active sites. As expected, such a two‐electron catalytic reaction endows ReS₂ with a PHE rate of 13 mmol g^?1 h^?1 under visible light irradiation. Meanwhile, this reaction allows the typically poor PHE efficiency of pure transition metal dichalcogenides to be overcome. The proposed two‐electron catalytic reaction provides a new approach to the design of photocatalysts for PHE.     

Z-Scheme Modulated Charge Transfer on InVO4@ZnIn2S4 for Durable Overall Water Splitting

The charge transfer within heterojunction is crucial for the efficiency and stability of photocatalyst for overall water splitting (OWS). Herein, InVO₄ nanosheets have been employed as a support for the lateral epitaxial growth of ZnIn₂S₄ nanosheets to produce hierarchical InVO₄@ZnIn₂S₄ (InVZ) heterojunctions. The distinct branching heterostructure facilitates active site exposure and mass transfer, further boosting the participation of ZnIn₂S₄ and InVO₄ for proton reduction and water oxidation, respectively. The unique Z-scheme modulated charge transfer, visualized by simulation and in situ analysis, has been proved to promote the spatial separation of photoexcited charges and strengthen the anti-photocorrosion capability of InVZ. The optimized InVZ heterojunction presents improved OWS (153.3 µmol h⁻¹ g⁻¹ for H₂ and 76.9 µmol h⁻¹ g⁻¹ for O₂) and competitive H₂ production (21090 µmol h⁻¹ g⁻¹). Even after 20 times (100 h) of cycle experiment, it still holds more than 88% OWS activity and a complete structure.     

Pyrazine-Functionalized Donor–Acceptor Covalent Organic Frameworks for Enhanced Photocatalytic H2 Evolution with High Proton Transport

The well-defined 2D or 3D structure of covalent organic frameworks (COFs) makes it have great potential in photoelectric conversion and ions conduction fields. Herein, a new donor–accepter (D–A) COF material, named PyPz-COF, constructed from electron donor 4,4′,4″,4′″-(pyrene-1,3,6,8-tetrayl)tetraaniline and electron accepter 4,4′-(pyrazine-2,5-diyl)dibenzaldehyde with an ordered and stable π-conjugated structure is reported. Interestingly, the introduction of pyrazine ring endows the PyPz-COF a distinct optical, electrochemical, charge-transfer properties, and also brings plentiful CN groups that enrich the proton by hydrogen bonds to enhance the photocatalysis performance. Thus, PyPz-COF exhibits a significantly improved photocatalytic hydrogen generation performance up to 7542 µmol g⁻¹ h⁻¹ with Pt as cocatalyst, also in clear contrast to that of PyTp-COF without pyrazine introduction (1714 µmol g⁻¹ h⁻¹). Moreover, the abundant nitrogen sites of the pyrazine ring and the well-defined 1D nanochannels enable the as-prepared COFs to immobilize H₃PO₄ proton carriers in COFs through hydrogen bond confinement. The resulting material has an impressive proton conduction up to 8.10 × 10⁻² S cm⁻¹ at 353 K, 98% RH. This work will inspire the design and synthesis of COF-based materials with both efficient photocatalysis and proton conduction performance in the future.     

Ultrasound-Activatable g-C3N4-Anchored Titania Heterojunction as an Intracellular Redox Homeostasis Perturbator for Augmented Oncotherapy

Energy band structure of inorganic nano-sonosensitizers is usually optimized by surface decoration with noble metals or metal oxide semiconductors, aiming to enhance interfacial charge transfer, augment spin-flip and promote radical generation. To avoid potential biohazards of metallic elements, herein, metal-free graphitic carbon nitride quantum dots (g-C₃N₄ QDs) are anchored onto hollow mesoporous TiO₂ nanostructure to formulate TiO₂@g-C₃N₄ heterojunction. The direct Z-scheme charge transfer significantly improves the separation/recombination dynamics of electron/hole (e⁻/h⁺) pairs upon ultrasound (US) stimulation, which promotes the yield of singlet oxygen (¹O₂) and hydroxyl radicals (·OH). The conjugated g-C₃N₄ QDs with peroxidase-mimic activity further react with the elevated endogenous H₂O₂ and aggravate oxidative stress. After loading prodrug romidepsin (RMD) in TiO₂@g-C₃N₄, stimulus-responsive drug delivery can be realized by US irradiation. The disulfide bridge of the released RMD tends to be reduced by glutathione (GSH) into a monocyclic dithiol, which arrests cell cycle in G2/M phase and evokes apoptosis through enhanced histone acetylation. Importantly, reactive oxygen species accumulation accompanied by GSH depletion is devoted to deleterious redox dyshomeostasis, leading to augmented systemic oncotherapy by eliciting antitumor immunity. Collectively, this paradigm provides useful insights in optimizing the performance of TiO₂-based nano-sonosensitizers for tackling critical diseases.     

Enhanced the Efficiency of Electrocatalytic CO2-to-CO Conversion by Cd Species Anchored into Metal-Organic Framework

Metal-organic frameworks (MOFs) as a promising platform for electrocatalytic CO₂ conversion are still restricted by the low efficiency or unsatisfied selectivity for desired products. Herein, zirconium-based porphyrinic MOF hollow nanotubes with Cd sites (Cd-PCN-222HTs) are reported for electrocatalytic CO₂-to-CO conversion. The dispersed Cd species are anchored in PCN-222HTs and coordinated by N atoms of porphyrin structures. It is discovered that Cd-PCN-222HTs have glorious electrocatalytic activity for selective CO production in ionic liquid-water (H₂O)-acetonitrile (MeCN) electrolyte. The CO Faradaic efficiency (FE_CO) of >80% could be maintained in a wide potential range from −2.0 to −2.4 V versus Ag/Ag⁺, and the maximum current density could reach 68.0 mA cm⁻² at −2.4 V versus Ag/Ag⁺ with a satisfied turnover frequency of 26 220 h⁻¹. The enhanced efficiency of electrocatalytic CO₂ conversion of Cd-PCN-222HTs is closely related to its hollow structure, anchored Cd species, and good synergistic effect with electrolyte. The density functional theory calculations indicate that the dispersed Cd sites anchored in PCN-222HTs not only favor the formation of *COOH intermediate but also hinder the hydrogen evolution reaction, resulting in high activity of electrocatalytic CO₂-to-CO conversion.     

Highly efficient nanostructured metal-decorated hybrid semiconductors for solar conversion of CO2 with almost complete CO selectivity

Photocatalytic reduction of CO₂ into solar fuels is regarded as a promising method to address global warming and energy crisis problems. Although heterostructured hybrid metal oxide catalysts have been used for CO₂ reduction, selective control for CO production-only remains the subject of debate. In this paper, we report an absolute selectivity for CO production-only with enhanced photocatalytic ability using Ag-decorated reduced titanium oxide/tungsten hybrid nanoparticles (blue TiO₂/WO₃–Ag HNPs) at 1166.72 μmol g⁻¹ h⁻¹ with an apparent quantum yield of 34.8%. The construction of a Z-scheme between blue TiO₂ and WO₃ domains with an excellent band alignment provided remarkably improved separation of photoinduced charges. Importantly, the presence of novel Ag not only produces the highest selectivity up to 100% CO production-only, but also increases the photocatalytic electron reaction rate (2333.44 μmol g⁻¹ h⁻¹).     

Sulfur Loading and Speciation Control the Hydrophobicity,Electron Transfer,Reactivity, and Selectivity of Sulfidized Nanoscale Zerovalent Iron

Sulfidized nanoscale zerovalent iron (SNZVI) is a promising material for groundwater remediation. However, the relationships between sulfur content and speciation and the properties of SNZVI materials are unknown, preventing rational design. Here, the effects of sulfur on the crystalline structure, hydrophobicity, sulfur speciation, corrosion potential, and electron transfer resistance are determined. Sulfur incorporation extended the nano-Fe⁰ BCC lattice parameter, reduced the Fe local vacancies, and lowered the resistance to electron transfer. Impacts of the main sulfur species (FeS and FeS₂) on hydrophobicity (water contact angles) are consistent with density functional theory calculations for these FeS_x phases. These properties well explain the reactivity and selectivity of SNZVI during the reductive dechlorination of trichloroethylene (TCE), a hydrophobic groundwater contaminant. Controlling the amount and speciation of sulfur in the SNZVI made it highly reactive (up to 0.41 L m⁻² d⁻¹) and selective for TCE degradation over water (up to 240 moles TCE per mole H₂O), with an electron efficiency of up to 70%, and these values are 54-fold, 98-fold, and 160-fold higher than for NZVI, respectively. These findings can guide the rational design of robust SNZVI with properties tailored for specific application scenarios.     

In Situ Fabrication of Hierarchically Branched TiO2 Nanostructures: Enhanced Performance in Photocatalytic H2 Evolution and Li–Ion Batteries

1D branched TiO₂ nanomaterials play a significant role in efficient photocatalysis and high‐performance lithium ion batteries. In contrast to the typical methods which generally have to employ epitaxial growth, the direct in situ growth of hierarchically branched TiO₂ nanofibers by a combination of the electrospinning technique and the alkali‐hydrothermal process is presented in this work. Such the branched nanofibers exhibit improvement in terms of photocatalytic hydrogen evolution (0.41 mmol g⁻¹ h⁻¹), in comparison to the conventional TiO₂ nanofibers (0.11 mmol g⁻¹ h⁻¹) and P25 (0.082 mmol g⁻¹ h⁻¹). Furthermore, these nanofibers also deliver higher lithium specific capacity at different current densities, and the specific capacity at the rate of 2 C is as high as 201. 0 mAh g⁻¹, roughly two times higher than that of the pristine TiO₂ nanofibers.