Heteroatom- and Bonded Z-Scheme Channels-Modulated Ultrafast Carrier Dynamics and Exciton Dissociation in Covalent Triazine Frameworks for Efficient Photocatalytic Hydrogen Evolution

Covalent triazine frameworks (CTF) offer a tunable platform for photocatalytic H₂ generation due to their diverse structures, low costs, and precisely tunable electronic structures. However, high exciton binding energy and short lifetimes of photogenerated carriers restrict their application in photocatalytic hydrogen evolution. Herein, a novel phosphorus-incorporated CTF is introduced to construct a chemically bonded PCTF/WO₃ (PCTFW) heterostructure with a precise interface electron transfer channel. The phosphorus incorporation is found to dominantly reduce the exciton binding energy and promote the dissociation of singlet and triplet excitons into free charge carriers due to the regulation of electronic structures. High-quality interfacial W N bonds improve the interfacial transfer of photogenerated electrons, thus prolonging the lifetime of photogenerated electrons. Femtosecond transient absorption spectroscopy characterizations and DFT calculations further confirm both phosphorus incorporation and Z-scheme heterojunctions can synergistically boost the in-built electric field and accelerate the migration and separation of photogenerated electrons. The optimized photocatalytic H₂-evolution rate of resultant PCTFW is 134.84 µmol h⁻¹ (67.42 mmol h⁻¹g⁻¹), with an apparent quantum efficiency of 37.63% at 420 nm, surpassing many reported CTF-based photocatalysts so far. This work highlights the significance of atom-level interfacial exciton dissociation, and charge transfer and separation in improving photocatalysis.     

Atomistic Structural Engineering of Conjugated Microporous Polymers Promotes Photocatalytic Biomass Valorization

Polymer photocatalysts have great promise for solar fuel production due to their flexible structural and functional designability. However, their photocatalytic efficiencies are still unsatisfactory, limited by their intrinsically large exciton binding energy and fast charge recombination. Herein, the atomistic structural engineering of donor–acceptor (D−A) polymer photocatalysts for enhanced charge separation and photocatalytic hydrogen production is proposed. By changing the electron affinity of the acceptor units, the electron delocalization and exciton binding energy of the polymeric networks can be readily tuned, resulting in enhanced charge separation efficiency and photocatalytic activity. The optimal sample shows the highest H₂ production rate of 3207 µmol g⁻¹ h⁻¹ in the presence of ascorbic acid as the sacrificial agent. Moreover, the photocatalytic H₂ production can be coupled with almost stoichiometrical conversion of 5-hydroxymethyl furfural to 2,5-diformylfuran.     

Simultaneously Tuning Band Structure and Oxygen Reduction Pathway toward High-Efficient Photocatalytic Hydrogen Peroxide Production Using Cyano-Rich Graphitic Carbon Nitride

The demands for green production of hydrogen peroxide have triggered extensive studies in the photocatalytic synthesis, but most photocatalysts suffer from rapid charge recombination and poor 2e⁻ oxygen reduction reaction (ORR) selectivity. Here, a novel composite photocatalyst of cyano-rich graphitic carbon nitride g-C₃N₄ is fabricated in a facile manner by sodium chloride-assisted calcination on dicyandiamide. The obtained photocatalysts exhibit superior activity (7.01 mm  h⁻¹ under λ  ≥  420 nm, 16.05 mm  h⁻¹ under simulated sun conditions) for H₂O₂ production and 93% selectivity for 2e⁻ ORR, much higher than that of the state-of-the-art photocatalyst. The porous g-C₃N₄ with Na dopants and cyano groups simultaneously optimize two limiting steps of the photocatalytic 2e⁻ ORR: photoactivity, and selectivity. The cyano groups can adjust the band structure of g-C₃N₄ to achieve high activity. They also serve as oxygen adsorption sites, in which local charge polarization facilitates O₂ adsorption and protonation. With the aid of Na⁺, the O₂ is reduced to produce more superoxide radicals as the intermediate products for H₂O₂ synthesis. This work provides a facile approach to simultaneously tune photocatalytic activity and 2e⁻ ORR selectivity for boosting H₂O₂ production, and then paves the way for the practical application of g-C₃N₄ in environmental remediation and energy supply.     

Visible light photocatalytic performance of hierarchical BiOBr microspheres synthesized via a reactable ionic liquid

Hierarchical BiOBr microspheres were synthesized via a one-pot solvothermal process in the presence of ethylene glycol and 1-butyl-3-methylimidazolium bromide ([BMIM]Br) as a reactable ionic liquid. The products were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance absorption spectra, nitrogen adsorption–desorption measurements, and photoluminescence spectroscopy. The photocatalytic activity of BiOBr microspheres was evaluated in terms of the degradation of Rhodamine B (RhB), methyl orange (MO), and 4-chlorophenol (4-CP) under visible light irradiation. We found that the solvothermal temperature had important effects on the crystallinity, crystallite size, optical property, adsorptive performance, and photocatalytic activity of BiOBr microspheres. BiOBr microspheres with a specific surface area of 15.7 m² g⁻¹ prepared at 160 °C exhibited the best adsorption and photocatalytic performance for RhB degradation in aqueous solution. However, this sample showed hardly any activity for photodegradation of 4-CP. Tests using radical scavengers confirmed that h⁺ and O₂⁻ were the main reactive species during RhB degradation. A possible mechanism for photocatalysis by BiOBr microspheres is proposed.     

Surface Energy Mediated Sulfur Vacancy of ZnIn2S4 Atomic Layers for Photocatalytic H2O2 Production

Constructing rich defect active site structure for material design is still a great challenge. Herein, a simple surface engineering strategy is demonstrated to construct one-unit-cell ZnIn₂S₄ atomic layers with the modulated surface energy of S vacancy. Rich surface energy can regulate and control the rich S vacancy, which ensures rich active sites, higher charge density and effective carrier transport. As a result, the ZnIn₂S₄ atomic layers with rich surface energy affords an obvious enhancement in H₂O₂ productive rate of 1592.04 µmol g⁻¹ h⁻¹, roughly 14.58 times superior to that with poor surface energy. Moreover, the in situ infrared diffuse reflection spectrum indicates that S vacancy as the oxygen reduction reaction active site is responsible for the critical intermediate *O₂⁻ and *OOH, corresponding to two-electron oxygen reduction reaction. This study provides a valuable insight and guidance for constructing controllably defects to achieve highly efficient H₂O₂ production.     

In Situ Topochemical Transformation of ZnIn2S4 for Efficient Photocatalytic Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran

Photocatalytic selective oxidation of 5-hydroxymethylfurfural (HMF) coupled H₂ production offers a promising approach to producing valuable chemicals. Herein, an efficient in situ topological transformation tactic is developed for producing porous O-doped ZnIn₂S₄ nanosheets for HMF oxidation cooperative with H₂ evolution. Aberration-corrected high-angle annular dark-field scanning TEM images show that the hierarchical porous O-ZIS-120 possesses abundant atomic scale edge steps and lattice defects, which is beneficial for electron accumulation and molecule adsorption. The optimal catalyst (O-ZIS-120) exhibits remarkable performance with 2,5-diformylfuran (DFF) yields of 1624 µmol h⁻¹ g⁻¹ and the selectivity of >97%, simultaneously with the H₂ evolution rate of 1522 µmol h⁻¹ g⁻¹. Mechanistic investigations through theoretical calculations show that O in the O-ZIS-120 lattice can reduce the oxidation energy barrier of hydroxyl groups of HMF. In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) results reveal that DFF^* (C₄H₂(CHO)₂O^*) intermediate has a weak interaction with O-ZIS-120 and desorb as the final product. This study elucidates the topotactic structural transitions of 2D materials simultaneously with electronic structure modulation for efficient photocatalytic DFF production.     

Pt–Cu Interaction Induced Construction of Single Pt Sites for Synchronous Electron Capture and Transfer in Photocatalysis

Single-atom photocatalysts have shown their fascinating strengths in enhancing charge transfer dynamics; however, rationally designing coordination sites by metal doping to stabilize isolated atoms is still challenging. Here, a one-unit-cell ZnIn₂S₄ (ZIS) nanosheet with abundant Cu dopants serving as the suitable support to achieve a single atom Pt catalyst (Pt₁/Cu–ZIS) is reported, and hence the metal single atom–metal dopant interaction at an atomic level is disclosed. Experimental results and density functional theory calculations highlight the unique stabilizing effect (Pt–Cu interaction) of single Pt atoms in Cu-doped ZIS, while apparent Pt clusters are observed in pristine ZIS. Specifically, Pt–Cu interaction provides an extra coordination site except three S sites on the surface, which induces a higher diffusion barrier and makes the single atom more stable on the surface. Apart from stabilizing Pt single atoms, Pt–Cu interaction also serves as the efficient channel to transfer electrons from Cu trap states to Pt active sites, thereby enhancing the charge separation and transfer efficiency. Remarkably, the Pt₁/Cu–ZIS exhibits a superb activity, giving a photocatalytic hydrogen evolution rate of 5.02 mmol g⁻¹ h⁻¹, nearly 49 times higher than that of pristine ZIS.     

Single Semi-Metallic Selenium Atoms on Ti3C2 MXene Nanosheets as Excellent Cathode for Lithium–Oxygen Batteries

Rechargeable Li–O₂ batteries are promising due to their superior high energy density but subject to sluggish oxygen reduction/evolution kinetics. Developing highly efficient catalysts to improve catalytic activity and alleviate oxidation–reduction overpotential of Li–O₂ batteries is of great challenge and importance. Herein, a CO₂-assisted thermal-reaction strategy is developed to fabricate isolated semi-metallic selenium single-atom-doped Ti₃C₂ MXene catalyst (SASe-Ti₃C₂) as cathodes for high-performance Li–O₂ batteries. The isolated moieties of single Se atom catalysis centers can function as active catalytic centers to drastically enhance the intrinsic LiO₂-absorption ability and thus fundamentally modulate the formation/decomposition mechanism of lithium peroxide (Li₂O₂) discharge product, thus demonstrating greatly enhanced redox kinetics and efficiently ameliorated overpotentials. Theoretical simulations reveal that the interaction between Se-involved moieties and Ti₃C₂ substrate greatly enhances the intrinsic LiO₂-absorption ability and fundamentally promotes the charge transfer between electrode and Li₂O₂ product, deeply ameliorating the round-trip overpotential. The well-designed SASe–Ti₃C₂ electrode exhibits decreased charge/discharge polarization (1.10 V vs Li/Li⁺), ultrahigh discharge capacity (17 260 mAh g⁻¹ at 100 mA g⁻¹), and superior durability (170 cycles at 200 mA g⁻¹) as cathode for Li–O₂ batteries. The promising results will shed light on the design of highly efficient catalysts for oxygen-involved systems of future investigation.     

Transformation of Organonitrogen-Encapsulated MOFs into N-Doped Fe3O4@C Nanopolyhedron via CVD Super-Assembly for Photochemical Oxidation

Development of nano-structured metal oxides/heteroatom composites with controlled components and structure for photochemical oxidation still remains a great challenge. Here, a new and versatile strategy is reported for transformation of organonitrogen-encapsulated metal-organic frameworks (MOFs) into N-doped Fe₃O₄@C nanopolyhedron by chemical vapor deposition-induced super-assembly method. Strong confined interaction between organonitrogen guests (urea, thiourea, melamine, and dimethylimidazole) and Fe nodes of MOFs realizes reconstruction of crystal structure and introduction of N species. With the novel approach, the uniform dispersion of guests and perfect metallic/heteroatom interfacial is obtained. Compared with MOFs-derived Fe₂O₃/C, the heteroatom/defect-to-metal cluster charge transfer excitations lead N-doped Fe₃O₄@C to exhibit more superior activity for photocatalytic oxidation (turn-over frequencies as high as 3.72 h⁻¹). It demonstrates that the introduction of abundant pyrrole-N and oxygen vacancies on carbon interface boosts the advance of photo-generated carrier transfer. The study offers a simple and promising strategy for the design of novel metal oxides/heteroatom composite with adjustable structure and functions.     

Manipulating Oxygen Vacancies to Spur Ion Kinetics in V2O5 Structures for Superior Aqueous Zinc-Ion Batteries

Vanadium-based intercalation materials have attracted considerable attention for aqueous zinc-ion batteries (ZIBs). However, the sluggish interlaminar diffusion of zinc ions due to the strong electrostatic interaction, severely restricts their practical application. Herein, oxygen vacancy-enriched V₂O₅ structures (Zn_0.125V₂O₅·0.95H₂O nanoflowers, O_v-ZVO) with expanded interlamellar space and excellent structural stability are prepared for superior ZIBs. In situ electron paramagnetic resonance (EPR) and X-ray diffraction (XRD) characterization revealed that numerous oxygen vacancies are generated at a relatively low reaction temperature because of partially escaped lattice water. In situ spectroscopy and density functional theory (DFT) calculations unraveled that the existence of oxygen vacancies lowered Zn²⁺ diffusion barriers in O_v-ZVO and weakened the interaction between Zn and O atoms, thus contributing to excellent electrochemical performance. The Zn||O_v-ZVO battery displayed a remarkable capacity of 402 mAh g⁻¹ at 0.1 A g⁻¹ and impressive energy output of 193 Wh kg⁻¹ at 2673 W kg⁻¹. As a proof of concept, the Zn||O_v-ZVO pouch cell can reach a high capacity of 350 mAh g⁻¹ at 0.5 A g⁻¹, demonstrating its enormous potential for practical application. This study provides fundamental insights into formation of oxygen-vacant nanostructures and generated oxygen vacancies improving electrochemical performance, directing new pathways toward defect-functionalized advanced materials.     

Synthesis and semiconducting properties of Na2MnPO4F. Application to degradation of Rhodamine B under UV-light

Na₂MnPO₄F is synthesized by hydrothermal route at 453 K and the physical properties and photo-electrochemical characterizations are reported. The compound crystallizes in a monoclinic system (SG: P 2₁/n) with the lattice constants: a=13.7132 Å, b=5.3461 Å, c=13.7079 Å, β=119.97°. The UV–visible spectroscopy shows an indirect optical transition at 2.68 eV; a further direct transition occurs at 3.70 eV, due to the charge transfer O²⁻: 2p → Mn²⁺: e_g. The thermal variation of the electrical conductivity is characteristic of a semiconducting behavior with activation energy of 39 meV and an electron mobility (µ_318 K=5.56×10⁻⁴ cm² V⁻¹ s⁻¹), thermally activated. The flat band potential (+0.47 V_SCE) indicates that the valence band derives mainly from O²⁻: 2p orbital with a small admixture of F⁻ character while the conduction band is made up of Mn²⁺: t_2g orbital. The electrochemical impedance spectroscopy shows the contribution of both the bulk and grains boundaries. The photocatalytic performance of Na₂MnPO₄F for the degradation of Rhodamine B (RhB) is demonstrated on the basis of the energy diagram. 88% of the initial concentration is degraded under UV light and the oxidation follows a first order kinetic with a rate constant of 0.516 h⁻¹. Neither adsorption nor photolysis is observed. The photoactivity results from the electron transition from the hybridized band (O²⁻, F⁻) to the Mn²⁺: e_g orbital, occurring in the UV region. The catalyst was subjected to three successive photocatalytic cycles, thus proving its long term stability.     

Accessible Li Percolation and Extended Oxygen Oxidation Boundary in Rocksalt-like Cathode Enabled by Initial Li-deficient Nanostructure

Disordered rocksalt cathodes have shown attractive electrochemical performance via oxygen redox, but are limited by a necessary Li-excess level above the percolation threshold (x > 1.09 in Li_xTM_2-xO₂, TM = transition metals) to obtain electrochemical activity. However, a relatively low-Li content is essential to alleviate excessive oxygen charge compensation in rocksalt oxides. Herein, taking the homogeneous Li₂MnO₃ and LiMn₂O₄ as the starting point, disordered rocksalt-like cathodes are prepared with initial Li-deficient nanostructures, cation vacancies, and partial spinel-type structures that provide a solution for the acquisition of fast Li⁺ percolation channels under Li-deficient condition. As a result, the prepared sample exhibits high initial discharge capacity (363 mAh g⁻¹) and energy density (1081 Wh kg⁻¹). Advanced spectroscopy and in situ measurements observe highly reversible charge compensation during electrochemical process and assign coupled Mn- and O-related redox contribution. Theoretical calculations also suggest the novel and chemical reversible trapped molecular O₂ model in the rocksalt structure with vacancies, demonstrating a dual role of Li-deficient structure in promoting cationic oxidation and extending reversible oxygen redox boundary. This work is expected to breakthrough the existing ideas of oxygen oxidation and opens up a higher degree of freedom in the design of disordered rocksalt structures.     

Integrating Energy Band Alignment and Oxygen Vacancies Engineering of TiO2 Anatase/Rutile Homojunction for Kinetics-Enhanced Li–S Batteries

The inferior shuttle effect of intermediate lithium polysulfides and the sluggish kinetics of sulfur redox reaction are two serious puzzles for the application of lithium–sulfur batteries. Herein, energy band alignment is combined with oxygen vacancies engineering to obtain TiO₂ anatase/rutile homojunction (A/R-TiO₂) with effective immobilization and high-efficiency catalytic conversion of polysulfides. Theoretical calculations and experiments reveal that the near perfect energy band alignment in A/R-TiO₂ is conducive to fluent charge transfer and high catalytic activity, while the rich oxygen vacancies are engineered to provide abundant active sites for anchoring and accelerating conversion of soluble polysulfides. As a result, a battery with A/R-TiO₂-modified separator delivers a marked sulfur utilization (1210 mAh g⁻¹ at 0.1 C and 689 mAh g⁻¹ at 1 C, 3.75 mg cm⁻²) and a high capacity retention of 63% over 300 cycles at 0.5 C (3.25 mg cm⁻²). More importantly, the A/R-TiO₂-modified separator endows the pouch cell with a high capacity of 128.5 mAh at 0.05 C with a lean electrolyte/sulfur ratio for practical application (S loading: 4 mg cm⁻²).     

Cu7S4/MxSy (M=Cd,Ni, and Mn) Janus Atomic Junctions for Plasmonic Energy Upconversion Boosted Multi-Functional Photocatalysis

Rational design/synthesis of atomic-level-engineered Janus junctions for sunlight-impelled high-performance photocatalytic generation of clean fuels (e.g., H₂O₂ and H₂) and valuable chemicals are of great significance. Especially, it is appealing but challenging to acquire accurately-engineered Janus atomic junctions (JAJs) for simultaneously realizing the plasmonic energy upconversion with near-infrared (NIR) light and direct Z-scheme charge transfer with visible light. Here, a range of new Cu₇S₄/M_xS_y (M=Cd, Ni, and Mn) JAJs are designed/synthesized via a cation-exchange route using Cu₇S₄ hexagonal nanodisks as templates. All Cu₇S₄/M_xS_y JAJs show apparently-enhanced photocatalytic H₂O₂ evolution compared to Cu₇S₄ in pure water. Notably, optimized Cu₇S₄/CdS (CCS) JAJ exhibits the outstanding H₂O₂ evolution rate (2.93 mmol g⁻¹ h⁻¹) in benzyl alcohol aqueous solution, due to the following factors: i) NIR light-impelled plasmonic energy upconversion induced H₂O₂ evolution, revealed by ultrafast transient absorption spectroscopy; ii) visible-light-driven direct Z-scheme charge migration, confirmed by in situ X-ray photoelectron spectroscopy. Besides, three different reaction pathways for H₂O₂ evolution are disclosed by in situ electron spin resonance spectroscopy and quenching experiments. Finally, CCS JAJ also exhibits super-high rates on H₂ and benzaldehyde co-generation using visible-NIR light or NIR light. This work highlights the significance of atomic-scale interface engineering for solar-to-chemical conversion.     

How to Evaluate and Manipulate Charge Transfer and Photocatalytic Response at Hybrid Nanocarbon–Metal Oxide Interfaces

Nanocarbon–metal oxide hybrids are among the most promising functional materials in many cutting‐edge environmental and energy applications where efficient charge separation and extraction are keys to success. The next level of hybrid structures will be achieved once one learns how to control and tune charge/energy transfer processes at the interfaces. However, little is yet known about the nature and extent of these interfacial dynamics in nanocarbon hybrids. Here a model is designed in which ultrathin dielectric layers (Al₂O₃, ZrO₂) between the hybrid's components (ZnO, TiO₂) and carbon nanotubes allow for evaluating and tuning of interfacial charge transfer over an unusually long distance of at least 50 nm. Surprisingly, the transfer efficiency correlates linearly with the barrier layer thickness, indicating that electron conduction through the barrier layer constitutes the rate‐limiting step. It is also demonstrated that the charge transfer efficiency can be tuned by the type of interlayer and its degree of crystallinity, thus controlling the hybrid's performance in the photocatalytic production of hydrogen. It is believed that this model system will help to understand and decipher the fundamentals regarding interfacial charge and energy transfer in nanocarbon hybrids with the aim to further advance these hybrid structures for a wide range of energy applications.     

Management of Host–Guest Triplet Exciton Distribution for Stable,High-Efficiency,Low Roll-Off Solution-Processed Blue Organic Light-Emitting Diodes by Employing Triplet-Energy-Mediated Hosts

High-quality hosts are indispensable for simultaneously realizing stable, high efficiency, and low roll-off blue solution-processed organic light-emitting diodes (OLEDs). Herein, three solution processable bipolar hosts with successively reduced triplet energies approaching the T₁ state of thermally activated delayed fluorescence (TADF) emitter are developed and evaluated for high-performance blue OLED devices. The smaller T₁ energy gap between host and guest allows the quenching of long-lived triplet excitons to reduce exciton concentration inside the device, and thus suppresses singlet-triplet and triplet-triplet annihilations. Triplet-energy-mediated hosts with high enough T₁ and better charge balance in device facilitate high exciton utilization efficiency and uniform triplet exciton distribution among host and TADF guest. Benefited from these synergetic factors, a high maximum external quantum efficiency (EQE_max) of 20.8%, long operational lifetime (T₅₀ of 398.3 h @ 500 cd m⁻²), and negligible efficiency roll-off (EQE of 20.1% @ 1000 cd m⁻²) are achieved for bluish-green TADF OLEDs. Additionally introducing a narrowband emission multiple-resonance TADF material as terminal emitter to accelerate exciton dynamic and improve exciton utilization, a higher EQE_max of 23.1%, suppressed roll-off and extended lifetime of 456.3 h are achieved for the sky-blue sensitized OLEDs at the same brightness.     

Synthesis of Leaf‐Vein‐Like g‐C3N4 with Tunable Band Structures and Charge Transfer Properties for Selective Photocatalytic H2O2 Evolution

Photocatalytic H₂O₂ evolution through two‐electron oxygen reduction has attracted wide attention as an environmentally friendly strategy compared with the traditional anthraquinone or electrocatalytic method. Herein, a biomimetic leaf‐vein‐like g‐C₃N₄ as an efficient photocatalyst for H₂O₂ evolution is reported, which owns tenable band structure, optimized charge transfer, and selective two‐electron O₂ reduction. The mechanism for the regulation of band structure and charge transfer is well studied by combining experiments and theoretical calculations. The H₂O₂ yield of CN4 (287 µmol h^?1) is about 3.3 times higher than that of pristine CN (87 µmol h^?1), and the apparent quantum yield for H₂O₂ evolution over CN4 reaches 27.8% at 420 nm, which is much higher than that for many other current photocatalysts. This work not only provides a novel strategy for the design of photocatalyst with excellent H₂O₂ evolution efficiency, but also promotes deep understanding for the role of defect and doping sites on photocatalytic activity.     

Metal Single-Site Molecular Complex–MXene Heteroelectrocatalysts Interspersed Graphene Nanonetwork for Efficient Dual-Task of Water Splitting and Metal–Air Batteries

Development of multifunctional electrocatalysts with high efficiency and stability is of great interest in recent energy conversion technologies. Herein, a novel heteroelectrocatalyst of molecular iron complex (Fe_MC)-carbide MXene (Mo₂TiC₂T_x) uniformly embedded in a 3D graphene-based hierarchical network (GrH) is rationally designed. The coexistence of Fe_MC and MXene with their unique interactions triggers optimum electronic properties, rich multiple active sites, and favorite free adsorption energy for excellent trifunctional catalytic activities. Meanwhile, the highly porous GrH effectively promotes a multichannel architecture for charge transfer and gas/ion diffusion to improve stability. Therefore, the Fe_MC–MXene/GrH results in superb performances towards oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The practical tests indicate that Zn/Al–air batteries derived from Fe_MC–MXene/GrH cathodic electrodes produce high power densities of 165.6 and 172.7 mW cm⁻², respectively. Impressively, the liquid-state Zn–air battery delivers excellent cycling stability of over 1100 h. In addition, the alkaline water electrolyzer induces a low cell voltage of 1.55 V at 10 mA cm⁻² and 1.86 V at 0.4 A cm⁻² in 30 wt.% KOH at 80 °C, surpassing recent reports. The achievements suggest an exciting multifunctional electrocatalyst for electrochemical energy applications.     

Tuning the Electronic Bandgap of Graphdiyne by H-Substitution to Promote Interfacial Charge Carrier Separation for Enhanced Photocatalytic Hydrogen Production

Graphdiyne (GDY), which features a highly π-conjugated structure, direct bandgap, and high charge carrier mobility, presents the major requirements for photocatalysis. Up to now, all photocatalytic studies are performed without paying too much attention on the GDY bandgap (1.1 eV at the G₀W₀ many-body theory level). Such a narrow bandgap is not suitable for the band alignment between GDY and other semiconductors, making it difficult to achieve efficient photogenerated charge carrier separation. Herein, for the first time, it is demonstrated that tuning the electronic bandgap of GDY via H-substitution (H-GDY) promotes interfacial charge separation and improves photocatalytic H₂ evolution. The H-GDY exhibits an increased bandgap energy ( ≈ 2.5 eV) and exploitable conduction band minimum and valence band maximum edges. As a representative semiconductor, TiO₂ is hybridized with both H-GDY and GDY to fabricate a heterojunction. Compared to the GDY/TiO₂, the H-GDY/TiO₂ heterojunction leads to a remarkable enhancement of the photocatalytic H₂ generation by 1.35 times under UV–visible illumination (6200 µ mol h⁻¹ g⁻¹) and four times under visible light (670 µ mol h⁻¹ g⁻¹). Such enhancement is attributed to the suitable band alignment between H-GDY and TiO₂, which efficiently promotes the photogenerated electron and hole separation, as supported by density functional theory calculations.     

Tailoring Interfacial Charge Transfer for Optimizing Thermoelectric Performances of MnTe-Sb2Te3 Superlattice-Like Films

Interfacial charge transfer has a vital role in tailoring the thermoelectric performance of superlattices (SLs), which, however, is rarely clarified by experiments. Herein, based on epitaxially grown p-type (MnTe)_x(Sb₂Te₃)_y superlattice-like films, synergistically optimized thermoelectric parameters of carrier density, carrier mobility, and Seebeck coefficient are achieved by introducing interfacial charge transfer, in which effects of hole injection, modulation doping, and energy filtering are involved. Carrier transport measurements and angle-resolved photoemission spectroscopy (ARPES) characterizations reveal a strong hole injection from the MnTe layer to the Sb₂Te₃ layer in the SLs, originating from the work function difference between MnTe and Sb₂Te₃. By reducing the thickness of MnTe less than one monolayer, all electronic transport parameters are synergistically optimized in the quantum-dots (MnTe)_x(Sb₂Te₃)₁₂ superlattice-like films, leading to much improved thermoelectric power factors (PFs). The (MnTe)_0.1(Sb₂Te₃)₁₂ obtains the highest room-temperature PF of 2.50 mWm⁻¹K⁻², while the (MnTe)_0.25(Sb₂Te₃)₁₂ possesses the highest PF of 2.79 mWm⁻¹K⁻² at 381 K, remarkably superior to the values acquired in binary MnTe and Sb₂Te₃ films. This research provides valuable guidance on understanding and rationally tailoring the interfacial charge transfer of thermoelectric SLs to further enhance thermoelectric performances.