Unfolding B?O?B Bonds for an Enhanced ORR Performance in ABO3‐Type Perovskites

Identifying the relationship between catalytic performance and material structure is crucial to establish the design principle for highly active catalysts. Deficiency in B? O bond covalency induced by lattice distortion severely restricts the oxygen reduction reaction (ORR) performance for ABO₃‐type perovskite oxides. Herein, a rearrangement of hybridization mode for B? O bond is used to tune the overlap of the electron cloud between B 3d and O 2p through A‐stie doping with larger radius ions. The B? O bond covalency is strengthened with a B? O? B bond angle recovered from intrinsic structural distortion. As a result, the adsorption and the reduction process for O₂ on the oxide surface can be promoted via shifting the O‐2p band center toward the Fermi Level. Simultaneously, the spin electrons in the Mn 3d orbit become more parallel. It will lead to a high electrical conductivity by the enhanced double exchange process and thereof mitigate the ORR efficiency loss. Further density functional theory calculation reveals that a flat [BO₂] plane will make contribution to the charge transfer process from lattice oxygen to adsorbed oxygen (mediated with B ions). Through such exploration of the effect of crystal structure on the electronic state of perovskite oxides, a novel insight into design of highly active ORR catalysts is offered.     

B?N Pairs Enriched Defective Carbon Nanosheets for Ammonia Synthesis with High Efficiency

Electrochemical synthesis has garnered attention as a promising alternative to the traditional Haber–Bosch process to enable the generation of ammonia (NH₃) under ambient conditions. Current electrocatalysts for the nitrogen reduction reaction (NRR) to produce NH₃ are comprised of noble metals or transitional metals. Here, an efficient metal‐free catalyst (BCN) is demonstrated without precious component and can be easily fabricated by pyrolysis of organic precursor. Both theoretical calculations and experiments confirm that the doped B? N pairs are the active triggers and the edge carbon atoms near to B? N pairs are the active sites toward the NRR. This doping strategy can provide sufficient active sites while retarding the competing hydrogen evolution reaction (HER) process; thus, NRR with high NH₃ formation rate (7.75 µg h^?1 mg_cat. ^?1) and excellent Faradaic efficiency (13.79%) are achieved at ?0.3 V versus reversible hydrogen electrode (RHE), exceeding the performance of most of the metallic catalysts.     

Cu?Zr?Al?Ti Bulk Metallic Glass with Enhanced Glass‐Forming Ability,Mechanical Properties,Corrosion Resistance and Biocompatibility

The effect of titanium addition on the glass forming ability (GFA), plasticity, corrosion resistance and biocompatibility of Cu? Zr? Al alloy are evaluated by XRD, DSC, compression tests, corrosion, and cytotoxicity tests. The GFA of Cu₄₅Zr₄₈Al₇ amorphous alloy is greatly improved by titanium addition, as evidenced by the increase of critical size from less than 8 mm for Cu₄₅Zr₄₈Al₇ alloy to 10 mm for Cu₄₅Zr_46.5Al₇Ti_1.5 alloy when the samples are prepared by copper mold casting. Cu₄₅Zr_46.5Al₇Ti_1.5 alloy shows enhanced plastic strain up to 10%, good corrosion resistance and biocompatibility in comparison to Cu₄₅Zr₄₈Al₇ alloy.     

Controlling Hot Charge Carrier Transfer in Monolithic Al?Si?Al Heterostructures for Plasmonic On-Chip Energy Harvesting

The generation of hot carriers by Landau damping or chemical interface damping of plasmons is of particular interest to the fundamental aspects of extreme light-matter interactions. Hot charge carriers can be transferred to an attached acceptor for photochemical or photovoltaic energy conversion. However, these lose their excess energy and relax to thermal equilibrium within picoseconds and it is difficult to extract useful work thereof with thermodynamic efficiencies that are of interest for practical devices. Without a detailed understanding of the underlying plasmon decay processes and transfer mechanisms, proper material matching and design considerations for novel plasmonic devices are extremely challenging. Here, a multifunctional Al Si Al heterostructure device with tunable Schottky barriers is presented to control plasmon-induced hot carrier injection at an abrupt metal-semiconductor interface. Light absorption, surface plasmon generation, and separation of hot carriers arising from the non-radiative decay of surface plasmons are realized in a monolithic Schottky barrier field effect transistor. Aside from barrier modulation, a virtual p–n junction can be emulated in the semiconductor channel with the distinct merit that carrier concentration and polarity are tunable by electrostatic gating. The investigations are carried out with a view to possible use for CMOS-compatible plasmonic photovoltaics, with versatile implementations for autonomous nanosystems.     

Replacing C?C Unit with B←N Unit in Isoelectronic Conjugated Polymers for Enhanced Photocatalytic Hydrogen Evolution

Three linear isoelectronic conjugated polymers PCC , PBC , and PBN are synthesized by Suzuki-Miyaura polycondensation for photocatalytic hydrogen (H₂) production from water. PBN presented an excellent photocatalytic hydrogen evolution rate (HER) of 223.5 µmol h⁻¹ (AQY₄₂₀ = 23.3%) under visible light irradiation, which is 7 times that of PBC and 31 times that of PCC . The enhanced photocatalytic activity of PBN is due to the improved charge separation and transport of photo-induced electrons/holes originating from the lower exciton binding energy (E_b), longer fluorescence lifetime, and stronger built-in electric field, caused by the introduction of the polar B←N unit into the polymer backbone. Moreover, the extension of the visible light absorption region and the enhancement of surface catalytic ability further increase the activity of PBN . This work reveals the potential of B←N fused structures as building blocks as well as proposes a rational design strategy for achieving high photocatalytic performance.     

A Robust n-n Heterojunction: Cu?N and B?N Boosting for Ambient Electrocatalytic Nitrogen Reduction to Ammonia

An n-n type heterojunction comprising with Cu N and B N dual active sites is synthesized via in situ growth of a conductive metal–organic framework (MOF) [Cu₃(HITP)₂] (HITP = 2,3,6,7,10,11-hexaiminotriphenylene) on hexagonal boron nitride (h-BN) nanosheets (hereafter denoted as Cu₃(HITP)₂@h-BN) for the electrocatalytic nitrogen reduction reaction (eNRR). The optimized Cu₃(HITP)₂@h-BN shows the outstanding eNRR performance with the NH₃ production of 146.2 µg h⁻¹ mg_cat⁻¹ and the Faraday efficiency of 42.5% due to high porosity, abundant oxygen vacancies, and Cu N/B N dual active sites. The construction of the n-n heterojunction efficiently modulates the state density of active metal sites toward the Fermi level, facilitating the charge transfer at the interface between the catalyst and reactant intermediates. Additionally, the pathway of NH₃ production catalyzed by the Cu₃(HITP)₂@h-BN heterojunction is illustrated by in situ FT-IR spectroscopy and density functional theory calculation. This work presents an alternative approach to design advanced electrocatalysts based on conductive MOFs.     

Engineering C?S?Fe Bond Confinement Effect to Stabilize Metallic-Phase Sulfide for High Power Density Sodium-Ion Batteries (Small 37/2023)

Metallic-phase iron sulfide (e.g., Fe₇S₈) is a promising candidate for high power density sodium storage anode due to the inherent metal electronic conductivity and unhindered sodium-ion diffusion kinetics. Nevertheless, long-cycle stability can not be achieved simultaneously while designing a fast-charging Fe₇S₈-based anode. Herein, Fe₇S₈ encapsulated in carbon-sulfur bonds doped hollow carbon fibers (NHCFs-S-Fe₇S₈) is designed and synthesized for sodium-ion storage. The NHCFs-S-Fe₇S₈ including metallic-phase Fe₇S₈ embrace higher electron specific conductivity, electrochemical reversibility, and fast sodium-ion diffusion. Moreover, the carbonaceous fibers with polar C S Fe bonds of NHCFs-S-Fe₇S₈ exhibit a fixed confinement effect for electrochemical conversion intermediates contributing to long cycle life. In conclusion, combined with theoretical study and experimental analysis, the multinomial optimized NHCFs-S-Fe₇S₈ is demonstrated to integrate a suitable structure for higher capacity, fast charging, and longer cycle life. The full cell shows a power density of 1639.6 W kg⁻¹ and an energy density of 204.5 Wh kg⁻¹, respectively, over 120 long cycles of stability at 1.1 A g⁻¹. The underlying mechanism of metal sulfide structure engineering is revealed by in-depth analysis, which provides constructive guidance for designing the next generation of durable high-power density sodium storage anodes.     

Ambipolar Conjugated Polymers with Ultrahigh Balanced Hole and Electron Mobility for Printed Organic Complementary Logic via a Two‐Step C?H Activation Strategy

High mobility ambipolar conjugated polymers are seriously absent regardless their great potential for flexible and printed plastic devices and circuits. Here, ambipolar polymers with ultrahigh balanced hole and electron mobility are developed via a two‐step C? H activation strategy. Diketopyrrolopyrrole‐benzothiadiazole‐diketopyrrolopyrrole (DBD) and its copolymers with thiophene/selenophene units (short as PDBD‐T and PDBD‐Se) are used as examples. PDBD‐Se exhibits highly efficient ambipolar transport with hole and electron mobility up to 8.90 and 7.71 cm² V^?1 s^?1 in flexible organic field‐effect transistors, presenting a milestone for ambipolar copolymer screening. Based on this performance metrics and good solubility, PDBD‐Se is investigated as inkjet‐printable semiconductor ink for organic complementary logic circuits. Under ambient processing, maximum hole and electron mobilities reach 6.70 and 4.30 cm² V^?1 s^?1, respectively. Printed complementary inverter and NAND gates with transition voltages near V_DD/2 are fabricated, providing an easy‐handling, general material for printed electronics and logic.     

Anion Exchange Facilitates the In Situ Construction of Bi/Bi?O Interfaces for Enhanced Electrochemical CO2-to-Formate Conversion Over a Wide Potential Window

Electrochemical reduction of CO₂ (CO₂RR) into value-added products is a promising strategy to reduce energy consumption and solve environmental issues. Formic acid/formate is one of the high-value, easy-to-collect, and economically viable products. Herein, the reconstructed Bi₂O₂CO₃ nanosheets (BOC_R NSs) are synthesized by an in situ electrochemical anion exchange strategy from Bi₂O₂SO₄ as a pre-catalyst. The BOC_R NSs achieve a high formate Faradaic efficiency (FE_formate) of 95.7% at −1.1 V versus reversible hydrogen electrode (vs. RHE), and maintain FE_formate above 90% in a wide potential range from −0.8 to −1.5 V in H-cell. The in situ spectroscopic studies reveal that the obtained BOC_R NSs undergo the anion exchange from Bi₂O₂SO₄ to Bi₂O₂CO₃ and further promote the self-reduction to metallic Bi to construct Bi/Bi O active site to facilitate the formation of OCHO^* intermediate. This result demonstrates anion exchange strategy can be used to rational design high performance of the catalysts toward CO₂RR.     

Formation of B?N?C Coordination to Stabilize the Exposed Active Nitrogen Atoms in g‐C3N4 for Dramatically Enhanced Photocatalytic Ammonia Synthesis Performance

It is an important issue that exposed active nitrogen atoms (e.g., edge or amino N atoms) in graphitic carbon nitride (g‐C₃N₄) could participate in ammonia (NH₃) synthesis during the photocatalytic nitrogen reduction reaction (NRR). Herein, the experimental results in this work demonstrate that the exposed active N atoms in g‐C₃N₄ nanosheets can indeed be hydrogenated and contribute to NH₃ synthesis during the visible‐light photocatalytic NRR. However, these exposed N atoms can be firmly stabilized through forming B? N? C coordination by means of B‐doping in g‐C₃N₄ nanosheets (BCN) with a B‐doping content of 13.8 wt%. Moreover, the formed B? N? C coordination in g‐C₃N₄ not only effectively enhances the visible‐light harvesting and suppresses the recombination of photogenerated carriers in g‐C₃N₄, but also acts as the catalytic active site for N₂ adsorption, activation, and hydrogenation. Consequently, the as‐synthesized BCN exhibits high visible‐light‐driven photocatalytic NRR activity, affording an NH₃ yield rate of 313.9 µmol g^?1 h^?1, nearly 10 times of that for pristine g‐C₃N₄. This work would be helpful for designing and developing high‐efficiency metal‐free NRR catalysts for visible‐light‐driven photocatalytic NH₃ synthesis.     

In Vivo Performance and Structural Relaxation of Biodegradable Bone Implants Made from Mg?Zn?Ca Bulk Metallic Glasses

A study of Mg‐based bulk metallic glasses (BMGs) as biodegradable bone implants is presented. The implantation site can affect performance, so the BMGs were evaluated in vivo in rat femurs using µ‐CT scans at various times for more than 90 days. Estimates of H₂ evolution correlate well with previous in vitro studies and bone–implant contact is similar to that for Ti pins. One potential drawback of Mg‐based BMGs in this application is embrittlement due to structural relaxation. Here, relaxation at 20 and 37 °C is examined, and an increase in the characteristic relaxation time, from 10 to 30 days at 20 °C, is observed as Zn increases from 29 to 32 at.%, correlating with dramatically reduced hydrogen evolution.     

Enhanced C?O Functionality on Carbon Papers Ensures Lowering Nucleation Delay of ALD for Ru towards Unprecedented Alkaline HER Activity

The success in lowering the nucleation delay for Atomic Layer Deposition (ALD) of Ru on carbon surfaces is mitigated by constructive pretreatments resulting enhancement of C O functionality. Treatment of the carbon papers (CP) allowed Ru species deposition for minimum number of ALD cycles (25 cycles) with good conformality. The development of electrocatalysts from single atoms to nanoparticles (NPs) on conductive supports with low metal loadings, thus improving performance, is essential in electrocatalysis. For alkaline hydrogen evolution reaction, ALD decorated CPs with Ru exhibit low onset potentials of ≈4.7 mV versus reversable hydrogen electrode (RHE) (at 10 mA cm⁻²) and a high turnover frequency of 1.92 H₂ s⁻¹ at 30 mV versus RHE. The Ru decorated CPs show comparable to higher catalytic activity than of Platinum (Pt) decorated CP also developed by ALD. The current representation of unfamiliar catalytic activities of Ru active centers developed by ALD, pave a bright and sustainable path for energy conversion reactions.     

Constructing Active B?N Sites in Carbon Nanosheets for High-Capacity and Fast Charging Toward Potassium Ion Storage

Nitrogen doping is an effective strategy to improve potassium ion storage of carbon electrodes via the creation of adsorption sites. However, various undesired defects are often uncontrollably generated during the doping process, limiting doping effect on capacity enhancement and deteriorating the electric conductivity. Herein, boron element is additionally introduced to construct 3D interconnected B, N co-doped carbon nanosheets to remedy these adverse effects. This work demonstrates that boron incorporation preferentially converts pyrrolic N species into B N sites with lower adsorption energy barrier, further enhancing the capacity of B, N co-doped carbon. Meanwhile, the electric conductivity is modulated via the conjugation effect between the electron-rich N and electron-deficient B, accelerating the charge-transfer kinetics of potassium ions. The optimized samples deliver a high specific capacity, high rate capability, and long-term cyclic stability (532.1 mAh g⁻¹ at 0.05 A g⁻¹, 162.6 mAh g⁻¹ at 2 A g⁻¹ over 8000 cycles). Furthermore, hybrid capacitors using the B, N co-doped carbon anode deliver a high energy and power density with excellent cycle life. This study demonstrates a promising approach using B N sites for adsorptive capacity and electric conductivity enhancement in carbon materials for electrochemical energy storage applications.     

Porous Carbon Membrane‐Supported Atomically Dispersed Pyrrole‐Type Fe?N4 as Active Sites for Electrochemical Hydrazine Oxidation Reaction

The rational design of catalytically active sites in porous materials is essential in electrocatalysis. Herein, atomically dispersed Fe‐N_x sites supported by hierarchically porous carbon membranes are designed to electrocatalyze the hydrazine oxidation reaction (HzOR), one of the key techniques in electrochemical nitrogen transformation. The high intrinsic catalytic activity of the Fe‐N_x single‐atom catalyst together with the uniquely mixed micro‐/macroporous membrane support positions such an electrode among the best‐known heteroatom‐based carbon anodes for hydrazine fuel cells. Combined with advanced characterization techniques, electrochemical probe experiments, and density functional theory calculation, the pyrrole‐type Fe? N₄ structure is identified as the real catalytic site in HzOR.     

Liberating N‐CNTs Confined Highly Dispersed Co?Nx Sites for Selective Hydrogenation of Quinolines

Selective hydrogenation of quinoline and its derivatives is an important means to produce corresponding 1,2,3,4‐tetrahydroquinolines for a wide spectrum of applications. A facile and efficient “laser irradiation in liquid” technique to liberate the inaccessible highly dispersed Co? N_x active sites confined inside N‐doped carbon nanotubes is demonstrated. The liberated Co? N_x sites possess generic catalytic activities toward selective hydrogenation of quinoline and its hydroxyl, methyl, and halogen substituted derivatives into corresponding 1,2,3,4‐tetrahydroquinolines with almost 100% conversion efficiency and selectivity. This laser irradiation treatment approach should be widely applicable to unlock the catalytic powers of inaccessible catalytic active sites confined by other materials.     

Highly Exposed ?NH2 Edge on Fragmented g-C3N4 Framework with Integrated Molybdenum Atoms for Catalytic CO2 Cycloaddition: DFT and Techno-Economic Assessment

This study focuses on the applicability of single-atom Mo-doped graphitic carbon nitride (GCN) nanosheets which are specifically engineered with high surface area (exfoliated GCN),  NH₂ rich edges, and maximum utilization of isolated atomic Mo for propylene carbonate (PC) production through CO₂ cycloaddition of propylene oxide (PO). Various operational parameters are optimized, for example, temperature (130 °C), pressure (20 bar), catalyst (Mo₂GCN), and catalyst mass (0.1 g). Under optimal conditions, 2% Mo-doped GCN (Mo₂GCN) has the highest catalytic performance, especially the turnover frequency (TOF) obtained, 36.4 h⁻¹ is higher than most reported studies. DFT simulations prove the catalytic performance of Mo₂GCN significantly decreases the activation energy barrier for PO ring-opening from 50–60 to 4.903 kcal mol⁻¹. Coexistence of Lewis acid/base group improves the CO₂ cycloaddition performance by the formation of coordination bond between electron-deficient Mo atom with O atom of PO, while  NH₂ surface group disrupts the stability of CO₂ bond by donating electrons into its low-level empty orbital. Steady-state process simulation of the industrial-scale consumes 4.4 ton h⁻¹ of CO₂ with PC production of 10.2 ton h⁻¹. Techno-economic assessment profit from Mo₂GCN is estimated to be 60.39 million USD year⁻¹ at a catalyst loss rate of 0.01 wt% h⁻¹.