Structural Characteristics, Electronic Properties, and Coupling Behavior of 12-4-12, 12-3-12, 12-2-12 Cationic Surfactants: A First-Principles Computational Investigation and Experimental Raman Spectroscopy.

In this study, we present a comprehensive first-principles computational investigation focused on the structural characteristics, electronic properties, and coupling integrations of three cationic Gemini surfactants: 12-4-12, 12-3-12, and 12-2-12 ((CH3(CH2)11)(CH3)2-N+-(CH2)n-N+(CH3(CH2)11)(CH3)2, where n = 2, 3, or 4). By employing Density Functional Theory (DFT) computations, we aimed to gain insights into the fundamental aspects of these surfactant molecules, and the intermolecular interactions among these surfactant molecules. We examined different conformers of each surfactant, including parallel, wing, and bent conformers, and compared their relative stability and properties. We elucidated that the complex structural characteristics, electronic properties, and molecular arrangements of the surfactants vary according to the number of carbon atoms in the central spacer. We also conducted experimental Raman spectroscopy on the three surfactants to compare the results with our computational findings. Furthermore, we computed the coupling behaviors of different conformers of 12-4-12 surfactants in order to gain insights into their coupling mechanism.

Deciphering the Catalytic Mechanism of Peroxidase-like Activity of Iron Sulfide Nanozymes.

Iron sulfide nanomaterials represented by FeS2 and Fe3S4 nanozymes have attracted increasing attention due to their biocompatibility and peroxidase-like (POD-like) catalytic activity in disease diagnosis and treatments. However, the mechanism responsible for their POD-like activities remains unclear. Herein, taking the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 on FeS2(100) and Fe3S4(001) surfaces, the catalytic mechanism was investigated in detail using density functional theory (DFT) calculations and experimental characterizations. Our experimental results showed that the catalytic activity of FeS2 nanozymes was significantly higher than that of Fe3S4 nanozymes. Our DFT calculations indicated that the surface iron ions of iron sulfide nanozymes could effectively catalyze the production of HO• radicals via the interactions between Fe 3d electrons and the frontier orbitals of H2O2 in the range of -10 to 5 eV. However, FeS2 nanozymes exhibited higher POD-like activity due to the surface Fe(II) binding to H2O2, forming inner-orbital complexes, which results in a larger binding energy and a smaller energy barrier for the base-like decomposition of H2O2. In contrast, the surface iron ions of Fe3S4 nanozymes bind to H2O2, forming outer-orbital complexes, which results in a smaller binding energy and a larger energy barrier for the base-like decomposition of H2O2. The charge transfer analysis showed that FeS2 nanozymes transferred 0.12 e and Fe3S4 nanozymes transferred 0.05 e from their surface iron ions to H2O2, respectively. The simulations were consistent with the experimental observations that the FeS2 nanozymes had a greater affinity for H2O2 compared to that of Fe3S4 nanozymes. This work provides a theoretical foundation for the rational design and accurate preparation of iron sulfide functional nanozymes.

Carbon Corrosion Induced by Surface Defects Accelerates Degradation of Platinum/Graphene Catalysts in Oxygen Reduction Reaction.

Graphene supported electrocatalysts have demonstrated remarkable catalytic performance for oxygen reduction reaction (ORR). However, their durability and cycling performance are greatly limited by Oswald ripening of platinum (Pt) and graphene support corrosion. Moreover, comprehensive studies on the mechanisms of catalysts degradation under 0.6-1.6 V versus RHE (Reversible Hydrogen Electrode) is still lacking. Herein, degradation mechanisms triggered by different defects on graphene supports are investigated by two cycling protocols. In the start-up/shutdown cycling (1.0-1.6 V vs. RHE), carbon oxidation reaction (COR) leads to shedding or swarm-like aggregation of Pt nanoparticles (NPs). Theoretical simulation results show that the expansion of vacancy defects promotes reaction kinetics of the decisive step in COR, reducing its reaction overpotential. While under the load cycling (0.6-1.0 V vs. RHE), oxygen containing defects lead to an elevated content of Pt in its oxidation state which intensifies Oswald ripening of Pt. The presence of vacancy defects can enhance the transfer of electrons from graphene to the Pt surface, reducing the d-band center of Pt and making it more difficult for the oxidation state of platinum to form in the cycling. This work will provide comprehensive understanding on Pt/Graphene catalysts degradation mechanisms.

Density Functional Study of Electrocatalytic Carbon Dioxide Reduction in Fourth-Period Transition Metal-Tetrahydroxyquinone Organic Framework.

This study investigates the utilisation of organometallic network frameworks composed of fourth-period transition metals and tetrahydroxyquinone (THQ) in electrocatalytic CO2 reduction. Density functional theory (DFT) calculations were employed in analysing binding energies, as well as the stabilities of metal atoms within the THQ frameworks, for transition metal TM-THQs ranging from Y to Cd. The findings demonstrate how metal atoms could be effectively dispersed and held within the THQ frameworks due to sufficiently high binding energies. Most TM-THQ frameworks exhibited favourable selectivity towards CO2 reduction, except for Tc and Ru, which experienced competition from hydrogen evolution reaction (HER) and required solution environments with pH values greater than 5.716 and 8.819, respectively, to exhibit CO2RR selectivity. Notably, the primary product of Y, Ag, and Cd was HCOOH; Mo produced HCHO; Pd yielded CO; and Zr, Nb, Tc, Ru, and Rh predominantly generated CH4. Among the studied frameworks, Zr-THQ displayed values of 1.212 V and 1.043 V, corresponding to the highest limiting potential and overpotential, respectively, while other metal-organic frameworks displayed relatively low ranges of overpotentials from 0.179 V to 0.949 V. Consequently, it is predicted that the TM-THQ framework constructed using a fourth-period transition metal and tetrahydroxyquinone exhibits robust electrocatalytic reduction of CO2 catalytic activity.

Tailoring Advanced CdS Anisotropy-Driven Charge Spatial Vectorial Separation and Migration via In Situ Dual Co-Catalyst Synergistic Layout.

Tailoring advanced anisotropy-driven efficient separation and migration of photogenerated carriers is a pivotal stride toward enhancing photocatalytic activity. Here, CdS-MoS2 binary photocatalysts are tailored into a dumbbell shape by leveraging the rod-shaped morphology of CdS and employing an in situ tip-induction strategy. To further enhance the photocatalytic activity, an in situ photo-deposition strategy is incorporated to cultivate MnOx particles on the dumbbell-shaped CdS-MoS2. The in situ deposition of MnOx effectively isolated the oxidatively active sites on the CdS surface, emphasizing the reductively active crystalline face of CdS, specifically the (002) face. Benefiting from its robust activity as a reduction active site, MoS2 adeptly captures photogenerated electrons, facilitating the reduction of H+ to produce hydrogen. The anisotropically driven separation of CdS photogenerated carriers markedly mitigates the Coulomb force or binding force of the photogenerated electrons, thus promoting a smoother migration toward the active site for photocatalytic hydrogen evolution. The hydrogen evolution rate of 35MnOx-CdS-MoS2-3 surpasses that of CdS by nearly an order of magnitude, achieving a quantum efficiency of 22.30% at 450 nm. Under simulated solar irradiation, it attains a rate of 42.86 mmol g-1 h-1. This work imparts valuable insights for the design of dual co-catalysts, anisotropy-driven spatial vectorial charge separation and migration, and the analysis of migration pathways of photogenerated carriers.

Synergy Between Surface Confinement and Heterointerfacial Regulations with Fast Electron/Ion Migration in InSe-PPy for Sodium-Ion Storage.

Layered indium selenide (InSe) is a new 2D semiconductor material with high carrier mobility, widely adjustable bandgap, and high ductility. However, its ion storage behavior and related electrochemical reaction mechanism are rarely reported. In this study, InSe nanoflakes encapsulated in conductive polypyrrole (InSe@PPy) are designed in consideration of restraining the severe volume change in the electrochemical reaction and increasing conductivity via in situ chemical oxidation polymerization. Density functional theory calculations demonstrate that the construction of heterostructure can generate an internal electric field to accelerate electron transfer via additional driving forces, offering synergistically enhanced structural stability, electrical conductivity, and Na+ diffusion process. The resulting InSe@PPy composite shows outstanding electrochemical performance in the sodium ion batteries system, achieving a high reversible capacity of 336.4 mA h g-1 after 500 cycles at 1 A g-1 and a long-term cyclic stability with capacity of 274.4 mA h g-1 after 2800 cycles at 5 A g-1 . In particular, the investigation of capacity fluctuation within the first cycling reveals the alternating significance of intercalation and conversion reactions and evanescent alloying reaction. The combined reaction mechanism of insertion, conversion, and alloying of InSe@PPy is revealed by in situ X-ray diffraction, ex situ electrochemical impedance spectroscopy, and transmission electron microscopy.

Unraveling the Performance Descriptors for Designing Single-Atom Catalysts on Defective MXenes for Exclusive Nitrate-To-Ammonia Electrocatalytic Upcycling.

Electrocatalytic nitrate reduction reaction (NO3 RR) is a promising approach for converting nitrate into environmentally benign or even value-added products such as ammonia (NH3 ) using renewable electricity. However, the poor understanding of the catalytic mechanism on metal-based surface catalysts hinders the development of high-performance NO3 RR catalysts. In this study, the NO3 RR mechanism of single-atom catalysts (SACs) is systematically explored by constructing single transition metal atoms supported on MXene with oxygen vacancies (Ov -MXene) using density functional theory (DFT) calculations. The results indicate that Ag/Ov -MXene (for precious metal) and Cu/Ov -MXene (for non-precious metal) are highly efficient SACs for NO3 RR toward NH3 , with low limiting potentials of -0.24 and -0.34 V, respectively. Furthermore, these catalysts show excellent selectivity toward ammonia due to the high energy barriers associated to the formation of byproducts such as NO2 , NO, N2 O, and N2 on Ag/Ov -MXene and Cu/Ov -MXene, effectively suppressing the competitive hydrogen evolution reaction (HER). The findings not only offer new strategies for promoting NH3 production by MXene-based SACs electrocatalysts under ambient conditions but also provide insights for the development of next-generation NO3 RR electrocatalysts.

Breaking Scaling Relations for Highly Efficient Electroreduction of CO2 to CO on Atomically Dispersed Heteronuclear Dual-Atom Catalyst.

Conversion of CO2 into value-added products by electrocatalysis provides a promising way to mitigate energy and environmental problems. However, it is greatly limited by the scaling relationship between the adsorption strength of intermediates. Herein, Mn and Ni single-atom catalysts, homonuclear dual-atom catalysts (DACs), and heteronuclear DACs are synthesized. Aberration-corrected annular dark-field scanning transmission electron microscopy (ADF-STEM) and X-ray absorption spectroscopy characterization uncovered the existence of the Mn─Ni pair in Mn─Ni DAC. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy reveal that Mn donated electrons to Ni atoms in Mn─Ni DAC. Consequently, Mn─Ni DAC displays the highest CO Faradaic efficiency of 98.7% at -0.7 V versus reversible hydrogen electrode (vs RHE) with CO partial current density of 16.8 mA cm-2. Density functional theory calculations disclose that the scaling relationship between the binding strength of intermediates is broken, resulting in superior performance for ECR to CO over Mn─Ni─NC catalyst.

The Magnesium Insertion Effects into P2-Type Na2/3 Ni1/3 Mn2/3 O2.

A Mg-cell with P2-Na2/3 Ni1/3 Mn2/3 O2 layered oxide cathode provides novel reaction mechanism not observed in Na-cells. The sodium/vacancy ordering and Jahn-Teller effects are suppressed with the insertion of magnesium ion. The Mg-cell exhibits different features when operating between 4.5 and 0.15 V and 3.9 and 0.15 V versus Mg2+ /Mg. To analyze the structural and chemical changes during Mg insertion, the cathode is first charged to obtain the Na1/3 Ni1/3 Mn2/3 O2 compound, which is formally accompanied by an oxidation from Ni2+ to Ni3+ . As structure models Mg1/6 Na1/3 Ni1/3 Mn2/3 O2 and Mg1/12 Na1/2 Ni1/3 Mn2/3 O2 are utilized with a large 2 3 a $2\sqrt 3 a$ × 2 3 a $2\sqrt 3 a$ supercell. On discharge, the Mg-cell exhibits a multistep profile which reaches ≈100 mA h g-1 with the valence change from Ni3+ to Ni2+ . Such profile is quite different from its sodium counterpart (230 mA h g-1 ) which exhibits the sodium/vacancy ordering and deleterious presence of Mn3+ . Depending on how the two interlayer spacings are filled by Na and Mg the "staged," "intermediated," and "average" models are analyzed for Mgy Na8 Ni8 Mn16 O48 supercell. This fact suggests differences in the cell performance when Mg is used as counter electrode providing some tips to improve the structure engineering on cathode materials.

Regulating the Oxygen Vacancy and Electronic Structure of NiCo Layered Double Hydroxides by Molybdenum Doping for High-Power Hybrid Supercapacitors.

Amelioration of nickel-cobalt layered double hydroxides (NiCo-LDH) with a high specific theoretical capacitance is of great desire for high-power supercapacitors. Herein, a molybdenum (Mo) doping strategy is proposed to improve the charge-storage performance of NiCo-LDH nanosheets growing on carbon cloth (CC) via a rapid microwave process. The regulation of the electronic structure and oxygen vacancy of the LDH is consolidated by the density functional theory (DFT) calculation, which demonstrates that Mo doping narrows the band gap, reduces the formation energy of hydroxyl vacancies, and promotes ionic and charge transfer as well as electrolyte adsorption on the electrode surface. The optimal Mo-doped NiCo-LDH electrode (MoNiCo-LDH-0.05/CC) has an amazing specific capacity of 471.1 mA h g-1 at 1 A g-1 , and excellent capacity retention of 84.8% at 32 A g-1 , far superior to NiCo-LDH/CC (258.3 mA h g-1 and 76.4%). The constructed hybrid supercapacitor delivers an energy density of 103.3 W h kg-1 at a power density of 750 W kg-1 and retains the cycle retention of 85.2% after 5000 cycles. Two assembled devices in series can drive thirty LED lamps, revealing a potential application prospect of the rationally synthesized MoNiCo-LDH/CC as an energy-storage electrode material.

BiVO4 Photoanodes Enhanced with Metal Phosphide Co-Catalysts: Relevant Properties to Boost Photoanode Performance.

Achieving highly performant photoanodes for oxygen evolution is key to developing photoelectrochemical devices for solar water splitting. In this work, BiVO4 photoanodes are enhanced with a series of core-shell structured bimetallic nickel-cobalt phosphides (MPs), and key insights into the role of co-catalysts are provided. The best BiVO4 /Ni1.5 Co0.5 P and BiVO4 /Ni0.5 Co1.5 P photoanodes achieve a 3.5-fold increase in photocurrent compared with bare BiVO4 . It is discovered that this enhanced performance arises from a synergy between work function, catalytic activity, and capacitive ability of the MPs. Distribution of relaxation times analysis reveals that the contact between the MPs, BiVO4 , and the electrolyte gives rise to three routes for hole injection into the electrolyte, all of which are significantly improved by the presence of a second metal cation in the co-catalyst. Kinetic studies demonstrate that the significantly improved interfacial charge injection is due to a lower charge-transfer resistance, enhanced oxygen-evolution reaction kinetics, and larger surface hole concentrations, providing deeper insights into the carrier dynamics in these photoanode/co-catalyst systems for their rational design.

Exploration of charge transfer analysis and photovoltaics properties of A-D-A type non-fullerene phenazine based molecules to enhance the organic solar cell properties.

To intensify the photovoltaic properties of organic solar cells, density functional theory (DFT) based computational techniques were implemented on six non-fullerene A-D-A type small molecules (N1-N6) modified from reference molecule (R) which consists of phenazine fused with 1,4- Dimethyl-4H-3,7-dithia-4-aza- cyclopenta [α] pentalene on both sides with one of its phenyl rings acting as the central donor unit, further attached with 2-(5,6-Difluoro-2-methylene-3-oxo-indan-1-ylidene)-malononitrile acceptor groups at terminal sites. All proposed compounds have a phenazine base modified with a variety of substituents at the terminals. Transition density matrix, density of states, frontier molecular orbitals, intramolecular charge transfer abilities and optoelectronic properties of these compounds were investigated using B3LYP/6-31G (d, p) and B3LYP/6-31G++ (d,p) level of theory. All six designed compounds exhibited a bathochromic sift in their λmax as compared to the R molecule. All designed molecules also have reduced band gap and smaller excitation energy than R. Among all, N6 exhibited highest λmax and lowest bandgap as compared to reference molecule indicating its promising photovoltaic properties. Decreased hole and electron reorganization energy in several of the suggested compounds is indicative of greater charge mobility in them. PTB7-Th donor was employed to calculate open circuit voltage of all investigated molecules. N1-N5 molecules had improved optoelectronic properties, significant probable power conversion efficiency as evident from their absorption aspects, high values of Voc, and fill factor, compared to R molecule. Designed A-D-A type NF based molecules make OSCs ideal for use in wearable devices, building-integrated photovoltaics and smart fabrics.

Defect-Mediated Growth of Crystallographic Shear Plane.

As representative extended planar defects, crystallographic shear (CS) planes, namely Wadsley defects, play an important role in modifying the physical and chemical properties of metal oxides. Although these special structures have been intensively investigated for high-rate anode materials and catalysts, it is still experimentally unclear how the CS planes form and propagate at the atomic scale. Here, the CS plane evolution in monoclinic WO3 is directly imaged via in situ scanning transmission electron microscope. It is found that the CS planes nucleate preferentially at the edge step defects and proceed by the cooperative migration of WO6 octahedrons along particular crystallographic orientations, passing through a series of intermediate states. The local reconstruction of atomic columns tends to form (102) CS planes featured with four edge-sharing octahedrons in preference to the (103) planes, which matches well with the theoretical calculations. Associated with the structure evolution, the sample undergoes a semiconductor-to-metal transition. In addition, the controlled growth of CS planes and V-shaped CS structures can be achieved by artificial defects for the first time. These findings enable an atomic-scale understanding of CS structure evolution dynamics.

All-Graphene Quantum Dot-Derived Battery: Regulating Redox Activity Through Localized Subdomains.

In the quest for materials sustainability for grid-scale applications, graphene quantum dot (GQD), prepared via eco-efficient processes, is one of the promising graphitic-organic matters that have the potential to provide greener solutions for replacing metal-based battery electrodes. However, the utilization of GQDs as electroactive materials has been limited; their redox behaviors associated with the electronic bandgap property from the sp2 carbon subdomains, surrounded by functional groups, are yet to be understood. Here, the experimental realization of a subdomained GQD-based anode with stable cyclability over 1000 cycles, combined with theoretical calculations, enables a better understanding of the decisive impact of controlled redox site distributions on battery performance. The GQDs are further employed in cathode as a platform for full utilization of inherent electrochemical activity of bio-inspired redox-active organic motifs, phenoxazine. Using the GQD-derived anode and cathode, an all-GQD battery achieves a high energy density of 290 Wh kgcathode -1 (160 Wh kgcathode+anode -1 ), demonstrating an effective way to improve reaction reversibility and energy density of sustainable, metal-free batteries.

Controlled One-Step Synthesis of MOF-on-MOF Cocatalysts for Two-Channel Electrocatalytic Conversion of CO2 to Formic Acid.

The synthesis of efficient and highly selective catalysts and rational reactor design play decisive roles in the industrial application of the electrocatalytic carbon dioxide reduction reaction (CO2 RR). In this study, a dual-metal-organic framework (MOF) copper-based catalytic electrode is designed and prepared in one step by in situ synthesis on a foamed copper substrate. The MOF-on-MOF structure can effectively inhibit the generation of H2 and CO, and further enhance the selectivity of HCOOH. Furthermore, by using cheap and durable poly(tetrafluoroethylene) (PTFE) instead of an expensive and fragile GDE, the optimized reactor design improves the stability and durability of the gas channel and the replaceability of the electrode. The structure-optimized reactor has a maximum Faradaic efficiency of 89.2% in neutral medium, and an average current density of 26.1 mA cm-2 in the flow cell, which has comparable performance to a GDE and can continue to operate stably. The use of PTFE improves the service life of the gas mass transfer channel, and the independent catalytic electrode can provide good catalytic efficiency. These results provide new insights into the reaction mechanism of structurally recombined double MOFs and PTFE-optimized CO2 RR reactor designs, providing technical support for the practical industrial application of the CO2 RR.

n→π* Electron Transitions and Directional Charge Migration Synergistically Promoting O2 Activation and Holes Utilization on Carbon Nitride for Efficiently Photocatalytic Degradation of Organic Contaminants.

Stimulating electron transitions and promoting exciton dissociation are crucial for improving the photocatalytic performance of polymeric carbon nitride (CN) yet still challenging. Herein, a novel CN with C dopant and asymmetric structure (CC-UCN2 ) is ingeniously synthesized. The obtained CC-UCN2 not only reinforces the intrinsic π→π* electron transitions, but also successfully awakens additional n→π* electron transitions. Besides, charge centers dislocation caused by symmetry breaking induces a spontaneous polarized electric field, effectively breaking the constraints of Coulomb electrostatic interaction between electrons and holes and driving their directional migration. Along with the spatial separation of reduction and oxidation sites, CC-UCN2 shows exceptional O2 activation and holes oxidation efficiency, thus exhibits a high degradation rate constant (0.201 min-1 ) and mineralization rate (80.1%) for bisphenol A (BPA)(far outperforming pristine and other modified CNs). This work proposes a novel perspective for developing high-efficiency photocatalysts and comprehending the underlying mechanism of O2 activation and holes oxidation for pollutant degradation.

A Comparative XPS, UV PES, NEXAFS, and DFT Study of the Electronic Structure of the Salen Ligand in the H2(Salen) Molecule and the [Ni(Salen)] Complex.

A comparative study of the electronic structure of the salen ligand in the H2(Salen) molecule and the [Ni(Salen)] complex was performed using the experimental methods of XPS, UV PES, and NEXAFS spectroscopy along with DFT calculations. Significant chemical shifts of +1.0 eV (carbon), +1.9 eV (nitrogen), and -0.4 eV (oxygen) were observed in the 1s PE spectra of the salen ligand atoms when passing from a molecule to a complex, unambiguously indicating a substantial redistribution of the valence electron density between these atoms. It is proposed that the electron density transfer to the O atoms in [Ni(Salen)] occurred not only from the Ni atom, but also from the N and C atoms. This process seemed to be realized through the delocalized conjugated π-system of the phenol C 2p electronic states of the ligand molecule. The DFT calculations (total and partial DOS) for the valence band H2(Salen) and [Ni(Salen)] described well the spectral shape of the UV PE spectra of both compounds and confirmed their experimental identification. An analysis of the N and O 1s NEXAFS spectra clearly indicated that the atomic structure of the ethylenediamine and phenol fragments was retained upon passing from the free salen ligand to the nickel complex.

2D Cobalt Chalcogenide Heteronanostructures Enable Efficient Alkaline Hydrogen Evolution Reaction.

The development of high-efficiency non-precious metal electrocatalysts for alkaline electrolyte hydrogen evolution reactions (HER) is of great significance in energy conversion to overcome the limited supply of fossil fuels and carbon emission. Here, a highly active electrocatalyst is presented for hydrogen production, consisting of 2D CoSe2 /Co3 S4 heterostructured nanosheets along Co3 O4 nanofibers. The different reaction rate between the ion exchange reaction and redox reaction leads to the heterogeneous volume swelling, promoting the growth of 2D structure. The 2D/1D heteronanostructures enable the improved the electrochemical active area, the number of active sites, and more favorable H binding energy compared to individual cobalt chalcogenides. The roles of the different composition of the heterojunction are investigated, and the electrocatalysts based on the CoSe2 /Co3 S4 @Co3 O4 exhibited an overpotential as low as 165 mV for 10 mA cm-2 and 393 mV for 200 mA cm-2 in 1 m KOH electrolyte. The as-prepared electrocatalysts remained active after 55 h operation without any significant decrease, indicating the excellent long-term operation stability of the electrode. The Faradaic efficiency of hydrogen production is close to 100% at different voltages. This work provides a new design strategy toward Co-based catalysts for efficient alkaline HER.

Synthesis of Bis(amino acids) Containing the Styryl-cyclobutane Core by Photosensitized [2+2]-Cross-cycloaddition of Allylidene-5(4H)-oxazolones.

The irradiation of 2-aryl-4-(E-3'-aryl-allylidene)-5(4H)-oxazolones 1 with blue light (456 nm) in the presence of [Ru(bpy)3](BF4)2 (bpy = 2,2'-bipyridine, 5% mol) gives the unstable cyclobutane-bis(oxazolones) 2 by [2+2]-photocycloaddition of two oxazolones 1. Each oxazolone contributes to the formation of 2 with a different C=C bond, one of them reacting through the exocyclic C=C bond, while the other does so through the styryl group. Treatment of unstable cyclobutanes 2 with NaOMe/MeOH produces the oxazolone ring opening reaction, affording stable styryl-cyclobutane bis(amino acids) 3. The reaction starts with formation of the T1 excited state of the photosensitizer 3[Ru*(bpy)3]2+, which reacts with S0 of oxazolones 1 through energy transfer to give the oxazolone T1 state 3(oxa*)-1, which is the reactive species and was characterized by transient absorption spectroscopy. Measurement of the half-life of 3(oxa*)-1 for 1a, 1b and 1d shows large values for 1a and 1b (10-12 µs), while that of 1d is shorter (726 ns). Density functional theory (DFT) modeling displays strong structural differences in the T1 states of the three oxazolones. Moreover, study of the spin density of T1 state 3(oxa*)-1 provides clues to understanding the different reactivity of 4-allylidene-oxazolones described here with respect to the previously reported 4-arylidene-oxazolones.

Regulated Surface Electronic States of CuNi Nanoparticles through Metal-Support Interaction for Enhanced Electrocatalytic CO2 Reduction to Ethanol.

Developing stable catalysts with higher selectivity and activity within a wide potential range is critical for efficiently converting CO2 to ethanol. Here, the carbon-encapsulated CuNi nanoparticles anchored on nitrogen-doped nanoporous graphene (CuNi@C/N-npG) composite are designedly prepared and display the excellent CO2 reduction performance with the higher ethanol Faradaic effiency (FEethanol  ≥ 60%) in a wide potential window (600 mV). The optimal cathodic energy efficiency (47.6%), Faradaic efficiency (84%), and selectivity (96.6%) are also obtained at -0.78 V versus reversible hydrogen electrode (RHE). Combining with the density functional theory (DFT) calculations, it is demonstrated that the stronger metal-support interaction (Ni-N-C) can regulate the surface electronic structure effectively, boosting the electron transfer and stabilizing the active sites (Cu0 -Cuδ+ ) on the surface of CuNi@C/N-npG, finally realizing the controllable transition of reaction intermediates. This work may guide the designs of electrocatalysts with highly catalytic performance for CO2 reduction to C2+ products.