Tuning Structural and Electronic Configuration of FeN_(4) via External S for Enhanced Oxygen Reduction Reaction

The Fe-N-C material represents an attractive oxygen reduction reaction electrocatalyst,and the FeN_(4)moiety has been identified as a very competitive catalytic active site.Fine tuning of the coordination structure of FeN_(4)has an essential impact on the catalytic performance.Herein,we construct a sulfur-modified Fe-N-C catalyst with controllable local coordination environment,where the Fe is coordinated with four in-plane N and an axial external S.The external S atom affects not only the electron distribution but also the spin state of Fe in the FeN_(4)active site.The appearance of higher valence states and spin states for Fe demonstrates the increase in unpaired electrons.With the above characteristics,the adsorption and desorption of the reactants at FeN_(4)active sites are optimized,thus promoting the oxygen reduction reaction activity.This work explores the key point in electronic configuration and coordination environment tuning of FeN_(4)through S doping and provides new insight into the construction of M-N-C-based oxygen reduction reaction catalysts.

Human blood plasma-based electronic integrated circuit amplifier configuration

Dear Editor： There is accumulating evidence that human blood electronic circuit components and their application circuits become more and more important to cyborg implant/engineering, man-machine interface, hu- man disease detection and healing, and artificial brain evolutionusl. Here, we report the first development of human plasma-based amplifier circuit in the dis- crete as well as integrated circuit （IC） configuration mode. Electrolytes in the human blood contain an enormous number of charge carriers such as positive and negative molecule/atom ions, which are electri- cally conducting media and therefore can be utilized for developing electronic circuit components and their application circuits. These electronic circuits obvi- ously have very high application impact potential towards bio-medical engineering and medical science and technology.

Electronic States of Difluorocarbene Calculated by Multireference Configuration Interaction Method

We investigate the geometries and energies of seven electronic states X-1A1, A1B1, a-3B1, B-1A2,b-3A2, C1B2 and c-3B2 of CF2 carbene using internally contracted multireference configuration interaction methods including Davidson correction （icMRCIq-Q） with different basis sets aug-cc-pVXZ （X=T, Q, 5）. For the first time, the potential energy curves of electronic states of CF2 related icMRCI＋Q/aug-cc-pVTZ level. The ab initio results will and dynamics of electronic states of CF2 radical. to the lowest dissociation limit are calculated at the further increase our understanding of the structures

Relative Irradiance Measurement and Bonding Configurations of Amorphous Fluorinated Carbon Films Deposited by Electron Cyclotron Resonance Plasma

a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of a-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that a-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.

Unveiling the geometric site dependent activity of spinel Co_(3)O_(4)for electrocatalytic chlorine evolution reaction

Spinel cobalt oxide(Co_(3)O_(4)),consisting of tetrahedral Co^(2+)(CoTd)and octahedral Co^(3+)(CoOh),is considered as promising earth-abundant electrocatalyst for chlorine evolution reaction(CER).Identifying the catalytic contribution of geometric Co site in the electrocatalytic CER plays a pivotal role to precisely modulate electronic configuration of active Co sites to boost CER.Herein,combining density functional theory calculations and experiment results assisted with operando analysis,we found that the Co_(Oh) site acts as the main active site for CER in spinel Co_(3)O_(4),which shows better Cl^(-)adsorption and more moderate intermediate adsorption toward CER than CoTd site,and does not undergo redox transition under CER condition at applied potentials.Guided by above findings,the oxygen vacancies were further introduced into the Co_(3)O_(4) to precisely manipulate the electronic configuration of Co_(Oh) to boost Cl^(-)adsorption and optimize the reaction path of CER and thus to enhance the intrinsic CER activity significantly.Our work figures out the importance of geometric configuration dependent CER activity,shedding light on the rational design of advanced electrocatalysts from geometric configuration optimization at the atomic level.

Alternative lead-free mixed-valence double perovskites for high-efficiency photovoltaic applications

Lead-based organic-inorganic hybrid perovskites have exhibited great potential in photovoltaics,achieving power conversion efficiencies(PCEs) exceeding 25%.However,the toxicity of lead and the instability of these materials under moist conditions pose significant barriers to large-scale production.To overcome these limitations,researchers have proposed mixed-valence double perovskites,where Cs_(2)Au~ⅠAu~ⅢI_6 is a particularly effective absorber due to its suitable band gap and high absorptance efficiency.To further extend the scope of these lead-free materials,we varied the trivalent gold ion and halogen anion in Cs_(2)Au~ⅠAu~ⅢI_6,resulting in 18 new structures with unique properties.Further,using first-principles calculations and elimination criteria,we identified four materials with ideal band gaps,small effective carrier mass,and strong anisotropic optical properties.According to theoretical modeling,Cs_(2)AuSbCl_6,Cs_(2)AuInCl_6,and Cs_(2)AuBiCl_6 are potential candidates for solar cell absorbers,with a spectroscopic limited maximum efficiency(SLME) of approximately 30% in a 0.25 μm-thick film.These three compounds have not been previously reported,and therefore,our work provides new insights into potential materials for solar energy conversion.We aim for this theoretical exploration of novel perovskites to guide future experiments and accelerate the development of high-performance photovoltaic devices.

Electron and configuration engineering of atomic Cu and multioxidated Cu_(2+1)O centers via gasifiable reductant strategy for efficient oxygen reduction toward Zn-air battery

Efforts in a large number of transition metal-carbon systems are devoted to the development of efficient catalysts for oxygen reduction reaction(ORR).However,unsatisfied O_(2)adsorption and slow reduction of OH*at the active centers hinder the further development of these catalysts.We here report a gasifiable reductant strategy,of which a new Cu-based metal organic framework(MOF:termed NTU-83)nanosheet was co-pyrolyzed with melamine to produce the N-coordinated atomic Cu and multi-oxidated Cu_(2+1)O active centers on the carbon foam with ultrathin skeleton.The engineered electrons and configuration of the active centers boost the catalyst(Cu/NC-1000)to show superior ORR activity(E_(1/2)=0.85 V),excellent stability,and methanol resistance.Further modeling calculation and controlled experiments reveal that the Cu_(2+1)O species play a crucial role in kinetically accelerated adsorption and activation of O_(2),while the N_(4)coordinated atomic Cu facilitates fast reduction of OH*.Such characteristics endow the Zn-air battery that containing Cu/NC-1000 as air cathode to show a high peak power density(138 mW·cm^(−2)),a high specific capacity of 763 mAh·gZn^(−1),and outstanding long-term cycle stability.The plausible mechanism and excellent performance show that gasifiable reductant strategy opens up a new route for regulation of the electronic of active sites but also provides a candidate for the practical application in energy conversion/storage devices.

In-situ reconstruction of catalysts in cathodic electrocatalysis: New insights into active-site structures and working mechanisms

Cathodic electrocatalytic reactions, such as hydrogen evolution and CO_(2)/N_(2) reduction, are the key processes that store intermittent electricity into stable chemical energy. Although a great progress has been made to boost activity and selectivity via elaborative catalyst design, the structure–property relationships have not been sufficiently understood in the context of surface reconfiguration under working conditions. Recent efforts devoted to tracking dynamic evolution of electrocatalysts using in-situ and/or operando techniques gave new insights into the real structure and working mechanism of active sites,and provided principles to design better catalysts. The achievement of cathodic electrocatalysts in this subject is herein summarized, focusing on the correlations between reconstructed surface and electrocatalytic performance. Briefly, the thermodynamics of reconstruction at cathodes is discussed at first, and then the representative progresses in H_(2) evolution and CO_(2)/N_(2) reduction are introduced in sequence to acquire insights into electrochemical processes on in-situ reconfigured surfaces or interfaces. Finally, a perspective is offered to guide future investigations. This review is anticipated to shed some new light on in-depth understanding cathodic electrocatalysis and exploiting prominent electrocatalysts.

Absolute configuration of Buagafuran:An experimental and theoretical electronic circular dichroism study

Buagafuran is a novel drug candidate derived from natural product.Its absolute configuration has been confirmed by electronic circular dichroism combined with modern quantum-chemical calculation using time-dependent density functional theory.The predicted UV absorbance peak is underestimated by several nanometers compared with the experimental data.The applicability of empirical rule for the C=C-C-O system in Buagafuran has also been discussed.Our results show that electronic circular dichroism could be a useful tool for the absolute configuration assignment of chiral drugs,especially for the oily or semisolid substances,whose crystal structures are impossible to obtain.

SOLUTION BEHAVIOUR OF VARIOUS ALLOYING ELEMENTS IN Ni_3Si

The solid solubilities of 15 common alloying elements added to the Ll_2-type intermetallic compound Ni_3Si at 900°C have been estimated,and their substitution modes have been de- duced from the direction of solubility lobe of the compound.It is shown that the alloying behaviours in Ni_3Si are determined by both size and electronic factors,i.e.,the substitution mode is governed by electronic configuration and solubility by the both.An interaction parameter is presented to describe quantitatively the influence of electronic configuration on substitution mode and the solubility limit can be successfully explained together with atom radius.

Photochemistry of endo and exo electronic configurations of biphenylyl methyl propanal

Both direct and sensitized irradiations of the endo title compound lead to a decarbony- lation product,4-isopropylbiphenyl,via Norrish Type 1 reaction,while the exo isomer gives a carbene intermediate and subsequently formaldehyde 2-biphenylyl isopropyl hemiacetal,which in turn gradually decomposes to dimethyl phenylbenzyl alcohol at room temperature.The triplet pathway dominates the photoreaction of the exo isomer.The singlet and triplet lifetimes of the reactant are found to be 0.29 ns and 5.4μs,respectively.~3(n,π~*),~1(n,π~*),~3(π,π~*)electronic configurations of the exo isomer and ~3(π,π~*)of the endo isomer are photochemically active,but ~1(π,π~*)of the endo isomer shows indirect photoreactivity.

Individually-atomic governing d-π*orbital interactions via Cupromoted optimization of Fe-d band centers for high-efficiency zinc-air battery

It is challenging for precise governing of electronic configuration of the individually-atomic catalysts toward optimal electrocatalysis,as d-band configuration of a metal center determines the adsorption behavior of reactive species to the center in oxygen reduction reaction(ORR).The addition of Cu atom modifies the d-band center position of Fe central atom,thus strengthening the d-π*orbital interactions.Herein,FeCu-NC catalyst in the nitrogen-doped carbon(NC)support containing individual dual-metal CuN4/FeN4 sites was prepared by the surface confinement strategy of zeolitic imidazolate framework(ZIF),treated as a model catalyst.Experimentally and theoretically co-verified dual-metal CuN4/FeN4 sites highly dispersed in the NC support,enable transferring more electrons from FeN4 sites to*OH intermediates,thereby accelerating the desorption process of*OH species.Superior to those commercial Pt/C,Our FeCu-NC catalyst exhibited extraordinary ORR activity(with a E1/2 as high as 0.87 V)and cycling stability in 0.1 M KOH electrolyte,and thereof demonstrated excellent discharge performance in zinc-air batteries.Our construction of dual-atom catalysts(DACs)provides a strategy for atom-by-atom designing high-efficiency catalysts via orbital regulation.