The prediction of donor number and acceptor number of electrolyte solvent molecules based on machine learning

Electrolyte solvents have a critical impact on the design of high performance and safe batteries.Gutmann's donor number(DN) and acceptor number(AN) values are two important parameters to screen and design superior electrolyte solvents. However, it is more time-consuming and expensive to obtain DN and AN values through experimental measurements. Therefore, it is essential to develop a method to predict DN and AN values. This paper presented the prediction models for DN and AN based on molecular structure descriptors of solvents, using four machine learning algorithms such as Cat Boost(Categorical Boosting), GBRT(Gradient Boosting Regression Tree), RF(Random Forest) and RR(Ridge Regression).The results showed that the DN and AN prediction models based on Cat Boost algorithm possesses satisfactory prediction ability, with R^(2) values of the testing set are 0.860 and 0.96. Moreover, the study analyzed the molecular structure parameters that impact DN and AN. The results indicated that TDB02m(3D Topological distance based descriptors-lag 2 weighted by mass) had a significant effect on DN, while HATS1s(leverage-weighted autocorrelation of lag 1/weighted by I-state) plays an important role in AN. The work provided an efficient approach for accurately predicting DN and AN values, which is useful for screening and designing electrolyte solvents.

Molecular-level proton acceptor boosts oxygen evolution catalysis to enable efficient industrial-scale water splitting

Industrial water splitting has long been suppressed by the sluggish kinetics of the oxygen evolution reaction(OER),which requires a catalyst to be efficient.Herein,we propose a molecular-level proton acceptor strategy to produce an efficient OER catalyst that can boost industrial-scale water splitting.Molecular-level phosphate(-PO_(4))group is introduced to modify the surface of PrBa_(0.5)Ca_(0.5)Co_(2)O_(5)+δ(PBCC).The achieved catalyst(PO_(4)-PBCC)exhibits significantly enhanced catalytic performance in alkaline media.Based on the X-ray absorption spectroscopy results and density functional theory(DFT)calculations,the PO_(4)on the surface,which is regarded as the Lewis base,is the key factor to overcome the kinetic limitation of the proton transfer process during the OER.The use of the catalyst in a membrane electrode assembly(MEA)is further evaluated for industrial-scale water splitting,and it only needs a low voltage of 1.66 V to achieve a large current density of 1 A cm^(-2).This work provides a new molecular-level strategy to develop highly efficient OER electrocatalysts for industrial applications.

Novel donor-acceptor-donor structured small molecular hole transporting materials for planar perovskite solar cells

Novel donor-acceptor-donor structured small molecular hole transporting materials are developed through a facile route by crosslinking dithienopyrrolobenzothiadiazole and phenothiazine or triarylamine-based donor units. The strong push/pull electron capability of dithienopyrrolobenzothiadiazole/ phenothiazine and large π-conjugated dithienopyrrolobenzothiadiazole facilitate hole mobility and high conductivity. The devices using the dithienopyrrolobenzothiadiazole/phenothiazine-based hole trans-porting material achieved a power conversion efficiency of 14.2% under 1 sun illumination and improved stability under 20% relative humidity at room temperature without encapsulation. The present finding highlights the potential of dithienopyrrolobenzothiadiazole-based donor-acceptor-donor small molecular hole transporting materials for perovskite solar cells.

Single photon emitters originating from donor-acceptor pairs

Starting from the groundbreaking work in graphene[1],the active research in two-dimensional(2D)layered materials has unveiled a number of exotic phenomena that are unique in the 2D limit.In addition to the semimetal graphene,the semiconducting transition metal dichalcogenides(TMDs)and the insulating hexagonal boron nitride(hBN)are also the main driving forces of the field.

Metal-oxoacid-mediated oxyhydroxide with proton acceptor to break adsorption energy scaling relation for efficient oxygen evolution

Metal oxyhydroxides(MOOH)generated from irreversible reconstructions of transition metal compounds are intrinsic active species for oxygen evolution reaction,whose activities are still constrained by sluggish deprotonation kinetics and inherent adsorption energy scaling relations.Herein,we construct a tunable proton acceptor(TPA)on oxyhydroxides by in-situ reconstruction of metal oxoacids such as NiC2O4to accelerate deprotonation and break adsorption energy scaling relations during OER.The modified C_(2)O_(4)^(2-)as a TPA can easily extract H of*OH(forming*HC2O4intermediate)and then promote deprotonation by the transmitted hydrogen bond with*OOH along conjugated(H...)O=C-O(-H)chain.As a result,Ni OOH-C2O4shows non-concerted proton-electron transfer and improved deprotonation rate,and delivers a good OER activity(270 mV@10 mA cm-2).The conjugate acidity coefficient(pKa)of the modified oxoacid group can be a descriptor for TPA selection.This TPA strategy can be universally applied to Co-,Fe-,and Ni-based oxyhydroxides to facilitate OER efficiency.

Synthesis and Cation-Mediated Electron Transfer in Fluorescence Quenching of Donor-Acceptor Podands

Reduced rate constants of photoinduced electron transfer in intramolecular fluorescence quenching of donor-acceptor podands induced by cation-complexation are observed in the highly exothermic reactions.

Donor‐acceptor carbon nitride with electron‐withdrawing chlorine group to promote exciton dissociation

Carbon nitride(C_(3)N_(4))is promising for photocatalytic hydrogen production,but photogenerated electrons and holes in C_(3)N_(4)usually tend to exist as excitons due to intrinsic Coulomb interactions making its photocatalytic activity unsatisfactory.Herein,a well‐designed intramolecular C_(3)N_(4)‐based donor‐acceptor(D‐A)photocatalytic system was constructed to promote exciton dissociation.Due to its good chemical compatibility with melamine and appropriate sublimation property,2‐amino‐4,6‐dichloropyrimidine unit was chosen as the monomer to react with melamine to construct intramolecular D‐A system(CNCl_(x)).The hydrogen evolution rate of CNCl_(0.15)is 15.3 times higher than that of bulk C_(3)N_(4)under visible light irradiation,with apparent quantum efficiency of 13.6%at 420 nm.The enhanced activity is attributed to introduced electron‐withdrawing−Cl group as terminal group in the resulted CNCl_(x) samples,which can build internal electric field to promote the exciton dissociation into free electron and hole.In addition,lower work function value of CNCl_(x) samples indicates that internal electric field can help free electrons and holes transfer to the surface of CNCl_(x) samples for photocatalytic reaction.

DFT and TD-DFT Calculations of Orbital Energies and Photovoltaic Properties of Small Molecule Donor and Acceptor Materials Used in Organic Solar Cells

DFT and TD-DFT calculations of HOMO and LUMO energies and photovoltaic properties are carried out on four selected pentathiophene donor and one IDIC-4F acceptor molecules using B3LYP and PBE0 functionals for the ground state energy calculations and CAM-B3LYP functional for the excited state calculations.The discrepancy between the calculated and experimental energies is reduced by correlating them with a linear fit.The fitted energies of HOMO and LUMO are used to calculate the Voc of an OSC based on these donors and acceptor blend and compared with experimental values.Using the Scharber model the calculated PCE of the donor-acceptor molecules agree with the experiment.It has been found that fluorine substitution can be used to improve charge transport by reducing the electron and hole reorganization energies of the molecules.It is also found that the introduction of fluorine onto the donor pentathiophene unit of the donor molecule results in a change of polarity of the distributed charges in the molecule due to the high electronegativity of the fluorine atom.The quantum chemical potential(μ),chemical hardness(η)and electronegativity(χ),and electrostatic potential maps(EPMs)are also calculated to identify different charge distribution regions in all five molecules.

High Responsivity Organic Ultraviolet Photodetector Based on NPB Donor and C60 Acceptor

We report fabrication and characterization of organic heterojunction UV detectors based on N,N＇-bis（naphthalen- 1-y1）-N,N＇-bis （phenyl） benzidine （NPB） and fullerene C60. The effects of different thicknesses of NPB and C60 layers are studied and compared. Notably, the optimal thicknesses of electron acceptor C60 and electron donor NPB are 40 nm and 80 nm, respectively. The J V characteristic curves of the device demonstrate a three-order- of-magnitude difference when illuminated under a 350nm UV light and in the dark at -0.5 V. The device exhibits high sensitivity in the region of 320-380nm with the peak located around 35Onm. Especially, it shows excellent photo-response characteristic with a responsivity as high as 315 mA/W under the illumination of 192μW.cm 2 350nm UV light at -5 V. These results indicate that the NPB/C60 heterojunction structure device might be used as low-cost low-voltage UV photodetectors.

Lithium Salt of NH_2-substituted Graphene Nanoribbon with Twofold Donor-acceptor Framework: Large Nonlinear Optical Property

Based on graphene, a new class of second-order nonlinear optical（NLO） material, the lithium salt of NH2-substituted graphene nanoribbon with the twofold donor（D）/acceptor（A） mode, was reported. Eight stable 2Li-2NH2-GNR lithium salts, especially cis lithium salts, display considerably large β0 values. The combination of NH2-substituting and cis Li-doping makes β0 greatly increased from 0（GNR） to 1.2×105―2.9×105 a.u.（cis-2Li- 2NH2-GNRs）. Our largest β0 value（2.9×105 a.u.） for cis-2Li-1,3-2NH2-AGNR is comparable to the record value of 1.7×105 a.u. for a long donor-acceptor polyene.

Phenomenon of Mutual Compensation of Radiation Donors and Acceptors and Creation of Radiation-Resistant Materials

The phenomenon of mutual compensation of radiation donors and acceptors is discovered in IrtAs-InP solid solutions. This phenomenon is a result of opposite directed radiation processes, taking place in the irradiated InAs-InP solid solutions. The radiation creates donor type defects in the sublattice of InAs and electrons concentration increases. The contrary process occurs in the sublattice of InP. Radiation originates acceptor type defects and the carrier concentration decreases. The noted effect is going on in the all alloy composition. Exact mutual compensation of radiation donors and acceptors is achieved by selecting of the alloys definite composition. As a result, the main parameter of semiconductors-electrons concentration remains constant even under the hard radiation with fluences of Ф = 2 × 10^18 fast neutrons/cm^2. So there has been created radiation-resistant material.

Theoretical Studies on the First Hyperpolarizabilities of One-dimensional Donor-bridge-acceptor Chromophores

The ground-state dipole moments and second-order nonlinear optical （NLO） properties of a series of one-dimensional （1D） chromophores with donor-bridge-acceptor （D-B-A） structures have been investigated by using the second-order MФller-Plesset （MP2） and density functional theory （DFT） methods with the basis set of 6-31＋G（d）. According to the calculated results, the relationship between the molecular static first hyperpolarizability （βμ） and the directions of electron transition has been summarized. In terms of the sign of βμ, these 1D organic chromophores were classified into two categories： type Ⅰ with negative βμ and type Ⅱ bearing positive βμ. The analyses show that the remarkable difference of the first hyperpolarizabilities between Ⅰ and Ⅱ chromophores is associated mainly with the electrostatic interaction between terminal groups and the transport electrons in excited states. Moreover, different from the popular viewpoint, the obtained results also show that most of this series of 1D D-B-A molecules are more charge-separated in the ground states than in the excited states. As a whole, this theoretical investigation, to some extent, can be considered as a useful reference in designing the NLO chromophores with large first hyperpolarizabilities.

Theoretical Studies on the First Hyperpolarizabilities of One-dimensional Donor-bridge-acceptor Chromophores and New Applications of BLA in Determining Molecular First Hyperpolarizabilities

We present a quantum-chemical analysis of the relationship between the bond length alteration （BLA） and the static first hyperpolarizability of a series of one-dimensional （1D） chromophores with donor-bridge-acceptor （D-B-A） structures. The calculated results show that the parameter BLA can be considered as an indicator to evaluate the molecular first hyper- polarizability. Along the direction of molecular ground-state dipole moments, the evolutions of BLA can be classified into three categories： the first is a non-monotonic line, which represents most chromophores; the second is monotonic increasing; and the third, contrarily, is monotonic decreasing. On the whole, the first hyperpolarizabilities of these studied chromophores are the monotonic functions of BLA along the direction of dipole moments. Therefore, the first hyperpolarizability of these 1D chromophores can be preliminarily evaluated in terms of the development of BLA without a rigorous computation. In other words, one can roughly estimate the relative magnitude of the first hyperpolarizability according to the optimized geometry.

Theoretical DFT(B3LYP)/6-31+G(d) study on the prediction of the preferred interaction site of 3-methyl-4-pyrimidone with different proton donors

Theoretical calculations were carried out using the DFT/B3LYP/6-31+G(d) methodology in an attempt to predict the preferred interaction site of a polyfunctional heterocyclic base 3-methyl-4- pyrimidone molecule with a series of proton donors of different acidic strength, i.e. water, methanol, phenol, 1-naphtol, 2,4,5 trichlorophenol, pentachlorophenol, picric acid and hydrogen chlordide. Computed H-bond interaction energies (ΔEc), internuclear and intermolecular distances r(O…H) and r(O…O), infrared frequency shifts Δv(C=O) and (Δv(OH) are proved to be reliable parameters for predicting the preferred interaction site of 3-methyl-4-pyrimidone. These computational data suggest that the O-H…O=C complex is preferred with water, methanol, phenol, 1-naphtol, 2,4,5 trichlorophenol and pentachlorophenol. However, for H-bonding with stronger acids such as picric acid or hydrochloric acid, the computational data suggest that the H-bonding occurs at the N1 ring atom of 3-methyl-4-pyrimidone. In the O-H…O=C com- plex, where the H-bond at the carbonyl O-atom can be oriented “anti” (Ha) and “syn” (Hb) with respect to the N3 atom, the same computational data suggest a higher stability of the “anti-O” compared to the “syn-O” orientation.

Tackling the proton limit under industrial electrochemical CO_(2)reduction by a local proton shuttle

Industrial CO_(2)electroreduction has received tremendous attentions for resolution of the current energy and environmental crisis,but its performance is greatly limited by mass transport at high current density.In this work,an ion‐polymer‐modified gas‐diffusion electrode is used to tackle this proton limit.It is found that gas diffusion electrode‐Nafion shows an impressive performance of 75.2%Faradaic efficiency in multicarbon products at an industrial current density of 1.16 A/cm^(2).Significantly,in‐depth electrochemical characterizations combined with in situ Raman have been used to determine the full workflow of protons,and it is found that HCO_(3)^(−)acts as a proton pool near the reaction environment,and HCO_(3)^(−)and H_(3)O^(+)are local proton donors that interact with the proton shuttle−SO_(3)^(−)from Nafion.With rich proton hopping sites that decrease the activation energy,a“Grotthuss”mechanism for proton transport in the above system has been identified rather than the“Vehicle”mechanism with a higher energy barrier.Therefore,this work could be very useful in terms of the achievement of industrial CO_(2)reduction fundamentally and practically.

Phase engineering of a donor-doped air electrode for reversible protonic ceramic electrochemical cells

Reversible protonic ceramic electrochemical cells(R-PCECs)demonstrate great feasibility for efficient energy storage and conversion.One critical challenge for the development of R-PCECs is the design of novel air electrodes with the characteristics of high catalytic activity and acceptable durability.Here,we report a donor doping of Hf into the B-site of a cobalt-based double perovskite with a nominal formula of PrBa_(0.8)Ca_(0.2)Co_(1.9)Hf_(0.1)O_(5tδ)(PBCCHf_(0.1)),which is naturally reconfigured to a double perovskite PrBa_(0.8-x)Ca_(0.2)Co_(1.9)Hf_(0.1)-xO5tδ(PBCCHf_(0.1)-x)backbone and nano-sized BaHfO3(BHO)on the surface of PBCCHf_(0.1)x.The air electrode demonstrates enhanced catalytic activity and durability(a stable polarization resistance of 0.269Ωcm2 for~100 h at 600℃),due likely to the fast surface exchange process and bulk diffusion process.When employed as an air electrode of R-PCECs,a cell with PBCCHf_(0.1) air electrode demonstrates encouraging performances in modes of the fuel cell(FC)and electrolysis(EL)at 600℃:a peak power density of 0.998 W cm^(-2)and a current density of1.613 A cm^(-2)at 1.3 V(with acceptable Faradaic efficiencies).More importantly,the single-cell with PBCCHf_(0.1) air electrode demonstrates good cycling stability,switching back and forth from FC mode to EL mode0.5 A cm^(-2)for 200 h and 50 cycles.

基于喹喔啉和吡啶并吡嗪及咔唑和二苯胺衍生物电子给体-受体结构荧光材料的合成和光电性能

通过α-二酮与邻苯二胺、吡啶二胺缩合反应,构建了喹喔啉和吡啶并吡嗪衍生物作为电子受体,分别以二苯胺、咔唑衍生物为电子给体,合成了4个具有电子给体-电子受体结构的氮杂环荧光材料F1~F4。通过低温荧光/磷光光谱、荧光寿命测试,结合密度泛函理论计算可知,F1~F4均为荧光小分子。室温荧光光谱结果表明,利用电子给体和受体的电子效应不同可以调控材料的发光颜色,其中三苯胺相对于苯基咔唑的供电子能力更强,表现为F1比F2、F3比F4红移现象更加明显;而吡啶并吡嗪具有多氮的缺电子结构,与喹喔啉相比共轭程度增加,导致F3比F1、F4比F2发生的斯托克斯位移数值增大。总之,F1~F4的甲苯溶液最大荧光光谱发射峰位于529、464、568和507 nm,荧光寿命分别为12.21、2.61、9.76和6.03 ns,荧光量子效率最高可达98.2%,具有良好的发光性能。将F1~F4发光材料掺杂在主体材料中制备了有机电致发光二极管DF1~DF4。所得器件DF1和DF3性能更好,最大电流效率分别为13.38和11.98 cd·A-1,且最大外量子效率分别达到4.8%和4.5%。

新型供体-受体g-C_(3)N_(4)有机半导体光催化铀分离技术

从核废水中光催化提取铀是避免环境破坏和回收铀资源的一种可行方法,但设计具有快速迁移光生电荷和表面反应动力学的高效光催化剂用于去除含铀废水中的U(Ⅵ)仍然是一个重大挑战。采用无模板的自组装技术,成功构建了空心管状g-C_(3)N_(4)(TCN),并通过将间苯二酚引入TCN的骨架结构中,制备了管状供体-受体(D-A)有机半导体光催化剂B-TCN_(x),用于空气气氛下光催化去除U(Ⅵ)。分子内D-A体系的构建,使得电子和空穴分别聚集在受体和供体部分,这降低了电子-空穴对的复合。此外,电子和空穴在受体和供体部分的积累导致了内置电场的形成,从而促进了载流子的迁移。结果表明,B-TCN_(60)在120 min内对U(Ⅵ)的去除率达到96.8%,其动力学常数(0.031 14 min^(-1))是TCN (0.012 15 min^(-1))的2.58倍。并且在连续5次循环后变化不大,具有稳定性和可重复性。因此,D-A光催化剂具有很高的光催化铀分离效率。这项研究为深入了解光催化铀分离提供了启示和指导。

调控共价有机框架供-受体促进光催化水析氧

为探究电子供体-受体结构对共价有机框架(COFs)材料光催化性能的影响,以N,N'-对乙腈苯基-1,4,5,8-萘二酰亚胺(NBA)为基础构筑单体,分别与供电子的三(4-甲酰基)苯胺(N-CHO)、吸电子的1,3,5-三(4-甲酰苯基)三嗪(TFPT)脱水缩合,构筑了由C=C连接的NN-COF和NT-COF。采用XRD、FTIR、^(13)CNMR、XPS、SEM、TEM、EDS和紫外光电子能谱(UPS)表征了两种COFs材料的结构、形貌和光电性能,并测试其光催化水分子氧化反应(OER)性能。结果表明,与NN-COF相比,NT-COF中三嗪单元的吸电子能力和高度平面性使其具有更紧密的层间π-π堆积、更宽的可见光吸收范围和更强的光生载流子产生能力;Co(NO_(3))_(2)·6H_(2)O作为助催化剂添加后,NN-COF和NT-COF在连续6 h内平均析氧速率分别为303.73和449.53μmol/(g·h);NT-COF中相对缺电子的萘酰亚胺单元更有利于光生空穴在其杂原子上的积累,从而更高效地催化水分子OER的进行。

全小分子有机太阳能电池研究进展

近年来,非富勒烯小分子受体材料(SMAs)由于具有高吸收系数、能级和带隙可调、优异的电学性质和光伏性能等优点受到广泛关注,设计和合成高性能SMAs已成为有机太阳能电池(OSCs)的研究热点。得益于SMAs的快速发展,OSCs的能量转换效率在几年内从3%~4%提高到19%。在成功合成小分子受体材料ITIC和Y6基础上,研究人员对分子结构设计进行了深入研究,开发出许多性能优异的SMAs。这些SMAs在提高器件效率和太阳能电池性能方面发挥了至关重要的作用。综述了全小分子OSCs的研究进展,并展望了未来OSCs的发展方向。