Atomic Ni directional-substitution on ZnIn_(2)S_(4) nanosheet to achieve the equilibrium of elevated redox capacity and efficient carrier-kinetics performance in photocatalysis

It is a challenge to coordinate carrier-kinetics performance and the redox capacity of photogenerated charges synchronously at the atomic level for boosting photocatalytic activity.Herein,the atomic Ni was introduced into the lattice of hexagonal ZnIn_(2)S_(4) nanosheets(Ni/ZnIn_(2)S_(4))via directionalsubstituting Zn atom with the facile hydrothermal method.The electronic structure calculations indicate that the introduction of Ni atom effectively extracts more electrons and acts as active site for subsequent reduction reaction.Besides the optimized light absorption range,the elevation of Efand ECBendows Ni/ZnIn_(2)S_(4) photocatalyst with the increased electron concentration and the enhanced reduction ability for surface reaction.Moreover,ultrafast transient absorption spectroscopy,as well as a series of electrochemical tests,demonstrates that Ni/ZnIn_(2)S_(4) possesses 2.15 times longer lifetime of the excited charge carriers and an order of magnitude increase for carrier mobility and separation efficiency compared with pristine ZnIn_(2)S_(4).These efficient kinetics performances of charge carriers and enhanced redox capacity synergistically boost photocatalytic activity,in which a 3-times higher conversion efficiency of nitrobenzene reduction was achieved upon Ni/ZnIn_(2)S_(4).Our study not only provides in-depth insights into the effect of atomic directional-substitution on the kinetic behavior of photogenerated charges,but also opens an avenue to the synchronous optimization of redox capacity and carrier-kinetics performance for efficient solar energy conversion.

Recent Progress of Surface Passivation Molecules for Perovskite Solar Cell Applications

Due to the solution processable nature,the prepared perovskite films are polycrystalline with considerable number of defects.These defects,especially defects at interface accelerate the carrier recombination and reduce the carrier collection.Besides,the surface defects also affect the long-term stability of the perovskite solar cells(PVSCs).To solve this problem,surface passivation molecules are introduced at selective interface(the interface between perovskite and carrier selective layer).This review summarizes recent progress of small molecules used in PVSCs.Firstly,different types of defect states in perovskite films are introduced and their effects on device performance are discussed.Subsequently,surface passivation molecules are divided into four categories,and the interaction between the functional groups of the surface passivation molecules and selective defect states in perovskite films are highlighted.Finally,we look into the prospects and challenges in design noble small molecules for PVSCs applications.

Photophysical Properties of Perylenetetracarboxylic Diimide Dimers with Slipped “Face-to-Face” Stacked Structure and Different Bay Substitutions

A series of perylenetetracarboxylic diimides (PDIs) dimers with slipped “face-to-face” stacked structure and different substituents at the bay positions have been synthesized and the molecular structures are characterized by 1H NMR, MALDI-TOF and elemental analysis. And different substituents at the bay positions of the PDI ring bring about various steric hindrances. These different steric hindrances have caused significant differences on the absorption and emission spectra. The correlation between the photophysical properties and the molecular structure is discussed.

Study on the energy level limitations of triplet-triplet annihilation upconversion with anthracene-isomerized dimers as annihilators

The enhancement in the efficiency of triplet-triplet annihilation upconversion(TTA-UC)is mainly determined by the triplet energy transfer(TET)and triplet-triplet annihilation(TTA)between the sensitizers and annihilators.The TET process works efficiently by adjusting the concentration ratio of the sensitizers and annihilators.The efficiency of TTA is determined by the properties of the annihilator.Because TTA is a Dexter-type energy transfer and is affected by the diffusion rate,the energy levels of the excited states and the molecular size are both crucial in TTA.In this study,four isomerized dimers of 9,10-diphenlanthracene(DPA)and anthracene(An)were designed and prepared as annihilators for TTA-UC.The singlet and triplet energy levels could be adjusted by altering the connection position while maintaining the molecular weight and size.When PtOEP was used as the sensitizer,the maximum upconversion efficiency of 9-[4-(9-anthracenyl)phenyl]-10-phenylanthracene(9DPA-9An)was~11.18%.This is four times higher than that of 9,10-diphenyl-2,9-bianthracene(2DPA-9An,2.63%).The calculation of the energies of T_(1)and the higher triplet state(T_(3),because E(T_(2))is similar to the E(T)of these dimers)for these dimers has provided insights into the underlying reasons.These indicated that the energy gap value of 2×E(T_(1))-E(T_(3))is the determining factor for TTA efficiency.This work may provide a better understanding of the excited-state energy levels,which is crucial for designing novel annihilators to enhance the TTA-UCefficiency.

Facile preparation of N-doped corncob-derived carbon nanofiber efficiently encapsulating Fe2O3 nanocrystals towards high ORR electrocatalytic activity

Facile preparation of cost-effective and durable porous carbon-supported non-precious-metal/nitrogen electrocatalysts for oxygen reduction reaction(ORR)is extremely important for promoting the commercialized applications of such catalysts.In this work,the FeCl3-containing porphyrinato iron-based covalent porous polymer(FeCl3·FeP or-CPP)was fabricated in-situ onto porous corncob biomass supports via a simple one-pot method.Subsequent thermal-reduction pyrolysis at 700℃-900℃with CO2 gas as an activating agent resulted in Fe2O3-decorated and N-doped graphitic carbon composite Fe2O3@NC&bio-C with a high degree of graphitization of Fe-involved promotion during pyrolysis(Fe2O3=FeCl3·FePor-CPP derived Fe2O3;NC=N-doped graphene analog;bio-C=the corncob-derived hierarchically porous graphitic biomass carbon framework).The derivedα-Fe2O3 andγ-Fe2O3 nanocrystals(5-10 nm particle diameter)were all immobilized on the N-doped bio-C micro/nanofibers.Notably,the Fe2O3@NC&bio-C obtained at the pyrolysis temperature of 800℃(Fe2O3@NC&bio-C-800),exhibited unusual ORR catalytic efficiency via a 4-electron pathway with the onset and half-wave potentials of 0.96 V and 0.85 V vs.RHE,respectively.In addition,Fe2O3@NC&bio-C-800 also exhibited a high and stable limiting current density of-6.0 mA cm-2,remarkably stability(larger than 91%retention after 10000 s),and good methanol tolerance.The present work represents one of the best results for iron-based biomass material ORR catalysts reported to date.The high ORR activity is attributed to the uniformly distributedα-Fe2O3 andγ-Fe2O3 nanoparticles on the N-enriched carbon matrix with a large specific surface area of 772.6 m^2 g^-1.This facilitates favor faster electron movement and better adsorption of oxygen molecules on the surface of the catalyst.Nevertheless,comparative studies on the structure and ORR catalytic activity of Fe2O3@NC&bioC-800 with Fe2O3@bio-C-800 and NC&bio-C-800 clearly highlight the synergistic effect of the coexisting Fe2O3 nanocrystals,NC,and bio-C on the ORR performance.

High-precision regulation synthesis of Fe-doped Co_(2)P nanorod bundles as efficient electrocatalysts for hydrogen evolution in all-pH range and seawater

The hydrogen evolution reaction(HER)via water electrolysis has gained immense research attention.Seawater electrolysis provides great opportunities for sustainable energy production,but is extremely challenging.Transition metal phosphides are promising candidate electrocatalysts.Herein,we prepared a novel Fe-Co_(2)P bundle of nanorods(BNRs)for catalyzing the HER in seawater electrolysis and over the entire p H range.Cobalt phosphides with different crystal phases and morphologies were obtained by varying the Fe doping amount.The Co:Fe molar ratio of 1:0.5 was found to be optimum.The Fe doping improved the HER performance of Co_(2)P over the entire p H range by providing favorable electronic properties and morphology,lattice distortion,and special coordination environment.The Fe-Co_(2)P BNRs showed higher catalytic activity than 20%Pt/C in seawater at high potentials.The density functional theory calculations revealed that the Fe doping reduced the hydrogen binding strength of Co_(2)P to efficiently accelerate the HER kinetics and produce a favorable charge density.This study provides valuable insights into the design and development of high-efficiency HER catalysts for large-scale seawater electrolysis.

Expanding the dimensionality of proton conduction enables ultrahigh anhydrous proton conductivity of phosphoric acid-doped covalent-organic frameworks

It is of great significance to develop high-temperature anhydrous proton conducting materials.Herein,we report a new strategy to significantly enhance the proton conductivity of covalent organic frameworks(COFs)through expanding the dimensionality of proton conduction.Three COF-based composites,COF-1@PA,COF-2@PA,and COF-3@PA(PA:phosphoric acid),are prepared by PA doping of three COFs with similar pore sizes but different amounts of hydrophilic groups.With the increase of hydrophilic groups,COFs can load more PA because of the enhanced hydrogen–bonding interactions between PA and the frameworks.powder X-ray diffraction(PXRD),scanning electron microscopy(SEM),and two-dimensional(2D)solid-state nuclear magnetic resonance(NMR)analyses show that PA can not only enter the channels of COF-3,but also insert into its 2D interlayers.This expands the proton conduction pathways from one-dimensional(1D)to three-dimensional(3D),which greatly improves the proton conductivity of COF-3.Meanwhile,the confinement effect of 1D channels and 2D layers of COF-3 also makes the hydrogen-bonded networks more orderly in COF-3@PA-30(30μL of PA loaded on COF-3).At 150℃,COF-3@PA-30 exhibits an ultrahigh anhydrous proton conductivity of 1.4 S·cm−1,which is a record of anhydrous proton conductivity reported to date.This work develops a new strategy for increasing the proton conductivity of 2D COF materials.

High Sensitive Ambipolar Response towards Oxidizing NO2 and Reducing NH3 Based on Bis（phthalocyaninato） Europium Semiconductors

High sensitive chemical sensors towards NO2 and NH3 based on the self-assembled nanostructures of the heteroleptic and homoleptic bis（phthalocyaninato） europium complexes with octanaphthoxy phthalocyaninato ligands named Eu（Pc）[Pc（ONh）8] （1） and Eu[Pc（ONh）8]2 （2） [Pc = unsubstituted phthalocyaninate; Pc（ONh）8 = 2,3,9,10,16,17,23,24-octanaphthoxy phthalocyaninate] have been developed. The good conductivity, high crystal- linity and large specific surface area for the self-assemblies of 1 render it excellent sensing property for either electron-accepting gas NO2 in 50--250 ppb range or electron-donating gas NH3 in 2.5--12.5 ppm range due to the optimized molecular packing in the uniform-sized nanopartieles depending on the effective intermolecular interaction between double-decker molecules, among the best results of phthalocyanine-based chemical sensors for detection of NO2 and NH3 at room temperature. Interestingly, self-assemblies of I exhibited n-type response to NO2 and p-type response to NH3, which is the first example of ambipolar charge-transporting gas sensors fabricated from single- component organic semiconductors. However, the self-assemblies of 2 with sixteen bulky naphtboxy groups at the periphery of two Pc rings only present an n-type response to strong oxidant gas NO2 in a relatively high concentration of 0.5 - 1.5 ppm, while are insensitive to weak reducing gas NH3 due to the existence of great steric hindrance from bulky naphthoxy groups and more traps and/or defects in self-assemblies.

基于分子识别功能的铁卟啉/杯八芳烃/石墨烯三元复合材料的制备及其多巴胺电化学传感性能研究

本文用界面自组装法将具有电催化活性的四联苯基铁卟啉(Fe TBPP)和具有特异分子识别功能的对叔丁基杯[8]芳烃(C[8]A)通过自组装法与高导电性的氧化石墨烯(GO)相结合,得到三元Fe TBPP/C[8]A/GO复合膜.对复合膜的结构表征发现,GO的共轭平面和亲水基团分别与Fe TBPP和C[8]A分子有π-π和氢键相互作用,使得两种分子在GO模板上呈现良好的分散性;与这两种分子的单组分膜相比,复合膜具有更加均匀的颗粒形貌和更高的导电性.电化学测试表明,响应电流与多巴胺(DA)浓度呈线性关系,检测范围宽至0.1~1000μM,灵敏度高达17.6μA/mmol,检出限低至25.6 n M.更重要的是,GO对Fe TBPP和C[8]A的锚定和分散使得复合电极对DA的检测具有稳定性、重现性和高选择性,并且该传感器可实现应用于人体尿液和血清样品中DA的高灵敏检测.