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N-doping offering higher photodegradation performance of dissolved black carbon for organic pollutants: experimental and theoretical studies

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第4期25卷 340-356页

作者： Yong GUO Mengxia CHEN Ting CHEN Ying GUO Zixuan XU Guowei XU Soukthakhane SINSONESACK Keophoungeun KANMANY Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes Ministry of EducationCollege of EnvironmentHohai UniversityNanjing 210093China Key Laboratory of Environmental Engineering of Jiangsu Province Jiangsu Provincial Academy of Environmental ScienceNanjing 210036China State Key Laboratory of Pollution Control and Resource Reuse Nanjing UniversityNanjing 210023China Central Environmental Laboratory Natural Resources and Environment Research InstituteMinistry of Natural Resources and EnvironmentVientiane 999012Laos

We investigated the influence mechanism of N-doping for dissolved black carbon(DBC)photodegradation of organic pollutants.The degradation performance of N-doped dissolved black carbon(NDBC)for tetracycline(TC)(71%)is better than that for methylene blue(MB)(28%)under irradiation.These levels are both better than DBC degradation performances for TC(68%)and MB(18%)under irradiation.Reactive species quenching experiments suggest that h and-O,are the main reactive species for NDBC photodegraded TC,while-OH and h*are the main reactive species for NDBC photodegraded MB.-OH is not observed during DBC photodegradation of MB.This is likely because N-doping increases valence-band(VB)energy from 1.55 eV in DBC to 2.04 eV in NDBC;the latter is strong enough to oxidize water to form-OH.Additionally,N-doping increases the DBC band gap of 2.29 to 2.62 eV in NDBC,resulting in a higher separation efficiency of photo-generated electrons-holes in NDBC than in DBC.AIl these factors give NDBC stronger photodegradation performance for TC and MB than DBC.High-performance liquid chromatography-mass spectrometry(HPLC-MS)characterization and toxicity evaluation with the quantitative structure-activity relationship(QSAR)method suggest that TC photodegradation intermediates produced by NDBC have less aromatic structure and are less toxic than those produced by DBC.We adopted a theoretical approach to clarify the relationship between the surface groups of NDBC and the photoactive species produced.Our results add to the understanding of the photochemical behavior of NDBC.

关键词： Dissolved black carbon(DBC) N-doping Organic pollutants band gap Photodegradation

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Inhibiting the bipolar effect via band gap engineering to improve the thermoelectric performance in n-type Bi_(2-x)Sb_(x)Te_(3)for solid-state refrigeration

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Journal of Materials Science & Technology 2023年第7期138卷 50-58页

作者： Dongliang Su Jiahui Cheng Shan Li Shengnan Zhang Tu Lyu Chaohua Zhang Junqin Li Fusheng Liu Lipeng Hu College of Materials Science and Engineering Shenzhen Key Laboratory of Special Functional MaterialsGuangdong Research Center for Interfacial Engineering of Functional MaterialsGuangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and UtilizationInstitute of Deep Earth Sciences and Green EnergyShenzhen UniversityShenzhen 518060China Superconducting Materials Research Center Northwest Institute for Nonferrous Metal ResearchXi’an 710016China

To date,the benchmark Bi_(2)Te_(3)-based alloys are still the only commercial material system used for ther-moelectric solid-state refrigeration.Nonetheless,the conspicuous performance imbalance between the p-type Bi_(2-x)Sb_(x)Te_(3)and n-type Bi_(2)Te_(3-x)Se_(x) legs has become a major obstacle for the improvement of cooling devices to achieve higher efficiency.In our previous study,novel n-type Bi_(2-x)Sb_(x)Te_(3)alloy has been pro-posed via manipulating donor-like effect as an alternative to mainstream n-type Bi_(2)Te_(3-x)Se_(x).However,the narrow bandgap of Bi_(2-x)Sb_(x)Te_(3)provoked severe bipolar effect that constrained the further improvement of zT near room temperature.Herein,we have implemented band gap engineering in n-type Bi_(1.5)Sb_(0.5)Te_(3)by employing isovalent Se substitution to inhibit the undesired intrinsic excitation and achieve the dis-tinguished room-temperature zT.First,the preferential occupancy of Se at Te^(2)site appropriately enlarges the band gap,thereby concurrently improving the Seebeck coefficient and depressing the bipolar thermal conductivity.In addition,the Se alloying mildly suppresses the compensation mechanism and essentially preserves the already optimized carrier concentration,which maintains the peak zT near room tempera-ture.Moreover,the large strain field and mass fluctuation generated by Se alloying leads to the remark-able reduction of lattice thermal conductivity.Accordingly,the zT value of Bi_(1.5)Sb_(0.5)Te_(2.8)Se_(0.2)reaches 1.0 at 300 K and peaks 1.1 at 360 K,which surpasses that of most well-known room-temperature n-type thermoelectric materials.These results pave the way for n-type Bi_(2-x)Sb_(x)Te_(3)alloys to become a new and promising top candidate for large-scale solid-state cooling applications.

关键词： Thermoelectric Bi_(2)Te_(3) band gap Bipolar effect Point defects

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Tunable phase transition, band gap and SHG properties by halogen replacement of hybrid perovskites [(thiomorpholinium)PbX_(3), X = Cl,Br,I]

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Chinese Chemical Letters 2022年第2期33卷 1032-1036页

作者： Simin Liu Lei He Yuzhen Wang Pingping Shi Qiong Ye Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics and School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189China

By the replacement of halogen anion,three new multifunctional organic-inorganic hybrid perovskites(thiomorpholinium)PbX_(3)(X=Cl,Br,I)were successfully synthesized and underwent reversible struc-tural transformation above room temperature,accompanied by the anomalous change of dielectric con-stant.With the adjustment of the halogen anion from Cl to I in the inorganic skeleton,the space group is transformed from centrosymmetric space group P2_(1)/c((thiomorpholinium)PbCl_(3))to chiral one P2_(1)2_(1)2_(1)((thiomorpholinium)PbBr3,(thiomorpholinium)PbI_(3))at room temperature.The ordered-disordered tran-sition of organic cations and the change of hydrogen bonds with the increase of temperature lead to above-room-temperature phase transitions.Ultraviolet absorption and second-harmonic generation(SHG)measurements confirmed that both the band gap and SHG activity of(thiomorpholinium)PbX_(3)(X=Cl,Br,I)crystals were tunable.The band gaps reveal a broadening trend with 3.532 e V,3.410 e V and 3.175 e V along the Cl→Br→I series.This work provides an effective molecular design for multifunctional organic-inorganic perovskites.

关键词： Phase transition band gap Nonlinear optical Organic-inorganic hybrid perovskite Halogen replacement

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band gap tuning and p to n-type transition in Mn-doped CuO nanostructured thin films

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Journal of Semiconductors 2022年第1期43卷 59-68页

作者： R.Rahaman M.Sharmin J.Podder Department of Physics Bangladesh University of Engineering and TechnologyDhaka 1000Bangladesh

Here we discuss the synthesis of copper(II)oxide(CuO)and manganese(Mn)-doped CuO thin films varying with 0 to 8 at%Mn using the spray pyrolysis technique.As-deposited film surfaces comprised of agglomerated spherical nanoparticles and a semi-spongy porous structure for 4 at%Mn doping.Energy dispersive analysis of X-rays confirmed the chemical composi-tion of the films.X-ray diffraction spectra showed a polycrystalline monoclinic structure with the predominance of the(11)peak.Optical band gap energy for direct and indirect transitions was estimated in the ranges from 2.67-2.90 eV and 0.11-1.73 eV,respectively.Refractive index and static dielectric constants were computed from the optical spectra.Electrical resistivity of CuO and Mn-doped CuO(Mn:CuO)thin films was found in the range from 10.5 to 28.6Ω·cm.The tiniest electron effective mass was calculated for 4 at%Mn:CuO thin films.P to n-type transition was observed for 4 at%Mn doping in CuO films.Carrier con-centration and mobility were found in the orders of 10^(17)cm^(-3)and 10^(-1)cm^(2)/(V·s),respectively.The Hall coefficient was found to be between 9.9 and 29.8 cm^(3)/C.The above results suggest the suitability of Mn:CuO thin films in optoelectronic applications.

关键词： Mn:CuO spray pyrolysis FESEM XRD band gap Hall effect

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band gap calculation and photo catalytic activity of rare earths doped rutile TiO_2

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Journal of Rare Earths 2009年第3期27卷 461-468页

作者：边亮宋绵新周天亮赵效勇戴清清 Key Laboratory for Advanced Building Materials of Sichuan Province South West University of Science and Technology University of Science and Technology Beijing Shanghai East Sea Marine Engineering Survey and Design Institute

The density of states （DOS） of 17 kinds of rare earths （RE） doped rutile TiO2 was by using first-principles density functional theory （DFT） calculation. The band gap widths of RE doped futile TiO2 were important factors for altering their absorbing wavelengths. The results show that RE ions could obviously reduce the band gap widths and form of energy of ruffle TiO2 except Lu, Y, Yb and Sc, and the order of absorbing wavelengths of RE doped ruffle TiO2 were the same as that of the results of calculation. The ratio of RE dopant was another important factor for the photo catalytic ＇activity of RE doped rutile TiO2, and there was an optimal ratio of dopant. There was a constant for predigesting the calculation difficulty, respectively, which were 0.5mol.% and 100 mol^-1 under supposition. The band gap widths of RE doped rutile TiOz by DFT calculation were much larger than that by experiment. Finally, by transferring the calculation values to experiment values, it could be found and predicted that RE enlarged obviously the absorbing wavelengh of ruffle TiO2. In addition, the degree of RE ions edging out the Ti atom using the parameters of RE dements was computed.

关键词： density functional theory ruffle TiO2 band gap rare earths

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band gap of Strained Graphene Nanoribbons

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Nano Research 2010年第3期3卷 189-199页

作者： Yang Lu Jing Guo Department of Electrical and Computer Engineering University of FloridaGainesvilleFL 32611USA

The band structures of strained graphene nanoribbons(GNRs)are examined using a tight-binding Hamiltonian that is directly related to the type and magnitude of strain.Compared to a two-dimensional graphene whose band gap remains close to zero even if a large strain is applied,the band gap of a graphene nanoribbon(GNR)is sensitive to both uniaxial and shear strains.The effect of strain on the electronic structure of a GNR depends strongly on its edge shape and structural indices.For an armchair GNR,a weak uniaxial strain changes the band gap in a linear fashion,whereas a large strain results in periodic oscillation of the band gap.On the other hand,shear strain always tends to reduce the band gap.For a zigzag GNR,the effect of strain is to change the spin polarization at the edges of GNR,and thereby modulate the band gap.A simple analytical model,which agrees with the numerical results,is proposed to interpret the response of the band gap to strain in armchair GNRs.

关键词： Graphene nanoribbons(GNRs) band gap strain

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band gap narrowing of TiO_2 by compensated codoping for enhanced photocatalytic activity

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Journal of Natural Gas Chemistry 2012年第3期21卷 302-307页

作者： Jindou Huang Shuhao Wen Jianyong Liu Guozhong He State Key Laboratory of Molecular Reaction Dynamics Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChinaa Graduate University of Chinese Academy of Sciences Beijing 100049Chin

In this study, we have performed first-principles screened exchanged hybrid density function theory with the HSE06 function calculations of the C-Mo, C-W, N-Nb and N-Ta codoped anatase TiO2 systems to investigate the effect of codoping on the electronic structure of TiO2. The calculated results demonstrate that （W（s）＋C（s）） codoped TiO2 narrows the band gap significantly, and have little influence on the position of conduction band edges, therefore, enhances the efficiency of the photocatalytic hydrogen generation from water and the photodegradation of organic pollutants. Moreover, the proper oxygen pressure and temperature are two key factors during synthesis which should be carefully under control so that the desired （W（s）＋C（s）） codoped TiO2 can be obtained.

关键词： hybrid DFT TiO2 codoping thermodynamic stability band gap photocatalysts

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Temperature dependence of biaxial strain and its influence on phonon and band gap of GaN thin film

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Chinese Physics B 2008年第6期17卷 2245-2250页

作者：徐宏妍菅傲群薛晨阳陈阳张斌珍张文栋张志国冯震 Key Laboratory of Instrumentation Science & Dynamic Measurement (North University of China) Ministry of Education National Key Laboratory for Electronic Measurement Technology North University of China The 13th research institute of CETC

Hexagonal GaN epilayer grown on sapphire substrate by metal organic chemical vapour deposition （MOCVD） is studied using Raman scattering and photoluminescence in a temperature range from 100K to 873 K. The model of strain （stress） induced by the different lattice parameters and thermal coefficients of epilayer and substrate as a function of temperature is set up. The frequency and the linewidth of E2^high mode in a GaN layer are modelled by a theory with considering the thermal expansion of the lattice, a symmetric decay of the optical phonons, and the strain （stress） in the layer. The temperature-dependent energy shift of free exeiton A is determined by using Varshni empirical relation, and the effect of strain （stress） is also investigated. We find that the strain in the film leads to a decreasing shift of the phonon frequency and an about 10meV-inereasing shift of the energy in a temperature range from 100 K to 823 K.

关键词： biaxial strain phonon band gap GaN

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Surface rumples and band gap reductions of cubic BaZrO_3 (001) surface studied by means of first-principles calculations

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Chinese Physics B 2008年第1期17卷 274-280页

作者：张超王春雷李吉超杨鲲张艳飞吴清早 School of Physics and Microelectronics State Key Laboratory of Crystal MaterialsShandong University

Electronic properties of the （001） surface of cubic BaZrO3 with BaO and ZrO2 terminations have been studied using first-principles calculations. Surface structure, partial density of states, band structure and surface energy have been obtained. We find that the largest relaxation appears in the first layer of atoms, and the relaxation of the BaO-terminated surface is larger than that of the ZrO2-terminated surface. The surface rumpling of the BaO-terminated surface is also larger than that of the ZrO2-terminated surface. Results of surface energy calculations reveal that the BaZrO3 surface is likely to be more stable than the PbZrO3 surface.

关键词： surface band gap BaZrO3 first-principles

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band gap properties of 2D square lattice photonic crystal composed of rectangular cells

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Frontiers of Optoelectronics 2013年第3期6卷 346-352页

作者： Somaye SERAJMOHAMMADI Hamed ALIPOUR-BANAEI Department of Electrical Engineering Ahar Branch Islamic Azad University Ahar lran Department of Electronics Tabriz Branch Islamic Azad University Tabriz lran

In this paper, the photonic band gap （PBG） properties of two dimensional （2D） square lattice photonic crystal structures composed of rectangular cells were studied. The effect of refractive index, rectangles length and the ratio of width to length of the rectangles on the PBG properties of the structure with different configura- tions was investigated. It is found that the density of gaps in both modes （transverse electric （TE） and transverse magnetic （TM）） is high for structure composed of rectangular dielectric rods in gaps is very low for structure pores in dielectric material. air, while the density of the composed of rectangular air

关键词： photonic crystal （PhC） band gap refractive index

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