实现照明 LED 用 p-ZnO 中 Ag-2N高共掺粒子数分数机理

基于密度泛函理论的第一性原理方法,对六方纤锌矿结构的Zn O晶体,N、Ag分别掺杂Zn O,以及Ag-2N共掺杂Zn O晶体的几何结构分别进行了比较研究,在此基础上计算得到了未掺杂Zn O晶体和不同掺杂情况下Zn O晶体的能带结构、总体态密度、分波态密度和电荷布居数.结果显示:Ag-2N共掺杂Zn O具有较稳定的结构,能有效提高载流子粒子数分数,更容易得到稳定的p型Zn O.     

两步法制备B-Mo共掺杂BiVO4及光催化活性研究

采用柠檬酸络合和浸渍两步法制备了一系列B-xMo共掺杂BiVO_4可见光光催化剂,并采用XRD、XPS、SEM、EDS、BET和UV-vis等表征和分析。以降解甲基橙(MO)、亚甲基蓝(MB)、金橙Ⅱ号(AOⅡ)和罗丹明B(RhB)溶液为指针反应,考察掺杂对BiVO_4可见光催化活性的影响。结果表明:B-Mo共掺杂能抑制BiVO_4晶粒生长,比表面积增大,共掺杂后BiVO_4禁带宽度窄化,且氧空位较单掺杂增加。当Mo掺杂量为2.5%(原子分数)时制备的B-2.5Mo-BiVO_4对甲基橙的降解率达96%左右,且该样品也能有效降解亚甲基蓝(MB)、金橙Ⅱ号(AOⅡ)和罗丹明B(RhB)溶液。     

P-type ZnO thin films prepared by in situ oxidation of DC sputtered Zn3N2:Ga

The feasibility of a new fabrication route for N and Ga codoped p-type ZnO thin films on glass substrates, consisting of DC sputtering deposition of Zn3N2:Ga precursors followed by in situ oxidation in high purity oxygen, has been studied. The effects of oxidation temperature on the structural, optical and electrical properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical transmittance and Hall effect measurements. The results were compared to a control film without Ga. XRD analyses revealed that the Zn3N2 films entirely transformed into ZnO films after annealing Zn3N2 films in oxygen over 500 ℃ for 2 h. Hall effect measurements confirmed p-type conduction in N and Ga codoped ZnO films with a low resistivity of 19.8 Ω·cm, a high hole concentration of 4.6 × 1018 cm-3 and a Hall mobility of 0.7 cm2/(V·s). These results demonstrate a promising approach to fabricate low resistivity p-type ZnO with high hole concentration.     

Modulating Blue Phosphorene by Synergetic Codoping: Indirect to Direct Gap Transition and Strong Bandgap Bowing

The structural and electronic properties of synergistically modified blue phosphorene (BP) is investigated. The inversion and threefold rotational symmetries of BP are broken. The codoping of group IV and VI impurities can turn monolayer BP into direct bandgap semiconductors. The underlying physical mechanism is that group IV and VI impurities tailor the valence band maximum and conduction band minimum, respectively, and move them to Γ. All the bandgaps of monolayer, nanoribbons, and quantum dots of BP can be modulated in a wide range, and the strong bandgap bowing is found. In addition, the Coulomb interactions between the screened impurities are revealed. Lower formation energies indicate the fabricating practicability of synergeticly modified BP. Spin–orbit coupling (SOC) can also be tuned by the introduction of impurities.     

Nb、Al共掺杂MoSi2弹性性质的第一性原理计算

通过第一性原理计算研究了Nb、Al共掺杂MoSi2晶体的电子结构、弹性常数和Mullikan布居数。结果表明,Nb、Al共掺杂可大幅提高MoSi2的韧性和导电性,当Nb和Al共掺杂量达到x=0.25时,MoSi2的弹性模量从408.86GPa降低到261.30GPa。MoSi2的电子态密度和Mullikan布居数分析表明,Nb和Al掺入后MoSi2电子态密度发生蓝移,费米能级处的电荷密度增加,体系的导电性能提高。掺杂后Mo-Al、Nb-Si键布居数减小,键长增大,原子间的共价性减弱,而Al-Si键间的共价性增强。晶体中各方向键长和键能的分布趋于对称化,MoSi2晶体韧性增强。     

共掺杂纳米TiO2光催化剂研究进展

在研究纳米TiO2光催化降解有机物机理的基础上,对纳米TiO2催化性能的影响因素、改性方法及掺杂原理等进行了系统的分析。研究分析表明：共掺杂是提高纳米TiO2光催化性能的有效手段。从而为进一步深入研究纳米TiO2光催化剂的制备及其在可见光条件下对难降解有机物的催化降解性能奠定基础。     

钨镍共掺杂V2O5薄膜的光电特性研究

利用溶胶–凝胶旋涂法和后退火工艺在FTO导电玻璃上制备了钨镍共掺杂V₂O₅薄膜,研究了薄膜在不同温度和不同偏压下的光电特性和相变特性。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM） 和X射线光电子能谱仪（XPS） 测试了钨镍共掺杂V₂O₅薄膜的晶体结构、表面形貌和组分,分析了不同钨镍共掺杂浓度对V₂O₅薄膜相变光电特性的影响。结果表明,当钨和镍的掺杂质量分数分别为3 %和1.5 %时,钨镍共掺杂的V₂O₅薄膜的相变温度为218.5 ℃,在可见光范围内有较高的透过率,在近红外1310 nm波长处的光学透过率达48.83%,与未掺杂V₂O₅薄膜的光学透过率相比提高了10.29%,薄膜电阻降低了30.53%,热致回线宽度收窄为15 ℃,说明钨镍共掺杂的V₂O₅薄膜具有良好的可逆相变光电特性,有望在新型光电器件领域得到较好的应用。     

Molecular‐Level Design of Hierarchically Porous Carbons Codoped with Nitrogen and Phosphorus Capable of In Situ Self‐Activation for Sustainable Energy Systems

Hierarchically porous carbons are attracting tremendous attention in sustainable energy systems, such as lithium ion battery (LIB) and fuel cell, due to their excellent transport properties that arise from the high surface area and rich porosity. The state‐of‐the‐art approaches for synthesizing hierarchically porous carbons normally require chemical‐ and/or template‐assisted activation techniques, which is complicate, time consuming, and not feasible for large scale production. Here, a molecular‐level design principle toward large‐scale synthesis of nitrogen and phosphorus codoped hierarchically porous carbon (NPHPC) through an in situ self‐activation process is proposed. The material is fabricated based on the direct pyrolysis of a well‐designed polymer, melamine polyphosphate, which is capable of in situ self‐activation to generate large specific surface area (1479 m² g^?1) and hierarchical pores in the final NPHPC. As an anode material for LIB, NPHPC delivers a high reversible capacity of 1073 mAh g^?1 and an excellent cyclic stability for 300 cycles with negligible capacity decay. The peculiar structural properties and synergistic effect of N and P codopants also enable NPHPC a promising electrocatalyst for oxygen reduction reaction, a key cathodic reaction process of many energy conversion devices (for example, fuel cells and metal air batteries). Electrochemical measurements show NPHPC a comparable electrocatalytic performance to commercial Pt/C catalyst (onset potential of 0.88 V vs reversible hydrogen electrode in alkaline medium) with excellent stability (89.8% retention after 20 000 s continuous operation) and superior methanol tolerance.     

酸催化溶胶-凝胶法Eu2+、Gd3+共掺杂TiO2的制备及光催化活性

采用酸催化溶胶-凝胶法制备了Gd³⁺、Eu²⁺两种稀土金属离子混合掺杂的复合TiO₂光催化剂, 通过TEM、XRD、UV-Vis等分析手段对产物进 行了表征, 结果表明: 样品均呈锐钛矿型结构, 颗粒尺寸的变化只与掺杂离子总量有关, 掺杂量为1.0%时达最小值; 一定比例Eu²⁺、Gd³⁺的混合掺杂, 能增强可见光范围内光响应. 以甲基橙为目标降解物研究了不同比例Eu²⁺、Gd³⁺混合掺杂对纳米二氧化钛光催化活性的影响, Gd³⁺、Eu²⁺适合掺杂量范围分别为0.1%～1.0%和0.5%～1.5%. Eu²⁺、Gd³⁺混和掺入TiO₂光催化剂中产生协同效应, 探讨了Eu²⁺和Gd³⁺与TiO₂之间的相互作用, 讨论了光催化活性与催化剂性质的关系.     

补偿型共掺杂ZnS电子特性的第一性原理计算

基于密度泛函理论的第一性原理平面波赝势方法,对ZnS(Cu,Cl、Br、I)共掺杂体系的晶格结构和电子性质进行了研究。结果表明,相对于单掺杂ZnS体系,补偿型的共掺ZnS体系形成能更低,更有利于提高可见光的催化效率,且由于p-d电子排斥效应使价带向高能方向展宽,而Cu的3p态与非金属原子的杂质态使导带底下移,从而使共掺杂ZnS体系的能带带隙变窄,尤其是CuZnBrS-ZnS带隙值减少了30%,从而延伸吸收边界到可见光区域。且CuZnBrS-ZnS中m*e/m*h相对较大,降低了电子-空穴对重组率,提高了量子效率。最后对补偿型共掺ZnS电子结构进行了讨论。