Nanoarchitectonics of CdS/ZnSnO3 heterostructures for Z-Scheme mediated directional transfer of photo-generated charges with enhanced photocatalytic performance

The construction of heterostructure is an effective strategy to synergetically couple wide-band-gap with the narrow-band-gap semiconductor with a mediate optical property and charge transfer capability. Herein, the Z-Scheme CdS/ZnSnO₃ (CdS/ZSO) heterostructures were constructed by anchoring CdS nanoparticles on the surface of double-shell hollow cubic ZnSnO₃ via the hydrothermal method. The direct recombination of excited electrons in the conduction band (CB) of ZSO and holes in the valence band (VB) of CdS via d-p conjugation at the interface greatly accelerated the internal electric field (IEF). The transfer mode follows the Z-Scheme mechanism, where CdS/ZSO synergistically facilitates the efficient charges transfer from CdS to ZnSnO₃ through the intimate interface. Here, ZnSnO₃ and CdS serve as an oxidation photocatalyst (OP) and reduction photocatalyst (RP), respectively. Thus, it can promote synergistically the oxidation half-reaction and reduction half-reaction of H₂ evolution. The density-functional theory (DFT) calculation further confirms the charges transfer from CdS to ZnSnO₃. The hydrogen evolution of 5% CdS/ZSO heterostructure reached 1167.3 μmol g^?1, which was about 8 and 3 folds high compared to pristine ZSO (141.9 μmol g^?1) and CdS (315.5 μmol g^?1), during 3 h of reaction respectively. Furthermore, the CdS/ZSO heterostructures could suppress the photo corrosion of CdS, resulting in its high stability. This work is expected to enlighten the rational design of heterostructure for OP and RP to promote the hybrid heterostructures photocatalytic H₂ evolution.     

Single copper sites dispersed on hierarchically porous carbon for improving oxygen reduction reaction towards zinc-air battery

The demand for high-performance non-precious-metal electrocatalysts to replace the noble metal-based catalysts for oxygen reduction reaction(ORR)is intensively increasing.Herein,single-atomic copper sites supported on N-doped three-dimensional hierarchically porous carbon catalyst(Cu₁/NC)was prepared by coordination pyrolysis strategy.Remarkably,the Cu₁/NC-900 catalyst not only exhibits excellent ORR performance with a half-wave potential of 0.894 V(vs.RHE)in alkaline media,outperforming those of commercial Pt/C(0.851 V)and Cu nanoparticles anchored on N-doped porous carbon(CuNPs/NC-900),but also demonstrates high stability and methanol tolerance.Moreover,the Cu₁/NC-900 based Zn-air battery exhibits higher power density,rechargeability and cyclic stability than the one based on Pt/C.Both experimental and theoretical investigations demonstrated that the excellent performance of the as-obtained Cu₁/NC-900 could be attributed to the synergistic effect between copper coordinated by three N atoms active sites and the neighbouring carbon defect,resulting in elevated Cu d-band centers of Cu atoms and facilitating intermediate desorption for ORR process.This study may lead towards the development of highly efficient non-noble metal catalysts for applications in electrochemical energy conversion.     

Morphology/behaviour relationship of nanocomposites based on natural rubber/epoxidized natural rubber blends

In order to analyze the effect of an epoxidized natural rubber (ENR) and filler treatment on the morphology and behavior of natural rubber (NR) nanocomposites, blends of these polymers have been prepared. The nature and extent of the clay dispersions in the filled samples were evaluated by X-ray diffraction. In the presence of ENR, an exfoliated structure was obtained which suggests that enough rubbery polymer was incorporated into the interlayer spacing. The effect of clay in rubber compounds was analyzed through rheological, mechanical and swelling characterization. A sensible improvement in the nanocomposite properties was observed by the addition of organoclay. It has been deduced that the properties of the compounds strongly depend on the extent of the silicate nanolayers dispersion into the rubber matrices as well as on the organoclay type and elastomer compatibility.     

Stepped enhancement of CO2 adsorption and separation in IL-ZIF-IL composites with shell-interlayer-core structure

Development of materials with excellent separation performance remains an ongoing challenge in separation science and technology. Herein, a novel strategy was proposed to gradually enhance gas separation performance in micro/nano-materials, by constructing a shell-interlayer-core structure using ionic liquid (triethylenetetramine lactate, [TETA]L) and zeolitic imidazolate framework (ZIF-8). Such structure includes outer [TETA]L shell, interlayer of ZIF-8, and inner [TETA]L core, endowing the composite with more evident molecular sieving separation for CO₂ mixtures than the reported materials. A high CO₂ adsorption amount (1.53 mmol/g at 298 K and 1.0 bar) is maintained, while the uptakes for CH₄ and N₂ are very low. Corresponding ideal adsorbed solution theory selectivities are 260–1,990 and 1,688–5,572 for CO₂/CH₄ and CO₂/N₂ mixtures at the range of tested pressures. In addition, the separation performance can be controlled by varying the shell-interlayer-core structure with IL inside, outside or on both sides of ZIF-8 and the thickness of outer shell.     

Enhancing flame retardant and antistatic properties of polyamide 6 by a grafted multiwall carbon nanotubes

In order to improve the flame retardancy and antistatic properties of polyamide 6 (PA6) at as low amount of additives as possible, an integrated-functional additive was synthesized by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and multiwalled carbon nanotubes (MWCNTs). The results showed 2 wt% of DOPO-MWCNTs distributed in PA6 formed an electric network and decreased volume resistivity sharply to 3.1 × 10⁸ Ω cm. In other words, it helped PA6 to get to the percolation threshold of semiconductor. By using of 3 wt% DOPO-MWCNTs, the severe dripping in burning of PA6 was almost controlled. The possible reason was also ascribed to the network formed by evenly dispersed DOPO-MWCNTs, which strengthened the char structure and held severe dripping of PA6. As a result, the heat and smoke release were also suppressed obviously. The most important is that CO release was about half cut in CONE test.     

Doped/Undoped A1-A2 Typed Copolymers as ETLs for Highly Efficient Organic Solar Cells

The electron transport layer (ETL) is a critical component in achieving high device performance and stability in organic solar cells. Conjugated polyelectrolytes (CPEs) have become an attractive alternative due to film-forming properties and ease of preparation. However, p-type CPEs generally exhibit poor charge mobility and conductivity, incorporation of electron-withdrawing units forming alternated D-A conjugated backbone can make up for these deficiencies. Herein, the ratio of electron withdrawing moieties are further increased and two poly(A1-alt-A2) typed PIIDNDI-Br and PDPPNDI-Br based on the combination of naphthalene diimide (NDI) with isoindigo (IID) or diketopyrrolopyrrole (DPP) via direct arylation polycondensation are synthesized. These CPEs possess excellent alcohol solubility, a suitable lowest unocuppied molecular orbital energy level, and work function tunability. Surprisingly, the incorporation of IID and DPP units generate distinct self-doping behaviors, which are confirmed by UV–vis absorption and ESR spectra. However, no matter doped or undoped, both CPEs present better charge-transporting properties and conductivity when utilized as ETLs. The PIIDNDI-Br and PDPPNDI-Br display good universal compatibility with the blend of PM6:Y6 and PM6:L8-BO, and PCEs of 18.32% and 18.36% are obtained, respectively, which also present excellent storage stability. In short, the combination of two different acceptors demonstrates an efficient strategy to design highly efficient ETLs for high performance photovoltaic devices.     

Ni3N–CeO2 Heterostructure Bifunctional Catalysts for Electrochemical Water Splitting

Developing low-cost and high-efficient bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is greatly significant for water electrolysis. Here, Ni₃N-CeO₂/NF heterostructure is synthesized on the nickel foam, and it exhibits excellent HER and OER performance. As a result, the water electrolyzer based on Ni₃N-CeO₂/NF bifunctional catalyst only needs 1.515 V@10 mA cm⁻², significantly better than that of Pt/C||IrO₂ catalysts. In situ characterizations unveil that CeO₂ plays completely different roles in HER and OER processes. In situ infrared spectroscopy and density functional theory calculations indicate that the introduction of CeO₂ can optimizes the structure of interface water, and the synergistic effect of Ni₃N and CeO₂ improve the HER activity significantly, while the in situ Raman spectra reveal that CeO₂ accelerates the reconstruction of O_V (oxygen vacancy)-rich NiOOH for boosting OER. This study clearly unlocks the different catalytic mechanisms of CeO₂ for boosting the HER and OER activity of Ni₃N for water splitting, which provides the useful guidance for designing the high-performance bifunctional catalysts for water splitting.     

聚丙烯腈原丝预氧化过程中长周期结构的生成

通过在线实时采集预氧化过程中聚丙烯腈纤维二维小角X射线散射(SAXS)花样,利用环化反应导致的电子云密度改变产生的SAXS谱图变化,研究亚微米结构在环化结构形成过程中的温度依赖性。根据所建立的环化及未环化的两相模型,在对散射信息中的微孔结构和长周期结构的叠加信号进行合理分离的基础上,研究了预氧纤维中长周期结构的生成和演变过程。结果表明,预氧化初期产生的环化相与非环化相呈现周期性结构堆砌,并随着温度的进一步升高逐渐趋于均一体系。同时结合相关函数分析方法,计算了长周期结构中环化相和非环化相厚度等结构参数,提出了预氧化程度的小角X射线散射定量表征的方法。     

高强高模碳纤维表面电化学氮化机制

高温石墨化使高强高模碳纤维(CF)表面光滑,反应活性低,导致其复合材料界面粘接性能差。杂原子改性是改善CF表面反应活性的有效手段之一。采用循环伏安(CV)方法在有机复合电解液中对高强高模CF进行了表面氧化和氮化改性,采用CV优选的复合电解液进行恒流电化学氧化处理,研究了CV扫描次数和电解液中含氮有机物对CF表面化学组成的影响。电化学处理前后CF表面化学元素组成和微观形态变化通过XPS、SEM及拉曼光谱表征。基于实验数据探讨了CF表面含氮官能团的生成及转变机制。研究结果显示,有机溶剂、有机氮源和含硫铵盐的协同作用使CF表面N含量从0.28at%增至4.77at%。适量的水存在,可以使CF表面O含量显著提高。CF表面的含氧官能团可以与CO(NH₂)₂中的-NH₂及电解液中的NH₄⁺反应形成酰胺基团,随着反应时间延长,CF表面的酰胺N会先转变成氧化氮,随后转变成吡啶和吡咯N,并最终转换成石墨N。恒流电化学处理后CF/环氧树脂复合材料的层间剪切强度(ILSS)较未处理的提高了132%,...