Additives are one of the important means to improve the performance of perovskite solar cells. To explore the effects of different addition methods on the crystallinity of perovskite, in this paper, guanidine thiocyanate (GASCN) is added in three different methods, i.e., added in SnO 2 precursor solution; in PbI 2 precursor solution; or FAI precursor solution, respectively. The guanidine hydroiodide (GAI) and methylamine thiocyanate (MASCN) are selected as contrast additives to evaluate the role of GA + and SCN − . Though the efficiency and stability of the perovskite solar cells with all additives are improved, the systematic study by grazing incidence wide‐angle X‐ray scattering (GIWAXS), quasi‐in situ GIWAXS, and in situ X‐ray diffraction (XRD) proved that the mechanism by the three different addition methods behaved in many different ways, which corresponded, respectively, to the surface of the SnO 2 electron transport layer, dominance orientation especially vertical growth of perovskite, or low‐dimensional perovskite structure. This provides a new view for optimizing the appropriate synthesis conditions in the future.

Quasi-2D perovskites show great potential as photovoltaic devices with superior stability, but the power conversion efficiency (PCE) is limited by poor carrier transport. Here, it is simultaneously affected the hole transport layer (HTL) and the perovskite layer by incorporating pyridine-based materials into poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) to address the key problem above in 2D perovskites. With this approach, the enhanced optoelectronic performance of the novel PEDOT:PSS is due to electron transfer between the additives and PEDOT or PSS, as well as a dissociation between PEDOT and PSS based on experimental and theoretical studies, which facilitates the charge extraction and transfer. Concurrently, in-situ X-ray scattering studies reveal that the introduction of pyridine-based molecules alters the transformation process of the perovskite intermediate phase, which leads to a preferred orientation and ordered distribution caused by the Pb─N chemical bridge, achieving efficient charge transport. As a result, the pyridine-treated devices achieve an increased short-circuit current density (Jsc) and PCE of over 17%.

New binary carbon composites (GDY-NCNTs and GDY-CNTs) with a three-dimensional porous structure, which are synthesized by an in situ growth method, are adopted in this article. The GDY-NCNTs composites exhibit excellent specific capacitance performance (679 F g(-1), 2 mV s(-1), 139% increase compared to GDY-CNTs) and good cycling stability (with a capacity retention rate of up to 116% after 10000 cycles). The three-dimensional porous structure not only promotes ion transfer and increases the effective specific surface area to improve its specific capacitance performance but also adapts to the volume expansion and contraction during the charging and discharging process to improve its cycling stability. The presence of nitrogen doping in the carbon nanotubes of GDY-NCNTs increases the surface defects of the composites, provides more electrochemical points, and improves the surface wettability of the composites, further improving the electrochemical performance of the composites.

As a typical carbon nanomaterial, graphdiyne (GDY) is expected to contribute to the field of nanozymes due to its unique structure and properties. However, the limited intrinsic enzyme-like activity of the pristine GDY nanomaterial suppressed its further development and application. In this paper, a heteroatom (Fe and N)-doping strategy was adopted to prepare GDY-based nanozymes. It has been found that heteroatom doping can improve the peroxidase-like activity of GDY nanomaterials, especially when Fe and N are codoped. The codoping of Fe and N not only increased the number of active sites, which could be uniformly distributed on the carbon substrate because of the coordination of N and Fe, but also changed the reactivity of substrates with nanozymes. As a result, the peroxidase-like activity of the Fe1.5-N-GDY nanozyme after the codoping of Fe and N into GDY was 18 times that of the N-GDY nanozyme and 14 times that of the Fe-1.5-GDY nanozyme. Moreover, the sensing application of the Fe-1.5-N-GDY nanozyme was explored in the determination of H2O2 and ascorbic acid (AA) through colorimetric assays, while the linear relationship was 100-800 and 800-2000 mu M with a detection limit of 52.96 mu M for H2O2 and was 5-100 mu M with a detection limit of 5.95 mu M for AA. This work provides not only an excellent peroxidase-like nanozyme for sensing but also a valuable reference for the design and synthesis of GDY-based nanozymes.

In this paper, a three-dimensional (3D) network Ag/MnO2/GO/PPy nanocomposite with adjustable micro-mesoporosity was synthesized by effectively controlling the amount of added pyrrole (Py). The Ag/MnO2/GO/PPy-5 nanocomposite exhibits excellent specific capacitance (C = 474.3 F g(-1), 5 mV s(-1)) and high cycle stability (up to 105.3% efficiency after 10,000 charge/discharge cycles). The appropriate micro-mesoporous structure of the 3D graphene-based nanocomposite provides a low-resistance path and a shorter diffusion path for ions, remarkably improving the electrochemical performance of Ag/MnO2/GO/PPy-5 by combining the advantages of these materials. Moreover, the 3D porous structure has strong stability, and evenly dispersed MnO2 and symbiose Ag nanoparticles can afford additional active sites and high conductivity for the nanocomposites.

As one of the typical carbon nanomaterials, graphdiyne (GDY) with unique chemical, physical, and electronic properties has a great potential in various fields. Although it is an important member of carbon nanozymes, the research on its intrinsic enzyme mimetic properties and applications is still limited. Herein, graphdiyne oxide quantum dots (GDYO QDs) have been synthesized through oxidative cleavage, which exhibit enhanced peroxidase-like activity with lower Km and higher Vmax than those of most carbon-based nanozymes. The catalytic mechanism is explored, showing that the enhanced catalytic performance is attributed to the good conjugated structure, large number of oxygen-containing groups, and small-sized nanosheets with few layers. As a kind of peroxidase mimetic, the GDY-based nanozyme has excellent potential in sensing H2O2 and biological antioxidants through the colorimetric assay, with a linear range from 5 to 500 μM and detection limit of 1.5 μM for H2O2 and a linear range from 0 to 90 μM and detection limit of 0.48 μM for l-cysteine. Our work will be beneficial to develop high-performance artificial enzymes and to understand their mechanism for better applications.

Herein, strong oxidants are employed for the first time to stabilize the main frame structure of the perovskite [PbI6]4− by strengthening the interaction between the central Pb atom and coordination I atoms. A systematic study on the microstructure and macrostate of the perovskite is carried out by the synchrotron radiation technique and conventional characterization. According to the valence state and local environment of each chemical element, crystallinity and morphology of the active layer, and photoelectric properties of the solar cell, the strong oxidants, tris[2‐((1H‐pyrazol‐1‐yl)‐4‐tert‐butylpyridine)cobalt(III)tris(bis(trifluoromethylsulfonyl)imide)] (FK209) and Na2S2O8, can increase the power conversion efficiency and stability of the doped devices. A possible mechanism of doping strong oxidants is explained.

Graphdiyne-based materials are promising candidates for the adsorption and detection of heavy metal ions (HMIs) as the acetylenic links in graphdiyne strongly interact with some metal ions. To improve the sensing performance of graphdiyne-based materials and further understand their detection mechanism, we prepared N-substituted graphdiyne (TGDY) through bottom-up method as electrode modified materials, which contained position-fixed and content-controlled alkynyl bonds and pyridine N atoms. By comparing with the H-substituted graphdiyne (HGDY), which was roughly the same in structure as TGDY except that the benzene ring without N atoms, we found that the introduction of N in TGDY greatly improves the electrochemical performance and the signal intensity is closely related to the number of detection sites. Furthermore, the performance of TGDY-based electrochemical sensor was also explored, which showed satisfactory selectivity, reproducibility, stability and applicability for the detection of Cd2+ and Pb2+ in water. Our work provided an important reference for rational design and synthesis of electrode materials through bottom-up method to improve the detection performance and explore the detection mechanism.

In this work, graphdiyne, a new kind of carbon allotrope composed of sp and sp(2) hybridized carbon atoms, firstly worked as an effective electrochemical sensor for the determination of low concentration of Cd2+ and Pb2+ in water using electrochemical pre-enrichment and anodic-stripping voltammetry methods. The limit of detection was 0.46 nM for Cd2+ and 1.72 nM for Pb2+ with a linear range extended from 0.01 mu M to 1 mu M. This graphdiyne modified electrode also presented excellent selectivity, stability, applicability and reproducibility, providing a simple and promising platform to develop novel electrochemical sensor for detecting Pb2+ and Cd2+ with higher performance. Through X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) and X-ray absorption near edge structure (XANES) characterization, it was verified that the acetylenic links in graphdiyne served as adsorbent sites by providing electrons to bind with heavy metal ions, which enhanced the electrochemical sensing performance.

The build-in hypoxia-driven dual reporter 9HRE-HSV1-TKeGFP hypoxia research model does not modify intrinsic radiosensitivity of SUNE1 cells under the condition of normoxia or hypoxia, suggesting it be used as preclinical model to explore the therapeutic efficacy of various treatment modalities to overcome hypoxia by fluorescence or nuclear imaging techniques.

The electron spin characters of paramagnetic endohedral metallofullerenes (EMFs) are sensitive to their surroundings, which offer an opportunity to manipulate their paramagnetic properties. Here we reported the amination of paramagnetic Gd@C-82 and revealed that morpholine groups can be used as a tool to fine-tune properties of Gd@C-82. Changes of their paramagnetic properties have been observed under different temperatures and among three derivatives. Addition of morpholine groups eliminates the single unpaired electron on the carbon cage, and causes lower symmetry of the carbon cage and location limit of encapsulated gadolinium, leading serious restriction of Gd@C-82 and gadolinium motion. The high sensitivity of spin population to chemical modification offers us the possibility to investigate the spin qubit property and further realize quantum control on a molecular level. (C) 2019 Elsevier Ltd. All rights reserved.

Tumor hypoxia, a common phenomenon in solid neoplasms has been associated with aggressive malignant phenotypes and resistance to chemo- and radiotherapy. The purpose of the study was to investigate the effect of carbogen on oxygenation status in tumoral and muscular tissues by direct probe pO2 measurement, to compare the difference of hypoxia biodistribution by imaging exogenous and endogenous hypoxia markers and to explore potential hypoxia-modifying modality to enhance the effect of radiotherapy. BALB/c-nu/nu nude mice were used as tumor-bearing host. pO2 measurements in tumoral and muscular tissues were initiated at the time of probe insertion and the values were recorded continuously for at least 60 min using the fiber-optic oxygen-sensing device (OxyLiteÔ Oxford Optronix, UK) when the tumor-bearing host was under anesthesia which was accomplished with a gas mixture containing 1.0% isoflurane balanced by either air (21% O2) or carbogen (95% O2 + 5% CO2). Image study with CA IX and exogenous hypoxia markers including pimonidazole and EF5 was used to evaluate the effect of spatial biodistribution when animals were treated with air- and carbogen-breathing. Hypoxia in tumor is heterogeneously observed in solid tumors when animal breathing air by using probe pO2 measurement or image study, whereas it ameliorated when breathing carbogen. 4 patterns of pO2 response in tumor can be subcategorized as: i) immediate response, ii) moderate immediate response, iii) slow response and iv) no response when animal was switched from air to carbogen breathing; while 2 patterns, i.e., immediate or no response in muscular tissue are observed. pO2 values in tumoral tissue may remain at relatively higher level at 30 or 60 minutes when the breathing gas was switched from carbogen to air than that of the baseline at initial air breathing; while pO2 value in muscular tissue at air breathing switched from carbogen returned to the same level of baseline at initial air breathing. Tumor hypoxia existed heterogeneously within tumor tissues thus could be subcategorized into 4 patterns according to the pO2 response to carbogen breathing. The observation that pO2 value may remain at relatively high level when air breathing was switched from carbogen in comparison to the baseline at initial air breathing may provide a potential modality that radiation therapy may benefit immediately after carbogen-breathing by improved oxygen status in tumor but not in muscular tissue thus may enhance the therapeutic index. Further research should be merited.

The nitrogen-doped holey graphene oxide/TiO2 (TiO2-NHGO) composite is synthesized as catalyst support for the Pt catalyst. The resulting catalyst, Pt-TiO2-rNHGO, shows higher activity and stability for methanol electrooxidation than the Pt-rGO, Pt-rHGO, and Pt-rNHGO catalysts. The enhancement is because of the combinatory effect of nanoholes in the graphene plane which provide more active sites and efficient mass transport, well-distributed N-doping, and the uniform distribution of TiO2 NPs on NHGO nanosheets which facilitate to form more uniformly dispersed Pt NPs. In addition, the strong interactions among Pt, TiO2, and NHGO also contribute to enhance the performance of catalyst for methanol oxidation.

In this work, a novel chelating adsorbent, 2, 4-dithiobiuret-reduced graphene oxide composite (DTB-RGO), was synthesized and worked as an electrochemical sensor for the determination of Pb2+. X-ray photoemission spectroscopy, Raman spectroscopy and Fourier transform-infrared spectroscopy were used to confirm the successful doping of the aminothiourea groups into the GO nanosheets through amide bond. The electrode modified with DTB-RGO shows two wide linear range 0.1-200 ng mL(-1), 200 -1000 ng mL(-1) and relatively low detection limit 0.08 ng mL(-1) for Pb2+, far below the level of 10 ng mL(-1) proposed by WHO. This DTB-RGO modified electrode also presents satisfying selectivity, reproducibility, stability, and applicability for detection of Pb2+, providing a simple and promising platform to develop novel electrochemical sensor for detecting Pb2+ with higher performance. (C) 2020 Elsevier B.V. All rights reserved.

The crystal structure of perovskite has a significant influence on the photovoltaic performance and stability of perovskite solar cells (PSCs). Pb4+ is introduced into CH3NH3PbI3 (MAPbI(3))-based PSCs by participating the octahedral [PbI6](4-) structure, then to induce the formation of stronger Pb-I bond and reduce [PbI6](4-) octahedron distortion, which would improve structural symmetry, decrease the degree of disorder and be beneficial to the crystallization of perovskites. Synchrotron based X-ray absorption fine spectroscope (XAFS) revealed that the existence of higher valence state lead could be realized by doping Pb4+ directly or induced by electron withdrawing group, in consequence the [PbI6](4-) octahedral structure becomes more stable. Grazing incidence X-ray diffraction (GIXRD) especially demonstrates that Pb4+ with appropriate proportion may well replace part of Pb2+ to form an uniform phase in the primal perovskite structure to improve the crystallization on the surface and homogeneous out-of-plane (OOP) ordered crystal accumulation in the bulk, which is also important for improving the efficiency and stability of PSCs. As a result, a power conversion efficiency (PCE) exhibits a 42.1% increase with the doping of 0.03% PbF4 and 0.075% PCBM compared with a pristine device and its stability improves markedly after 30 days of storage in ambient atmosphere.

In this work, three-dimensional graphene aerogels have been prepared by introduction of pyrrole to regulate their structure and properties and used as electrode materials to investigate the special role of pyrrole for sensing metal ions. The interaction between pyrrole and graphene oxide is explored through a series of characterization techniques to understand the role of doped pyrrole. Besides as N source to provide active metal ions binding sites, pyrrole can also serve as a reductant and a regulator to adjust the composition and structure of graphene aerogels, which greatly influences their electrochemical performance of sensing Cd(II). And, the reaction ratio of pyrrole and graphene oxide plays a key role to optimize the effect of pyrrole. By the method of square wave anodic stripping voltammetry (SWASV), the 3DGO-Py10 modified electrode can be successfully applied to determine Cd(II) in aqueous solutions. These findings will provide new guidelines to design electrode materials for heavy metal ions detection.

In this paper, a superior supercapacitor nanocomposite based on porous carbon nanotubes (PCNTs), MnO2/PCNT/MnO2, was synthesized, which displayed superior specific capacitance (C = 341.5 F g(-1), 2 mV s(-1)), excellent rate capability (C = 214.3 F g(-1), 63% capacity retention, 100 mV s(-1)), and high cyclic stability (98% efficiency after 6000 charge/discharge cycles). The outstanding improvement of its electrochemical performances resulted from the massive nanopores on the walls of PCNTs, which made more MnO2 nanoparticles filled both in the nanocavity and on the surface of PCNTs as electroactive sites. At the same time, PCNTs improve the electrical conductivity with the pore structure being beneficial to ion exchange, they shorten the ion transport distance, and adjust to the volume expansion and contraction among charge/discharge. In addition, the Mn(IV)/Mn(III) redox electric pair in the nanocavity enhances the capacity storage. Therefore, the MnO2/PCNT/MnO2 nanocomposite shows higher specific capacitance and excellent cyclic stability.

In this study, the stability mechanism of the optimized methyl ammonium lead triiodide (CH3NH3PbI3, MAPbI3)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) perovskite active layer upon exposure to moisture, light, and heating was investigated.

Dual mode imaging technology is widely developed to achieve the early-stage precision cancer diagnosis. Here we designed a dual-modal magnetic resonance/near infrared fluorescence optical imaging contrast agent (GdF-SS-NIR783) with the fluorescence activatable and safer gadofullerene. The nanoprobes were fabricated by conjugating the gadofullerene derivatives with a NIR fluorescence imaging agent (NIR783) via the disulfide bond. The obtained nanoprobes showed no fluorescence (OFF), but the fluorescence turned on when incubated within reduction environment such as GSH solution. The clear fluorescence signal in tumor site was observed obviously after their intratumor injection. The nanoprobes also revealed efficient MRI contrast enhancement both in vitro and in vivo. And they showed good biocompatibility and did not demonstrate any tissue toxicity in vivo. This work gave the new possibility in designing more efficient and safer nanoprobes for future medical diagnoses.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTRegioselective Polyamination of Gd@C2v(9)-C82 and Non-High Performance Liquid Chromatography Rapid Separation of Gd@C82(morpholine)7Huan Huang†⊥, Lele Zhang∥⊥, Xuejiao J. Gao‡, Xihong Guo†, Rongli Cui†, Binggang Xu#, Jinquan Dong†, Yanbang Li§, Liangbing Gan§, Fei Chang∥, Xingfa Gao*‡, and Baoyun Sun*†View Author Information† CAS Key Lab for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China‡ Key Laboratory of Functional Small Organic Molecule, Ministry of Education, and Jiangxi's Key Laboratory of Green Chemistry, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China§ College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China∥ College of Chemistry and Chemical Engineering, Inner Mongolia University, Huhhot 010021, China# School of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, China*Baoyun Sun. E-mail: [email protected]*Xingfa Gao. E-mail: [email protected]Cite this: Chem. Mater. 2018, 30, 1, 64–68Publication Date (Web):December 15, 2017Publication History Received8 September 2017Revised15 December 2017Published online20 December 2017Published inissue 9 January 2018https://pubs.acs.org/doi/10.1021/acs.chemmater.7b03787https://doi.org/10.1021/acs.chemmater.7b03787rapid-communicationACS PublicationsCopyright © 2017 American Chemical SocietyRequest reuse permissionsArticle Views1003Altmetric-Citations8LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (2)»Supporting Information Supporting Information SUBJECTS:Adducts,Carbon,Carbon nanomaterials,Molecular structure,Nanospheres Get e-Alerts