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Despite huge efforts have been devoted to investigating ultrathin layers of two-dimensional (2D) transition-metal dichalcogenides (TMDs), their realistic applications in electronics and optoelectronics are hindered by limited scalability and uniformity of 2D thin layers. In this work, a two-step synthesis method was adopted to produce wafer-scale molybdenum diselenide (MoSe2) nanosheets. Molybdenum oxide (MoO3) thin film was initially prepared via atomic layer deposition (ALD) and followed by a selenization process in chemical vapor deposition (CVD) tube furnace. MoSe2 nanosheets with desired thickness can be obtained by tuning ALD cycles in preparing MoO3 layers. The synthesized MoSe2 films exhibited excellent layer controllability, homogeneity and wafer-scale uniformity. Few-layer structure of our MoSe2 with a polycrystalline crystal structure was verified by means of Raman and transmission electron microscopy (TEM) measurements. Moreover, arrays of MoSe2-based photodetectors with different device dimension were fabricated and the photo-responses of the devices were studied. The device exhibited a fast photo-response time of 50 ms, a high on/off ratio of ~ 24 and a good photo-responsivity of 11.7 mA/W, and it is found that the effective illumination area was a critical factor for application. The work opens up an attractive approach to realize the application of wafer-scale 2D materials in integrated optoelectronic-systems. [ABSTRACT FROM AUTHOR]

Radical salts and charge-transfer complexes (CTCs) containing tetracyanoquinodimethane (TCNQ) display electrical conductivity, which has led to the development of many TCNQ derivatives with enhanced electron-accepting properties that are applicable toward organic electronics. To expand the family of TCNQ derivatives, we report the synthesis and structures of 11,11,12,12-tetracyano-2,6-diiodo-9,10-anthraquinodimethane (abbreviated as DITCAQ), C20H6I2N4, and its charge-transfer complexes with various electron donors, namely DITCAQ-anthracene (2/1), C20H6I2N4·0.5C14H10, (I), DITCAQ-pyrene (2/1), C20H6I2N4·0.5C16H10, (II), and DITCAQ-tetrathiafulvalene (2/1), C20H6I2N4·0.5C6H4S4, (III). The molecular structure of DITCAQ consists of a 2,6-diiodo-9,10-dihydroanthracene moiety with two malononitrile substituents. DITCAQ possesses a saddle shape, since the malononitrile groups bend significantly up out of the plane of the central ring and the two benzene rings bend down out of the same plane. π-π interactions between DITCAQ and the electron-donor molecules control the degree of charge transfer in cocrystals (I), (II), and (III), which is reflected in both the dihedral angles between the terminal benzene ring and the central ring on the DITCAQ motifs, and their corresponding IR spectra. [ABSTRACT FROM AUTHOR]

Maleic anhydride (MAH) grafting to different polyolefins with similar grafting degree can have different effects on crystallization, crystal structure, and mechanical and thermal properties. The grafting leads to a smaller crystal size, less ordered lamellar structure, and a shorter long period for HDPE, LLDPE, and PP. The grafting makes PP lamellar packing less ordered the most and almost no effect to LLDPE. The grafting does not have that much impact on the crystallization ability of the HDPE, LLDPE, and HDPE/PP blend, but appreciably reduces the crystalline ability of PP-g-MAH, due to a dramatical drop in its molecular weight during the grafting process. As a result, the grafting makes PP a very brittle material with a lowered average melting point than the corresponding neat PP, but the grafting has almost no effect on elongation at break for LLDPE and some effect on HDPE (decreased by one-third). However, the PP degradation due to MAH grafting can be avoided in the presence of PE component, i.e., making the grafting of PP and PE at the same time with HDPE/PP blend. The grafted HDPE/PP blend shows a significantly improved compatibility, which leads to overall appreciably better mechanical properties than the neat HDPE/PP blend. [ABSTRACT FROM AUTHOR]

Both the ≡Fe(III) reduction and the catalyst stability are the main obstacles limiting the application of such Fe-doped Fenton-like catalysts in endocrine disruptors removal. Herein, oxygen was introduced to the Fe-g-C 3 N 4 to fabricate a newly Fe–O-doped catalyst FeCA-g-C 3 N 4. The pseudo-first-order rate constant for bisphenol A (BPA) degradation in FeCA-g-C 3 N 4 system is 2.6 times higher than that in the traditional Fe-doped g-C 3 N 4 (FeCl 3 -g-C 3 N 4) system. And the formation of Fe–O bond can strengthen the stability of the catalyst. After operating 400 h, the π conjugate plane in the FeCl 3 -g-C 3 N 4 was completely destroyed, and the degradation of BPA was less than 3%. However, the crystal structure of FeCA-g-C 3 N 4 was relatively intact, and the degradation of BPA was still above 90%. According to the XPS and EXAFS spectra, the improvement of the FeCA-g-C 3 N 4 stability was attribute to the shorter lengthen of the Fe–O bond (1.47 Å). Besides, the introduction of electron-rich oxygen center can also effectively promote the reduction of ≡Fe(III) and directly activated H 2 O 2. Additionally, the electron-rich oxygen will also alleviate the shielding effect of halogen ions on the Fe sites, and the low concentration (<0.01 mM) of halide ions could even promote H 2 O 2 activation by 12.2%–24.5%. In conclusion, this study provides new insights to strengthen catalyst stability and accelerate electron transfer in the Fenton-like process, promoting its application in the actual wastewater purification. [Display omitted] • Fe–O-doped g-C 3 N 4 catalyst was fabricated by using ferric citrate as iron source. • Oxygen center can directly activate H 2 O 2 through single electron transfer. • Formation of Fe–O bond greatly improves the stability of the catalyst. • Oxygen center can improve the anti-interference ability of the catalyst. [ABSTRACT FROM AUTHOR]