Enhancement of photocatalytic by Mn3O4 spinel ferrite decorated graphene oxide nanocomposites

The hydrothermal process was used to prepare Mn3O4/x%GO nanocomposites (NC’s) having different ratios of the Mn3O4 nanoparticles (NP’s) on the surface of graphene oxide (GO) sheet. SEM image showed that the Mn3O4 NP’s were distributed over the surface of GO sheet. HRTEM images exhibited the lattice fringe arising from the (101) plane of the Mn3O4 NP’s having the interplanar d-spacing of 0.49 nm decorating on the surface of GO. The electronic absorption spectra of Mn3O4/x%GO NC’s also show broad bands from 250 to 550 nm. These bands arise from the d–d crystal field transitions of the tetrahedral Mn3+ species and indicate a distortion in the crystal structure. Photo-catalytic activity of spinel ferrite Mn3O4 NP’s by themselves was low but photo-catalytic activity is enhanced when the NP’s are decorating the GO sheet. Moreover, the Mn3O4/10%GO NC’s showed the best photo-catalytic activity. This result comes from the formation of Mn–O–C bond that confirm by FT-IR. This bond would facilitate the transfer of the photoelectrons from the surfaces of the NP’s to the GO sheets. PL emission which is in the violet–red luminescent region shows the creation of defects in the fabricated Mn3O4 NP’s nanostructures. These defects create the defect states to which electrons in the VB can be excited to when the CB. The best degradation efficiency was achieved by the Mn3O4 NP’s when they were used to decorate the GO sheets in the Mn3O4/10%GO NC’s solution. Highlights Lattice fringe of Mn3O4 with an interplanar d-spacing of 0.49 nm for (101) plane. Photocatalytic activity of spinel ferrite Mn3O4 nanoparticles by itself is low. Number of photoelectrons created depends on number of Mn3O4 on a given area of GO The bonding of the Mn3O4 to the GO sheet would be though a Mn–O–C junction. The degradation processes were accelerated by Mn3O4/10%GO nanocomposites Graphic abstract

Macromolecular Structural Responses of Coking Coal to Stress–Strain Environments Based on High-Resolution Transmission Electron Microscopy

In China, most coal seams have experienced multiple phases of tectonics, which increase the complexity of the coal porosity. The responses of macromolecular structures to stress–strain environments are the key to understanding the complexity of coal porosity caused by tectonism. This study investigated the macromolecular structural response of coking coal to different stress–strain environments. The calculation and analysis of high-resolution transmission electron microscopy (HRTEM) test results for six coking coals with different deformation types and degrees were performed. The results showed that the macromolecular structure of coking coal has different responses to stress– strain environments. The lattice fringe length, curvature, and d002 parameters are not prominently governed by certain principles increasing shear and toughness. Furthermore, the lattice fringe tends to be consistent with the deformation. However, the lattice fringe during ductile deformation in the main direction is arranged nearly parallel on the plane. In shear deformation, the lattice fringes are arranged parallel in the principal direction. This phenomenon is caused by the directional screening of the macromolecular structure of coking coal by stress. Under the action of tectonic stress, the structure hindering tectonic stress is destroyed, and the structure grows in other directions gradually under the promotion of tectonic stress. As a result, the direction of the whole lattice fringe gradually converges under stress screening after tectonic stress is applied. Therefore, the direction tends to be consistent with the strengthening of the deformation. The response of the other parameters is slow, showing the coexistence of the old and new orders of direction. The directivity of the macromolecular structure of coal is an important index for reflecting the types and degrees of tectonic deformation.

Liquid like nucleation in free-standing nanoscale films

Nanoscale free-standing solid films show liquid like nucleation behaviour (). The concept of 'depth sensitive lattice fringe imaging' is introduced.