Graphical abstract

Doping ordered mesoporous carbon with electron-donating nitrogen and sulfur heteroatoms is a promising strategy to enhance its electrochemical performance. Here we demonstrate the successful fabrication of nitrogen and sulfur co-doped ordered mesoporous carbon (NSOMC) materials with high specific surface areas (978-1021 m 2 g À1 ), large pore volumes (1.10-1.20 cm 3 g À1 ), highly-ordered pore structures and controlled dopant contents (10.0-4.8 at.% for nitrogen and 1.7-2.6 at.% for sulfur) using the oligomer of pyrrole as the precursor and sulphuric acid as the catalyst and sulfur source. NSOMC materials exhibit enhanced electrochemical double-layer capacitance (EDLC) performances due to their improved surface activity and conductivity compared with pure carbon CMK-3. The fabrication of nitrogen and sulfur co-doped ordered mesoporous carbon with enhanced electrochemical capacitance performance provides a viable route to promote its applications in electronic devices.

In this contribution, nitrogen- and sulfur-codoped 3D cubic-ordered mesoporous carbon (KNOMC) materials with controlled dopant content (10.0-4.6 atom % for nitrogen and 0.94-0.75 atom % for sulfur) are presented, using KIT-6 as the template and pyrrole as the precursor, and its supercapacitive behavior is also investigated. The presented materials exhibit excellent supercapacitive performance by combining electrical double-layer capacitance and pseudocapacitance as well as the enhanced wettability and improved conductivity generated from the incorporation of nitrogen and sulfur into the framework of carbon materials. The specific capacitance of the presented materials reaches 320 F g(-1) at a current density of 1 A g(-1), which is significantly larger than that of the pristine-ordered mesoporous carbon reported in the literature and can even compete with some metal oxides and conducting polymers.

Dynamic shear deformation of a CrCoNi medium-entropy alloy with heterogeneous grain structures, Acta Materialia (2018), AbstractSingle-phase CrCoNi medium-entropy alloys (MEA) are emerging recently as an interesting class of metallic materials, but the dynamic response of this MEA at high strain rates remains unknown. Here we have produced this MEA with various heterogeneous microstructures, using cold rolling followed by annealing at various temperatures. The high-strain-rate response of the MEAs was characterized using hat-shaped specimens in Hopkinson-bar experiments. A combination of high dynamic shear yield strength and large uniform dynamic shear strain was observed, exceeding all other metals and alloys reported so far. Even better dynamic shear properties was revealed when the experiments were conducted at cryogenic temperature. The strong strain hardening under dynamic shear loading can be attributed to the dynamic grain refinement and deformation twinning that accompany the homogeneous shear deformation. When compared to room temperature, the efficiency of grain refinement was found to be enhanced at cryogenic temperature, with a higher density of multiple twins, stacking faults, Lomer-Cottrell locks, and hcp phase via phase transformation inside the grains, which could be responsible for the better dynamic shear properties under cryogenic environment.partitioning and strain gradients have been found to play an important role during the tensile deformation in heterogeneous structures, resulting in back stresses that enhance extra strain hardening and uniform elongation. This strategy can also be used for metals and alloys with ultra-low SFE, such as HEAs and MEAs.The un-dissipated plastic work leads to appreciable temperature rise such that the