In this paper, wheat straw was converted into nitrogen-doped hierarchical porous carbon (N-HC) by direct pyrolysis of wheat straw with CaCl 2 as an activator and melamine as a nitrogen resource. The as-prepared samples exhibit different hierarchical porous structures and nitrogen contents in a temperature range from 600 to 800 °C. Compared with other samples, the N-HC-800 displays a large amount of micropores, uniform mesopores, a high specific surface area (892 m 2 g −1 ), and moderate nitrogen doping (5.63 wt %). Therefore, the N-HC-800-based supercapacitor exhibits a high specific capacitance of 275 F g −1 at a current density of 0.2 A g −1 , a high capacitance retention ratio of 81% even at 8 A g −1 , and an excellent cycling stability (over 97% retention rate after 10 000 cycles) in 6 M KOH solution. This work not only proposes a novel routine for the development of porous carbon materials for supercapacitor but also provides a new option for the processing of waste wheat straw instead of being burned in rural areas.

Molten inorganic salts containing solid nanoparticles with a stable and uniform dispersion have attracted great attention as efficient heat transfer and storage materials 1,2 and for catalysis for chemical reactions [3][4][5] . Electrophoretic deposition in molten inorganic salts containing nanoparticles, have not been reported in the literature, compared with the related wide investigations in aqueous and organic suspensions 6,7 . Here we report the possibility of electrophoretic deposition of nanoparticles in high-temperature molten salts. In molten fluorides and chlorides, cell voltages of 1.2-1.5 V below the decomposition voltage of the electrolytes, were applied to perform the electrophoretic deposition of nanoparticles (e.g., TiB2 and ZrB2) on different cathode substrates, resulting in compact and adhesive coatings with high hardness. These findings should present opportunities to synthesize additional coatings and films via the proposed process.

In this work, remelted high carbon ferromanganese was chosen as a consumable anode to produce porous carbon monolith and low carbon ferromanganese at the same time by molten salt electrolysis. During potentiostatic electrolysis, the anode fed manganese ions and iron ions into molten salts, with porous carbon left at the anode and ferromanganese deposited on the cathode. The anode residue was characterized by Xray diffraction, scanning electron microscopy, Raman spectrum and transmission electron microscopy.Results indicated that this type of porous carbon material with a high degree of graphitization has a multimodal pore system consisting of micropores, mesopores and macropores, which is hierarchical carbide derived carbon (CDC). The anode and cathode current efficiencies are estimated to be at least 92% and 80%, respectively. All results implied that it is feasible to prepare carbide derived carbon monoliths with a hierarchical pore structure and low carbon ferromanganese simultaneously by molten salt electrolysis.

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