Advances of Carbon Materials for Dual-Carbon Lithium-Ion Capacitors: A Review.

Lithium-ion capacitors (LICs) have drawn increasing attention, due to their appealing potential for bridging the performance gap between lithium-ion batteries and supercapacitors. Especially, dual-carbon lithium-ion capacitors (DC-LICs) are even more attractive because of the low cost, high conductivity, and tunable nanostructure/surface chemistry/composition, as well as excellent chemical/electrochemical stability of carbon materials. Based on the well-matched capacity and rate between the cathode and anode, DC-LICs show superior electrochemical performances over traditional LICs and are considered to be one of the most promising alternatives to the current energy storage devices. In particular, the mismatch between the cathode and anode could be further suppressed by applying carbon nanomaterials. Although great progresses of DC-LICs have been achieved, a comprehensive review about the advances of electrode materials is still absent. Herein, in this review, the progresses of traditional and nanosized carbons as cathode/anode materials for DC-LICs are systematically summarized, with an emphasis on their synthesis, structure, morphology, and electrochemical performances. Furthermore, an outlook is tentatively presented, aiming to develop advanced DC-LICs for commercial applications.

Soft magnetic Fe5C2-Fe3C@C as an electrocatalyst for the hydrogen evolution reaction.

Herein, cubic iron carbides encapsulated in an N-doped carbon shell (ICs@NC) were prepared by a simple two-step method. The two-step method included the preparation of iron oxalate dihydrate and the process of calcination with ethylenediamine. By changing the calcination temperature, we could control the type of iron carbide formed. Moreover, the prepared iron carbide@N-doped carbon core-shell particles exhibited regular cubic shapes and soft magnetic properties with high saturation magnetization. More importantly, we investigated the electrocatalytic activity of the iron carbide@N-doped carbon catalysts for the hydrogen evolution reaction (HER). The results show that the Fe5C2-Fe3C@NC catalyst has efficient HER catalytic activity with an overpotential of 209 mV@10 mA cm-2.

Low-temperature one-pot synthesis of WS2 nanoflakes as electrocatalyst for hydrogen evolution reaction.

Transition metal dichalcogenides have unique physicochemical properties. Herein, a low-temperature facile method is demonstrated to synthesize ultrathin tungsten disulfide nanoflakes. They are loosely stacked between layers with highly exposed edges, which provide lots of active sites for electrochemical applications. The by-product of crystalline carbon improves their conductivity, which also enhances their performance in hydrogen evolution reaction.

Iron Carbides and Nitrides: Ancient Materials with Novel Prospects.

Iron carbides and nitrides have aroused great interest in researchers, due to their excellent magnetic properties, good machinability and the particular catalytic activity. Based on these advantages, iron carbides and nitrides can be applied in various areas such as magnetic materials, biomedical, photo- and electrocatalysis. In contrast to their simple elemental composition, the synthesis of iron carbides and nitrides still has great challenges, particularly at the nanoscale, but it is usually beneficial to improve performance in corresponding applications. In this review, we introduce the investigations about iron carbides and nitrides, concerning their structure, synthesis strategy and various applications from magnetism to the catalysis. Furthermore, the future prospects are also discussed briefly.

Magnetic γ'-Fe4 N/Fe3 C, χ-Fe5 C2 , and θ-Fe3 C by a Simple Route for Application as Electrochemical Catalysts.

A new and simple method to fabricate magnetic Fe4 N/Fe3 C samples is reported. Meanwhile, pure phase iron carbides (θ-Fe3 C and χ-Fe5 C2 ) were obtained by controlling experimental conditions. The structures, magnetic properties, and morphology of the samples were investigated according to the generalized analysis of X-ray diffraction, X-ray photoelectron spectroscopy, as well as transmission electron microscopy and vibrating sample magnetometry. The magnetic properties measurement revealed the remarkable magnetic properties of the samples at 2 and 300 K. The application of the prepared samples as catalysts for oxygen evolution reaction was also investigated in alkaline solution. This simple and convenient route provides a new path to fabricate other metal nitrides and carbides.