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Hydrogen is considered a key renewable energy source to meet future energy needs, and the accelerated development of hydrogen energy is largely dependent on the cost-effective and efficient production of hydrogen. Nowadays, the production of hydrogen by electrolyzing water is a generation of clean energy with great potential for development, but its industrialization requires the search for cheap and efficient catalysts. Platinum (Pt) is currently regarded as the most effective catalyst for the production of hydrogen from electrolytic water. However, its high price and scarcity limit its scale up, so the search for cheap and efficient catalysts has become a hot research topic. Nowadays, various noble/non-precious and metal-free catalysts have been developed for hydrogen evolution processes, among which ruthenium (Ru) catalysts are recognized as a promising material for hydrogen production from electrolytic water because they make a better balance between performance and price. In this review, we summarized the reported ruthenium-based catalysts with excellent hydrogen evolution reaction (HER) activity, specifically, Ru with carbon supports, Ru phosphide–based catalysts, and Ru catalysts on other metals. Finally, we discussed challenges and prospects for the development of Ru-based catalysts in the field of HER research. [ABSTRACT FROM AUTHOR]

LiBF4 has attracted much attention due to its better thermal stability, lower sensitivity to environmental humidity, and lower charge transfer resistance provided by its solution, especially at high voltage. Herein, the effects of the concentration of LiBF4 salt on the stability and electrochemical properties of LiNi0.5Mn1.5O4 (LNMO) cathode material have been investigated by using the mixed solvents of LiBF4 salt, vinyl carbonate (EC), and diethyl carbonate (DEC) as electrolytes. The surface morphology and structure of cycled LNMO electrode are studied by scanning electron microscopy (SEM), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The results show that the optimum concentration of LiBF4 salt is 1.4 M LiBF4-EC/DEC (1:5, by volume). Under optimum conditions, the LNMO cathode material has high electrochemical capacity and favorable rate performance. Meanwhile, the prepared electrolyte can easily form a thin and stable SEI film on the surface of LNMO electrode, which can effectively inhibit the continuous decomposition of the electrolyte. [ABSTRACT FROM AUTHOR]

In order to improve the universality of LiMn2O4 materials, LiMn2O4 coated with Al2O3 (LMO@Al) is prepared by a co-precipitated method to improve the electrochemical performance of the porous LiMn2O4 cathode. The morphologies and microstructures are characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, and energy-dispersive spectroscopy. The electrochemical performances are investigated by galvanostatic charge-discharge test system and inductively coupled plasma emission spectrograph. The results show that the Al2O3 coating uniformly as well as tightly coupled with LiMn2O4 particles. The LMO@Al cathode material also shows outstanding electrochemical behaviors. After 100 cycles, the capacitance can remain 98.6 and 91.2% at 25 and 55 °C, respectively. Moreover, the LMO@Al composite cycled reversibly at 25 °C for 10 C with stable discharge capacities of 94.4 mAh g−1. Superior electrochemical stability of the LMO@Al can be attributed to the uniform coating which inhibited the manganese dissolution and Jahn-Teller effect of LiMn2O4 materials as well as the decomposition of the electrode by HF corrosion. The LMO@Al obtained from this work can open a new possibility in high power lithium ion batteries application. [ABSTRACT FROM AUTHOR]

Iron nanoparticles wrapped in N-doped carbon (INC) were synthesized by a two-step method which includes a hydrothermal and a thermal treatment. The PtSn nanoparticles were then deposited on the resulting carbon material using an ethylene glycol reduction method. Scanning electron microscopy images indicated INC had an interconnected, porous framework with continuous macropores in the micrometer range. Transmission electronic microscopy and X-ray diffraction results proved that the iron nanoparticles were completely wrapped in the N-doped carbon. Cyclic voltammograms for ethanol oxidation showed that the mass activity on PtSn/INC electrode reaches 424.5 mA mg, 1.64 times as large as that for PtSn/C (259.0 mA mg). PtSn/INC also exhibited better durability in ethanol oxidation reaction than PtSn/C. These results indicated that INC is a potential high-performance catalyst support material for fuel cell catalysts. [ABSTRACT FROM AUTHOR]