Hexagonal-close-packed (hcp) MoRu3 with Pt-like hydrogen binding energy exhibits excellent electrochemical performance when used as a hydrogen evolution reaction (HER) catalyst.

Tungsten carbide (WC) is an alternative to the costly and resource-constrained Pt-based catalysts. Herein, a one-step facile and easily scalable approach is reported to synthesize ultrafine WC nanocrystals encapsulated in porous N-doped carbon nanospheres (NC) by simple self-polymerization, drying, and annealing. It is worth mentioning that this developed method has four novel features: (1) the synthesis process, without any hard template or hydrocarbon gas feeding, is, notably, very facile and efficient with low cost; (2) the carbon coating on WC nanocrystals not only restrains coarsening of particles but also creates strong coupling interactions between the nanocrystallines and the conductive carbonaceous matrix; (3) uniform grape-like WC@NC nanospheres with high specific surface area can be obtained in a large scale; and (4) single-phase WC can be achieved. As a result, WC@NC demonstrates remarkable hydrogen evolution reaction (HER) electrocatalytic performance with overpotentials of 127 and 141 mV at a current density of 10 mA cm–2 and Tafel slopes of 56.3 and 78.7 mV dec–1 in acid and alkaline media, respectively. Our density functional theory calculations manifest that the strong synergistic electronic effect between WC and its intimately bonded carbon shell vastly boosts the HER electrocatalytic activity. WC@NC catalysts as a cathode are further tested in a home-made electrolyzer with 0.78 A cm–2 achieved at a cell voltage of 2 V at 80 °C and operated stably at 200 mA cm–2 for more than 20 h.

Highly porous Co3O4/NiCo2O4 nanostructures were synthesized using zeolitic imidazolate framework-67 (ZIF-67) nanocrystals. The oxide composite structure was adjusted by modifying ZIF-67 crystallite size and the pore structure by the coordination modulation method. After forming the zeolite imidazolate framework-67 (ZIF-67)/Ni–Co layered double hydroxide intermediate composite through reaction with nickel nitrate, the intermediate composite was heated in air to result in Co3O4/NiCo2O4. Nitrogen adsorption was used for pore structure characterization of the template and resultant oxide composite. The maximum capacitance of nanostructured Co3O4/NiCo2O4 was 770 F g–1 at a discharge current density of 1 A g–1 with acceptable cycle stability, maintaining 70% of the initial capacitance after 10,000 charge–discharge cycles.

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Atomically-dispersed iron-nitrogen-carbon (Fe–N–C) catalysts have arisen as promising candidates for replacing the costly precious metal catalysts in fuel cells but still face some grand challenges, such as insufficient site density and durability. Herein, we report a self-assembly method in an aqueous solution to develop an atomically-dispersed iron catalyst with high oxygen reduction reaction (ORR) activity and stability in acidic electrolytes. As determined by high-resolution transmission electron microscopy (HR-TEM), X-ray absorption spectroscopy (XAS), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), this benign aqueous synthesis strategy facilitates the formation of homogeneous atomic nitrogen-coordinated iron sites embedded in a popcorn-like porous graphitic carbon matrix. These catalyst properties contribute to the improved ORR kinetic current density and mass transport. By controlling synthesis chemistry, the correlation between structure and property is systematically investigated. The iron content is the most critical material property and can regulate site density and graphitic carbon structures in the catalyst, impacting catalytic activity and stability. The enhanced performance and durability were examined in both acidic aqueous electrolytes and membrane electrode assemblies.