The development of hydrogen evolution catalysts based on nonprecious metals is essential for the practical application of water-splitting devices. Herein, the synthesis of Co S -MoS hierarchical nanoboxes (HNBs) as efficient catalysts for the hydrogen evolution reaction (HER) is reported. The surface of the hollow cubic structure was organized by CoMoS nanosheets formed through the reaction of MoS and Co released from the cobalt zeolite imidazole framework (ZIF-67) templates under reflux in a mixture of water/ethanol. The formation process for the CoMoS HNB structures was characterized by TEM images recorded at various reaction temperatures. The amorphous CoMoS HNBs were converted through sequential heat treatments into CoS -MoS and Co S -MoS HNBs. Owing to their unique chemical compositions and structural features, Co S -MoS HNBs have a high specific surface area (124.6 m g ) and superior electrocatalytic performances for the HER. The Co S -MoS HNBs exhibit a low overpotential (η ) of 106 mV, a low Tafel slope of 51.8 mV dec , and long-term stability in an acidic medium. The electrocatalytic activity of Co S -MoS HNBs is superior to that of recently reported values, and these HNBs prove to be promising candidates for the HER.

Cobalt ditelluride nanocrystallites (average size ∼3–6 nm) embedded in robust carbon polyhedra (polyhedral CoTe2–C) were synthesized by a simple two-step sequential annealing process using a zeolitic imidazolate framework (ZIF-67), and their electrochemical behavior in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) was studied. The mechanism of structural phase changes in the polyhedral CoTe2–C was thoroughly investigated by various ex situ analysis tools. During Li- and Na-insertion/extraction, the CoTe2 nanocrystallites in the polyhedral C involved a conversion/recombination reaction. Because of the homogeneous embedding of CoTe2 nanocrystallites in a robust polyhedral carbon matrix and the electrochemical recombination reaction of CoTe2, agglomeration of CoTe2 nanocrystallites was prevented and volume strain during cycling was alleviated, which contributed to excellent electrochemical performance. The polyhedral CoTe2–C exhibited excellent electrochemical performance for Li- and Na-ion storage, including large reversible capacities (the initial reversible capacity: 500 mA h g–1 for LIBs and 323 mA h g–1 for SIBs), stable capacity retentions over 200 cycles, and fast C-rate behavior (386 mA h g–1 for LIBs at 3 C and 240 mA h g–1 for SIBs at 2 C rates, respectively) with excellent cyclic stability at a high 1 C rate (∼480 mA h g–1 for LIBs over 200 cycles and ∼250 mA h g–1 for SIBs over 200 cycles), which suggests that polyhedral CoTe2–C is highly suitable as a potential anode material for both LIBs and SIBs. This work provides a distinct architecture for a composite material that will be highly applicable for high-performance LIB and SIB anodes.

Highly efficient, nonprecious and stable electrocatalysts for the hydrogen evolution reaction (HER) are absolutely crucial for renewable energy conversion, yet the design of such catalysts remains to be a long and arduous task. Herein, cobalt phosphide (CoP) nanoparticles (NPs) embedded in hierarchical N‐doped carbon nanotube frameworks (CoP‐HNCs) have been synthesized by controlled phosphidation of cobalt NPs embedded in hierarchical N‐doped carbon nanotube frameworks (Co‐HNCs). The Co‐HNCs were prepared by direct carbonization of Co‐based zeolitic imidazolate networks (ZIF‐67). Benefitting from multiple structural and compositional features, such as a multitude of catalytically active sites, a high degree of graphitization, and a thin carbon layer enclosing the NPs, CoP‐HNCs serve as a superior electrocatalyst towards the hydrogen evolution reaction. The synthesized CoP‐HNCs delivered a low overpotential at a current density of 10 mA cm−2 (η10) of 79 mV and 96 mV with small Tafel slope value of 45.6 mV dec−1 and 49.5 mV dec−1 in acidic and alkaline conditions, respectively. In addition, the catalyst showed long‐time durability under both acidic and alkaline electrolyte conditions, further demonstrating their potential to replace Pt‐based precious catalysts.

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Development of an efficient electrocatalyst is an important requirement for water splitting systems to produce clean and sustainable hydrogen fuel. Herein, we synthesized CoP2/Fe-CoP2 yolk-shell nanoboxes (YSBs) as efficient electrocatalysts...

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