The superior properties of nanomaterials with a special structure can provide prospects for highly efficient water splitting and lithium storage. Herein, we fabricated a series of peapodlike C@Ni_2−xCo_xP (x≤1) nanocomposites by an anion-exchange pathway. The experimental results indicated that the HER activity of C@Ni_2−xCo_xP catalyst is strongly related to the Co/Ni ratio, and the C@NiCoP got the highest HER activity with low onset potential of ∼45 mV, small Tafel slope of ∼43 mV dec⁻¹, large exchange current density of 0.21 mA cm⁻², and high long-term durability (60 h) in 0.5 m H₂SO₄ solutions. Equally importantly, as an anode electrode for lithium batteries, this peapodlike C@NiCoP nanocomposite gives excellent charge–discharge properties (e.g., specific capacity of 670 mAh g⁻¹ at 0.2 A g⁻¹ after 350 cycles, and a reversible capacity of 405 mAh g⁻¹ at a high current rate of 10 A g⁻¹). The outstanding performance of C@NiCoP in HER and LIBs could be attributed to the synergistic effect of the rational design of peapodlike nanostructures and the introduction of Co element.

In this article, the two-layer sandwiched graphene@LiFe_0.2Co_0.8O₂ nanoparticles (SG@LFCO) have been prepared and investigated as high-rate and long-life cathode materials for rechargeable lithium-ion batteries. The materials possess a high-surface area (267.1 m² g⁻¹) and lots of void spaces. By combining various favorable conditions, such as Fe doping, coating graphene, and designing novel morphology, the as-prepared materials deliver a specific capacity of 115 mAh g⁻¹ at 10 C. At the 0.1 C cycling rate, the capacity retention of 97.2 % is sustained after 250 cycles and a coulombic efficiency of around 97.6 % is obtained.

Herein, a peapod-like TiO₂/carbon nanocomposite has successfully been synthesized by a rational method for the first time. The novel nanostructure exhibits a distinct feature of TiO₂ nanoparticles encapsulated inside and the carbon fiber coating outside. In the synthetic process, H₂Ti₃O₇ nanotubes serve as precursors and templates, and glucose molecules act as the green carbon source. With the alliciency of hydrogen bonding between H₂Ti₃O₇ and glucose, a thin polymer layer is hydrothermally assembled and subsequently converted into carbon fibers through calcinations under an inert atmosphere. Meanwhile, the precursors of H₂Ti₃O₇ nanotubes are transformed into the TiO₂ nanoparticles encapsulated in carbon fibers. The achieved unique nanocomposites can be used as excellent anode materials in lithium-ion batteries (LIBs) and photocatalytic reagents in the degradation of rhodamine B. Due to the synergistic effect derived from TiO₂ nanoparticles and carbon fibers, the obtained peapod-like TiO₂/carbon cannot only deliver a high specific capacity of 160 mAh g⁻¹ over 500 cycles in LIBs, but also perform a much faster photodegradation rate than bare TiO₂ and P25. Furthermore, owing to the low cost, environmental friendliness as well as abundant source, this novel TiO₂/carbon nanocomposite will have a great potential to be extended to other application fields, such as specific catalysis, gas sensing, and photovoltaics.

Herein, we introduce a peapod-like composite with Ni₁₂P₅ nanoparticles encapsulated in carbon fibers as the enhanced anode in Li-ion batteries for the first time. In the synthesis, NiNH₄PO₄⋅H₂O nanorods act as precursors and sacrificial templates, and glucose molecules serve as the green carbon source. With the aid of hydrogen bonding between the precursor and carbon source, a polymer layer is hydrothermally formed and then rationally converted into carbon fibers upon inert calcination at elevated temperatures. Meanwhile, NiNH₄PO₄⋅H₂O nanorods simultaneously turn into Ni₁₂P₅ nanoparticles encapsulated in carbon fibers by undergoing a decomposition and reduction process induced by high temperature and the carbon fibers. The obtained composite performs excellently as a Li-ion batteries anode relative to pure-phase materials. Specific capacity can reach 600 mAh g⁻¹ over 200 cycles, which is much higher than that of isolated graphitized carbon or phosphides, and reasonably believed to originate from the synergistic effect based on the combination of Ni₁₂P₅ nanoparticles and carbon fibers. Due to the benignity, sustainability, low cost, and abundance of raw materials of the peapod-like composite, numerous potential applications, in fields such as optoelectronics, electronics, specific catalysis, gas sensing, and biotechnology can be envisaged.

A novel and universal approach towards the unique encapsulation of nanoparticles in the sandwiched graphene sheets is presented here. In the method, a low-cost, sustainable and environmentally friendly carbon source, glucose, is firstly applied to yield the high-quality, uniform and coupled graphene sheets in a large scale, and the pre-fabricated hydrated nanosheets act as the sacrificial templates to generate the enveloped metallic nanoparticles. After controllable oxidation or removal of the encapsulated nanoparticles, sandwiched nanocomposite with oxidizes nanoparticles encapsulated in graphene sheets or pure phase of sandwich-like and coupled graphene sheets would be achieved. Moreover, the synergic effect on energy storage via Li-ion batteries is solidly verified in the Co₃O₄@graphene nanocomposite. More importantly, the unique structure of the nanoparticles-encapsulated sandwiched graphene sheets will definitely result in additional applications, such as biosensors, supercapacitors and specific catalyses. These results have enriched the family of graphene-based materials and recognized some new graphene derivatives, which will be considerably meaningful in chemistry and materials sciences.