Low-dimensional nanomaterials, owing to their unique and versatile properties, are very attractive for enormous electronic and optoelectronic applications. PbS quantum dots (QDs), characterized by a large Bohr radius and size-tunable bandgap, are especially interesting for photonic applications in the near-infrared region. Here, oleic acid capped colloidal PbS QDs as a saturable absorber are investigated for ultrashort-pulse generation. The PbS QDs exhibit outstanding nonlinear saturable absorption properties at 1550 nm: a modulation depth up to 44.5% and a thermal damage threshold larger than $30\mathrm{mJ}/{\mathrm{cm}}^2$. By incorporating PbS QDs into a fiber laser, a transform-limited soliton pulse as short as 559 fs with a bandwidth of 4.78 nm is realized at 1563 nm. Numerous applications may benefit from the nonlinear saturable absorption properties of PbS QDs, such as near-infrared pulsed lasers and modulators.

Low electrical conductivity severely limits the application of Fe₂O₃ in lithium- and sodium-ion batteries. In respect of this, we design and fabricate Fe₂O₃/Fe₃O₄ nano-aggregates anchored on nitrogen-doped graphene as an anode for sodium-ion batteries with the assistance of microwave plasma. The highly conductive Fe₃O₄ in the composite can function as a highway of electron transport, and the voids and phase boundaries in the Fe₂O₃/Fe₃O₄ heterostructure facilitate Na⁺ ion diffusion into the nano-aggregates. Furthermore, the Fe–O–C bonds between the nano-aggregates and graphene not only stabilize the structural integrity, but also enhance the charge transfer. Consequently, the Fe₂O₃/Fe₃O₄/NG anode exhibits specific capacity up to 362 mAh g⁻¹ at 100 mA g⁻¹, excellent rate capability, and stable long-term cycling performance. This multi-component-based heterostructure design can be used in anode materials for lithium- and sodium-ion batteries, and potential opens a new path for energy storage electrodes.

Superelastic graphene aerogel with ultra-high compressibility shows promising potential for compression-tolerant supercapacitor electrode. However, its specific capacitance is too low to meet the practical application. Herein, we deposited polyaniline (PANI) into the superelastic graphene aerogel to improve the capacitance while maintaining the superelasticity. Graphene/PANI aerogel with optimized PANI mass content of 63 wt% shows the improved specific capacitance of 713 F g−1 in the three-electrode system. And the graphene/PANI aerogel presents a high recoverable compressive strain of 90% due to the strong interaction between PANI and graphene. The all-solid-state supercapacitors were assembled to demonstrate the compression-tolerant ability of graphene/PANI electrodes. The gravimetric capacitance of graphene/PANI electrodes reaches 424 F g−1 and retains 96% even at 90% compressive strain. And a volumetric capacitance of 65.5 F cm−3 is achieved, which is much higher than that of other compressible composite electrodes. Furthermore, several compressible supercapacitors can be integrated and connected in series to enhance the overall output voltage, suggesting the potential to meet the practical application.