Optimized electron/ion transport by constructing radially oriented channels in MXene hybrid fiber electrodes for high-performance supercapacitors at low temperatures

Abstract

Although flexible fiber supercapacitors with two-dimensional active nanomaterials are promising for powering miniaturized wearable electronics, the difficulty of fiber electrodes to fully contact with electrolytes causes extremely tortuous ion pathways...

Adaptive and Adjustable MXene/Reduced Graphene Oxide Hybrid Aerogel Composites Integrated with Phase-Change Material and Thermochromic Coating for Synchronous Visible/Infrared Camouflages

“…The weak peak at ∼24° reflects the existence of the RGO component obtained by partially reducing GO sheets . Consistently, the Raman spectra (Figure c) present the A 1g symmetry out-of-plane vibrations of Ti atoms (194 cm –1 ) and C atoms (710 cm –1 ), and the E g group vibrations in-plane modes of Ti atoms (279 cm –1 ), C atoms (363 cm –1 ), and surface termination (624 cm –1 ), demonstrating the preserved intrinsic structure of the MXene. Similarly, the characteristic peaks of D (1333 cm –1 ) and G (1596 cm –1 ) bands derived from graphitic carbon also prove the presence of the RGO.…”

“…The emerging peak shifts are related to the van der Waals forces and hydrogen bonding between the MXene and the RGO . In addition, the typical peaks of the MXene and RGO components in their FTIR and XPS spectra (Figure S4) also indicate the combination of MXene and RGO. ,− The SEM images clearly display the sectional structure of the hybrid aerogel. As shown in Figures d,e and S5a, the MG hybrid aerogel exhibits a directional channel structure with a spacing of ∼20 μm due to the regular assembly and the orientated stacking of the MXene and p-RGO sheets during the unidirectional freezing process.…”

“…Thanks to their similar hydrophilicity and negative charge, , the MXene and graphene oxide (GO) sheets can be mixed homogeneously under ultrasonication . During the first prereduction with the VC reduction agent and hydrothermal assembly of the MXene/GO mixed suspension at 70 °C, the GO sheets (Figure S1a,b) are partially reduced and interconnected to construct a continuous three-dimensional framework, while the smaller MXene sheets (Figure S1c,d) are distributed on the partially reduced RGO (p-RGO) sheets by their intimate interfacial interactions (Figure S2a), forming an MXene/p-RGO hybrid hydrogel …”

“…39 During the first prereduction with the VC reduction agent and hydrothermal assembly of the MXene/GO mixed suspension at 70 °C, the GO sheets (Figure S1a,b) are partially reduced and interconnected to construct a continuous three-dimensional framework, 40 while the smaller MXene sheets (Figure S1c,d) are distributed on the partially reduced RGO (p-RGO) sheets by their intimate interfacial interactions (Figure S2a), forming an MXene/p-RGO hybrid hydrogel. 41 To construct unidirectional channels, the hybrid hydrogel is unidirectionally frozen by putting it on a copper cylinder whose bottom part is immersed in liquid nitrogen, during which numerous ice crystals are generated and grow vertically along with the temperature gradients, 42,43 thus the MXene and p-RGO sheets are expelled from the icicles and align vertically, forming an anisotropic MXene/p-RGO hybrid hydrogel. 44,45 The second reduction at 90 °C further removes the oxygencontaining groups of the p-RGO sheets, 46 which enhances the π−π conjugation interactions, 40 promoting the stability of the MXene/RGO hydrogel framework.…”

Recent advances in energy storage with graphene oxide for supercapacitor technology

“…Efforts are being made to enhance the ion transport properties by reducing the interlayer spacing and introducing additional pores or channels within the GO structure. [99][100][101] Furthermore, the stability of GO-based SCs needs to be addressed. GO is susceptible to chemical and electrochemical reactions that can degrade its performance over time.…”