Metal porphyrin intercalated reduced graphene oxide nanocomposite utilized for electrocatalytic oxygen reduction

In this paper, we report a simple and facile self-assembly method to successfully fabricate cationic metal porphyrin-MtTMPyP(Mt= Cobalt(Ⅱ), Manganese(Ⅲ), or Iron(Ⅲ); TMPyP = 5, 10, 15, 20-tetrakis(N-methylpyridinium-4-yl) porphyrin) intercalated into the layer of graphene oxide(GO) by the cooperative effects of electrostatic and π-π stacking interaction between positively charged metal porphyrin and negatively charged GO sheets. Followed by reduction with hydrazine vapor, a series of novel 2 D MtTMPyP/rGO_n were fabricated. The as-prepared 2 D hybrids were fully characterized and tested as non-noble metal catalysts for oxygen reduction reaction(ORR) in an alkaline medium. The MtTMPyP/rGO_n hybrids, especially CoTMPyP/rGO_5, demonstrated an improved electrocatalytic activity for ORR and a number of exchanged electrons close to 4-electron reaction, increased stability and excellent tolerance to methanol, showing a potential alternative catalyst for ORR in fuel cells and air batteries.

Synthesis of nitrogen-sulfur co-doped Ti_(3)C_(2)Tx MXene with enhanced electrochemical properties

Through material innovation,nanoscale structural design and hybrid manufacturing methods,great efforts have been made in developing high-performance energy storage systems.These devices can be comprised of twodimensional(2D)nanomaterials,such as MXene,and show promise for use in energy storage devices.In order to achieve better electrochemical properties of MXene,one crucial technique is to modify its structure by introducing defects or heteroatom dopants,which may expand the interlayer spacing and increase the ion transfer kinetics during the charge/discharge process.Here,a modified two-step multi-element strategy is explored utilizing ammonium citrate as intercalant and nitrogen source to enhance the level of heteroatom doping during annealing of MXene with sulfur.The resulting nitrogen/sulfur co-doped MXene displayed enhanced gravimetric capacitance(495 F g^(-1) at 1 A g^(-1)),outstanding rate capability(180 F g^(-1) at 10 A g^(-1))and excellent cycle stability(98%retention after 6000 charge/discharge cycles).The synthesis of NS-MXene reveals a novel and facile multiheteroatom pathway for functionalizing Ti_(3)C_(2)Tx MXene and demonstrates the potential variety of this family of modified MXenes that has yet to be explored,as well as unveils great promise for use in applications such as high performance supercapacitors.

Recent advances and opportunities in MXene-based liquid crystals

The recent progress on the liquid crystalline(LC)dispersion of two-dimensional(2D)transition metal carbides(MXenes)has propelled this unique nanomaterial into a realm of high-performance architectures,such as films and fibers.Additionally,compared to architectures made from typical non-LC dispersions,those derived from LC MXene possess tunable ion transport routes and enhanced conductivity and physical properties,demonstrating great potential for a wide range of applications,such as electronic displays,smart glasses,and thermal camouflage devices.This review provides an overview of the progress achieved in the production and processing of LC MXenes,including critical discussions on satisfying the required conditions for LC formation.It also highlights how acquiring LC MXenes has broadened the current solution-based manufacturing paradigm of MXene-based architectures,resulting in unprecedented performances in their conventional applications(e.g.,energy storage and strain sensing)and in their emerging uses(e.g.,tribology).Opportunities for innovation and foreseen challenges are also discussed,offering future research directions on how to further benefit from the exciting potential of LC MXenes with the aim of promoting their widespread use in designing and manufacturing advanced materials and applications.