MXenes are fast-growing two-dimensional (2D) carbides, nitrides, and carbonitrides nanomaterials exhibiting combined special features of high electronic conductivity, optoelectronic properties, and electrochemical properties with hydrophilicity character. The plasmonic characteristics of MXenes with optical nonlinearities associated with ultrafast dynamics empower it as one of the strongest candidates for transparent optoelectronic applications in the field of energy storage, conversion, photodetectors, quantum dot light-emitting diodes, smart windows, environmentally. It is timely to introduce and summarize a review article dedicated to the transparent MXene-based multifunctional applications that provide well-designed future roadmaps for these significant MXene smart materials. This review comprehensively discusses the transparent MXenes towards transparent electrodes for supercapacitors and beyond. The importance of MXene optoelectronic properties and tunability via composite materials incorporated with different polymers, oxides, sulfides, and carbonaceous nanomaterials are also thoroughly reviewed.

The effect of twist angle on the hydrogenation of bilayer graphene (BLG) is systematically explored by density functional theory (DFT) calculations. We found that a twist between the upper and lower layers of the graphene BLGs, either big or small, interferes with the formation of inter-layer C–C covalent bonds and this leads to strong resistance to hydrogenation. In addition, the electronic properties of stable, hydrogenated twisted BLG with different twist angles and degrees of H coverage were investigated. This study paves the way to the selective functionalization of BLG for various applications.