3D hierarchical Ti3C2/TiO2 composite via in situ oxidation for improved lithium-ion storage

To address the intrinsic limitations of both TiO2 and MXenes, we propose an effective strategy for the engineering of a 3D Ti3C2/TiO2 nanorod hybrid, where the in situ synthesized TiO2 nanorods are homogeneously decorated onto the surface of 3D Ti3C2 MXene via simple oxidation. As the LIB anode, it demonstrates exceptional long-term cycling stability with a specific capacity of 384.1 mA h g-1 after 600 cycles at 1.0 A g-1.

MXene/graphene oxide heterojunction as a high performance anode material for lithium ion batteries

MXene/graphene oxide composites with strong interfacial interactions were constructed by ball milling in vacuum. Graphene oxide (GO) acted as a bridge between Ti3C2Tx nanosheets in the composite material, which could buffer the mechanical shear force during the ball milling process, avoid the structural damage of nanosheets and improve the structural stability of the composite material during the lithium process. Partial oxidation of Ti3C2Tx nanosheets is caused by high temperatures during ball milling, which is beneficial to improve the intercalation of lithium ions in the material, reduce the stress and electrostatic repulsion between adjacent layers, and cause the composite to have better lithium storage performance. Under the high current density of 2.5 A g-1, the reversible capacity of the Ti3C2Tx/GO composite material after 2000 cycles was 116.5 mA h g-1, and the capacity retention was as high as 116.6%.

Recent progress in use of MXene in perovskite solar cells: for interfacial modification, work-function tuning and additive engineering

The use of perovskites in photovoltaic and related industries has achieved tremendous success over the last decade. However, there are still obstacles to overcome in terms of boosting their performance and resolving stability issues for future commercialization. The introduction of a new 2D material of halide perovskites is now the key advancement in boosting the solar energy conversion efficiency. The implication of a new 2D material (MXene) in perovskite solar cells has been initiated since its first report in 2018, showing excellent transparency, electrical conductivity, carrier mobility, superior mechanical strength, and tunable work function. Based on distinctive features at the hetero-interface, halide perovskite and MXene heterostructures (HPs/Mx) have recently exhibited exceptional improvements in both the performance and stability of perovskite solar cells. Furthermore, the wide families of HPs and MXene materials allow playing with the composition and functionalities of HP/Mx interfaces by applying rational designing and alterations. In this review a comprehensive study of implementing MXenes in perovskite solar cells is presented. First, the implementation of MXenes in perovskites as an additive, and then in charge extraction layers (HTL/ETL), is described in detail. It is worth noting that still only Ti₃C₂T_x, Nb₂CT_x,V₂CT_x MXene is being incorporated into perovskite photovoltaics. Finally, the present obstacles in the use of MXenes in PSCS are discussed, along with the future research potential. This review is expected to provide a complete and in-depth description of the current state of research and to open up new opportunities for the study of other MXenes in PSCs.

A Brief Review of the Role of 2D Mxene Nanosheets toward Solar Cells Efficiency Improvement

This article discusses the application of two-dimensional metal MXenes in solar cells (SCs), which has attracted a lot of interest due to their outstanding transparency, metallic electrical conductivity, and mechanical characteristics. In addition, some application examples of MXenes as an electrode, additive, and electron/hole transport layer in perovskite solar cells are described individually, with essential research issues highlighted. Firstly, it is imperative to comprehend the conversion efficiency of solar cells and the difficulties of effectively incorporating metal MXenes into the building blocks of solar cells to improve stability and operational performance. Based on the analysis of new articles, several ideas have been generated to advance the exploration of the potential of MXene in SCs. In addition, research into other relevant MXene suitable in perovskite solar cells (PSCs) is required to enhance the relevant work. Therefore, we identify new perspectives to achieve solar cell power conversion efficiency with an excellent quality-cost ratio.

MXene derivatives: synthesis and applications in energy convention and storage

Transition metal carbides or nitrides (MXene) have shown promising applications in energy convention and storage (ECS), owing to their high conductivity and adjustable surface functional groups. In the past several years, many MXene derivatives with different structures have been successfully prepared and their impressive performance demonstrated in ECS. This review summarizes the progress in the synthesis of MXene and typical Ti3C2T x MXene derivatives with different morphologies, including 0D quantum dots, 1D nanoribbons, 2D nanosheets and 3D nanoflowers. The mechanisms involved and their performance in photocatalysis, electrocatalysis and rechargeable batteries are also discussed. Furthermore, the challenges of MXene derivatives in ECS are also proposed.

MXenes for Solar Cells

Application of two-dimensional MXene materials in photovoltaics has attracted increasing attention since the first report in 2018 due to their metallic electrical conductivity, high carrier mobility, excellent transparency, tunable work function and superior mechanical property. In this review, all developments and applications of the Ti₃C₂T_x MXene (here, it is noteworthy that there are still no reports on other MXenes' application in photovoltaics by far) as additive, electrode and hole/electron transport layer in solar cells are detailedly summarized, and meanwhile, the problems existing in the related studies are also discussed. In view of these problems, some suggestions are given for pushing exploration of the MXenes' application in solar cells. It is believed that this review can provide a comprehensive and deep understanding into the research status and, moreover, helps widen a new situation for the study of MXenes in photovoltaics.