Extensive research on two-dimensional (2D) materials has triggered the renaissance of an old topic, that is, the intercalation and exfoliation of layer materials. Such top-down exfoliation produced 2D materials and their dispersions have several advantages including low cost, scalable production capability, solution processability, and versatile functionalities stemming from the large number of species of layer materials, and show promising potential in many applications. In recent years, many new methods have been developed for exfoliating layer materials to 2D materials for different application purposes. In this review the different exfoliation approaches are first systematically analyzed from the viewpoint of methodology, and the advantages and disadvantages of each method are compared. Second, the assembly of exfoliated 2D materials into macrostructures by solution-based techniques is summarized. Third, the state-of-the-art applications of 2D material dispersions and their assemblies in electronics and optoelectronics, electrocatalysis, energy storage, etc., are discussed. Finally, insights and perspectives on current research challenges and future opportunities regarding the exfoliation and applications of 2D materials in dispersions are considered.

Titanium carbide MXene quantum dots (QDs) were synthesized using an effective fluorine-free method as a biocompatible and highly efficient nanoagent for photothermal therapy (PTT) applications. In contrast to the traditional, hazardous and time-consuming process of HF pretreatment, our fluorine-free method is safe and simple. More importantly, abundant Al oxoanions were found to be modified on the MXene QD surface by the fluorine-free method, which endowed the QDs with strong and broad absorption in the NIR region. As a result, the as-prepared MXene QDs exhibited an extinction coefficient as large as 52.8 Lg⁻¹ cm⁻¹ at 808 nm and a photothermal conversion efficiency as high as 52.2%. Both the values are among the best reported so far. The as-prepared MXene QDs achieved simultaneous photoacoustic (PA) imaging and the remarkable PTT effect of tumors. Moreover, MXene QDs showed great biocompatibility without causing noticeable toxicity in vitro and in vivo, indicating their high potential for clinical applications.

The microscopic reaction pathway plays a crucial role in determining the electrochemical performance. However, artificially manipulating the reaction pathway still faces considerable challenges. In this study, we focus on the classical acidic water oxidation based on RuO₂ catalysts, which currently face the issues of low activity and poor stability. As a proof-of-concept, we propose a strategy to create local structural symmetry but oxidation-state asymmetric Mn^4-δ-O-Ru^4+δ active sites by introducing Mn atoms into RuO₂ host, thereby switching the reaction pathway from traditional adsorbate evolution mechanism to oxide path mechanism. Through advanced operando synchrotron spectroscopies and density functional theory calculations, we demonstrate the synergistic effect of dual-active metal sites in asymmetric Mn^4-δ-O-Ru^4+δ microstructure in optimizing the adsorption energy and rate-determining step barrier via an oxide path mechanism. This study highlights the importance of engineering reaction pathways and provides an alternative strategy for promoting acidic water oxidation.