The van der Waals heterostructures have evolved as novel materials for complementing the Si-based semiconductor technologies. Group-10 noble metal dichalcogenides (e.g., PtS₂, PtSe₂, PdS₂, and PdSe₂) have been listed into two-dimensional (2D) materials toolkit to assemble van der Waals heterostructures. Among them, PdSe₂ demonstrates advantages of high stability in air, high mobility, and wide tunable bandgap. However, the regulation of p-type doping of PdSe₂ remains unsolved problem prior to fabricating p–n junction as a fundamental platform of semiconductor physics. Besides, a quantitative method for the controllable doping of PdSe₂ is yet to be reported. In this study, the doping level of PdSe₂ was correlated with the concentration of Lewis acids, for example, SnCl₄, used for soaking. Considering the transfer characteristics, the threshold voltage (the gate voltage corresponding to the minimum drain current) increased after SnCl₄ soaking treatment. PdSe₂ transistors were soaked in SnCl₄ solutions with five different concentrations. The threshold voltages from the as-obtained transfer curves were extracted for linear fitting to the threshold voltage versus doping concentration correlation equation. This study provides in-depth insights into the controllable p-type doping of PdSe₂. It may also push forward the research of the regulation of conductivity behaviors of 2D materials.

Human beings perceive the world through the senses of sight, hearing, smell, taste, touch, space, and balance. The first five senses are prerequisites for people to live. The sensing organs upload information to the nervous systems, including the brain, for interpreting the surrounding environment. Then, the brain sends commands to muscles reflexively to react to stimuli, including light, gas, chemicals, sound, and pressure. MXene, as an emerging two-dimensional material, has been intensively adopted in the applications of various sensors and actuators. In this review, we update the sensors to mimic five primary senses and actuators for stimulating muscles, which employ MXene-based film, membrane, and composite with other functional materials. First, a brief introduction is delivered for the structure, properties, and synthesis methods of MXenes. Then, we feed the readers the recent reports on the MXene-derived image sensors as artificial retinas, gas sensors, chemical biosensors, acoustic devices, and tactile sensors for electronic skin. Besides, the actuators of MXene-based composite are introduced. Eventually, future opportunities are given to MXene research based on the requirements of artificial intelligence and humanoid robot, which may induce prospects in accompanying healthcare and biomedical engineering applications.

Graphene is a material with unique properties that can be exploited in electronics, catalysis, energy, and bio-related fields. Although, for maximal utilization of this material, high-quality graphene is required at both the growth process and after transfer of the graphene film to the application-compatible substrate. Chemical vapor deposition (CVD) is an important method for growing high-quality graphene on non-technological substrates (as, metal substrates, e.g., copper foil). Thus, there are also considerable efforts toward the efficient and non-damaging transfer of quality of graphene on to technologically relevant materials and systems. In this review article, a range of graphene current transfer techniques are reviewed from the standpoint of their impact on contamination control and structural integrity preservation of the as-produced graphene. In addition, their scalability, cost- and time-effectiveness are discussed. We summarize with a perspective on the transfer challenges, alternative options and future developments toward graphene technology.

In situ low-voltage aberration corrected transmission electron microscopy (TEM) observations of the dynamic entrapment of a C₆₀ molecule in the saddle of a bent double-walled carbon nanotube is presented. The fullerene interaction is non-covalent, suggesting that enhanced π–π interactions (van der Waals forces) are responsible. Classical molecular dynamics calculations confirm that the increased interaction area associated with a buckle is sufficient to trap a fullerene. Moreover, they show hopping behavior in agreement with our experimental observations. Our findings further our understanding of carbon nanostructure interactions, which are important in the rapidly developing field of low-voltage aberration corrected TEM and nano-carbon device fabrication.