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.

Vapor deposition and three-dimensional (3D) printing technology are considered to be conventional methods to achieve patterned metal film preparation through the assistance of masks and high temperature. Therefore, there are still some challenges in fabricating metal films in template-free and normal temperature environment. In this work, we report a flexible and rapid laser metal transfer (LMT) technique for fabricating the various metal films (Cu, Ni, Sn, Al, Fe, and Ag) with different patterns without templates on arbitrary substrates (glass, polyimide (PI) films, and aluminum nitride (AlN) ceramic). Especially, the obtained transparent conductive glass displays high transmittance (more than 90%) and adjustable resistances (≈ 5 Ω). According to the Joule effect, the interface resistance between Cu particles and copper oxide coating produces the high temperature approximately 280 °C at 2 V in a short time (≈ 60 s) and remains stable at 120 °C over 12 h. At last, the multifunctional glass with Cu patterns also shows excellent bactericidal activity (≈ 95%). This work demonstrates that laser metal transfer is an exceeding effective means of fabricating the micro/nano structures with potential applications in functional devices.

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.

Transition metal nitride/carbide (TMN/C) have been actively explored as low-cost hydrogen evolution reaction (HER) electrocatalysts owing to their Pt-like physical and chemical properties. Unfortunately, pure TMN/C suffers from strong hydrogen adsorption and lacks active centers for water dissociation. Herein, we developed a switchable WO₃-based in situ gas–solid reaction for preparing sophisticated Fe-N doped WC and Fe-C doped WN nanoarrays. Interestingly, the switch of codoping and phase can be effectively manipulated by regulating the amount of ferrocene. Resultant Fe-C-WN and Fe-N-WC exhibit robust electrocatalytic performance for HER in alkaline and acid electrolytes, respectively. The collective collaboration of morphological, phase and electronic effects are suggested to be responsible for the superior HER activity. The smallest |ΔG_H*| value of Fe-N-WC indicates preferable hydrogen-evolving kinetics on the Fe-N-WC surface for HER under acid condition, while Fe-C-WN is suggested to be beneficial to the adsorption and dissociation of H₂O for HER in alkaline electrolyte.

Carbon nanotubes (CNTs) have attracted great attentions in the field of electronics, sensors, healthcare, and energy conversion. Such emerging applications have driven the carbon nanotube research in a rapid fashion. Indeed, the structure control over CNTs has inspired an intensive research vortex due to the high promises in electronic and optical device applications. Here, this in-depth review is anticipated to provide insights into the controllable synthesis and applications of high-quality CNTs. First, the general synthesis and post-purification of CNTs are briefly discussed. Then, the state-of-the-art electronic device applications are discussed, including field-effect transistors, gas sensors, DNA biosensors, and pressure gauges. Besides, the optical sensors are delivered based on the photoluminescence. In addition, energy applications of CNTs are discussed such as thermoelectric energy generators. Eventually, future opportunities are proposed for the Internet of Things (IoT) oriented sensors, data processing, and artificial intelligence.

Spatial resolution is an important criterion to evaluate the performance of a scintillation screen for X-ray imaging. Perovskite-based X-ray screen, usually made of powders or polycrystalline films, suffers from low spatial resolution (~ 200 μm) due to the large thickness of scintillation layer despite of their compelling sensitivity to X-ray dose. In this work, a concentrated colloid of CsPbBr₃ nanosheets was synthesized via a co-precipitation method at ambient condition. By drop casting, smooth scintillation screens of varied thickness were formed through self-assembly, which exhibited both high internal and external photoluminescence quantum yield (PL QY) (84.5% and 75.1%, respectively). The screen-based X-ray detector showed a high sensitivity down to 27 nGy/s, two orders of magnitude lower than the regular dose for medical diagnostics. Importantly, the screen of optimal thickness of 15 μm showcased an unprecedented spatial resolution (26 μm) when used for X-ray radiography, representing one order of magnitude improvement in perovskite community.

Osteoimmunomodulation was identified as a new and important strategy to enhance osteogenic differentiation together with other osteogenic approaches. However, approaches regulating osteogenic differentiation and macrophage polarization to remodel an osteoinductive microenvironment are separate and complicated. Therefore, the design and synthesis of one biomaterial that couples the osteogenic performance and immunomodulatory ability is a major challenge for efficient bone repair. In this study, self-assembled iron–catechin nanoparticles (Fe–cat NPs) were designed based on the coordinated reaction between iron ions and catechin and synthesized via a facile one-pot strategy. Interestingly, Fe–cat NPs show intracellular pH-responsive disassembly and release catechin molecules under the low pH of lysosomes after endocytosis. This strategy delivers catechin intracellularly and then enhances the osteogenic differentiation while inhibits the adipogenic differentiation of human adipose-derived stem cells (hADSCs). More importantly, Fe–cat NPs remodel the osteogenic immune microenvironment by resisting inflammation and promoting M2 polarization of macrophages. As a promising metal–organic nanodrug, the intracellular pH-responsive Fe–cat NPs significantly enhance the therapeutic effect of bone regneration by orchestrating osteogenic differentiation and immunomodulation, which may have great potential in bone tissue engineering.

Electrocatalytic hydrogen production in alkaline media is extensively adopted in industry. Unfortunately, further performance improvement is severely impeded by the retarded kinetics, which requires the fine regulation of water dissociation, hydrogen recombination, and hydroxyl desorption. Herein, we develop a multi-interface engineering strategy to make an elaborate balance for the alkaline hydrogen evolution reaction (HER) kinetics. The graphene cross-linked three-phase nickel sulfide (NiS-NiS₂-Ni₃S₄) polymorph foam (G-NNNF) was constructed through hydrothermal sulfidation of graphene wrapped nickel foam as a three-dimensional (3D) scaffold template. The G-NNNF exhibits superior catalytic activity toward HER in alkaline electrolyte, which only requires an overpotential of 68 mV to drive 10 mA·cm⁻² and is better than most of the recently reported metal sulfides catalysts. Density functional theory (DFT) calculations verify the interfaces between nickel sulfides (NiS/NiS₂/Ni₃S₄) and cross-linked graphene can endow the electrocatalyst with preferable hydrogen adsorption as well as metallic nature. In addition, the electron transfer from Ni₃S₄/NiS₂ to NiS results in the electron accumulation on NiS and the hole accumulation on Ni₃S₄/NiS₂, respectively. The electron accumulation on NiS favors the optimization of the H* adsorption, whereas the hole accumulation on Ni₃S₄ is beneficial for the adsorption of H₂O. The work about multi-interface collaboration pushes forward the frontier of excellent polymorph catalysts design.

Nanomaterials show promising opportunities to address clinical problems (such as insufficient capture of circulating tumor cells; CTCs) via the high surface area-to-volume ratio and high affinity for biological cells. However, how to apply these nanomaterials as a nano-bio interface in a microfluidic device for efficient CTC capture with high specificity remains a challenge. In the present work, we first found that a titanium dioxide (TiO₂) nanorod array that can be conveniently prepared on multiple kinds of substrates has high affinity for tumor cells. Then, the TiO₂ nanorod array was vertically grown on the surface of a microchannel with hexagonally patterned Si micropillars via a hydrothermal reaction, forming a new kind of a micro-nano 3D hierarchically structured microfluidic device. The vertically grown TiO₂ nanorod array was used as a sensitive nano-bio interface of this 3D hierarchically structured microfluidic device, which showed high efficiency of CTC capture (76.7% ± 7.1%) in an artificial whole-blood sample.