This study confirms the existence of several nanometer-ordered structures in amorphous Al2O3–2SiO2–Na2O–7H2O geopolymers by high-resolution transmission electron microscopy and selected area electron diffraction. The composition ratio of the geopolymers was designed according to the NaA zeolite composition (Si/Al/Na atom ratio of 1:1:1), and the expected NaA molecular sieve was achieved by the Al2O3–2SiO2–Na2O–7H2O geopolymers through a hydrothermal reaction. This design concept was used to convert geopolymers into zeolite molecular sieves and provides a new preparation method for zeolite membranes or zeolite bulk materials.

Co3O4-based spinels are a new class of wide-band-gap p-type conductive oxides with high work functions. We examined the structures, conductivities, work functions, and optical spectra of quaternary Zn–Ni–Co–O thin films across the entire spinel region of the ZnO–NiO–Co3O4 diagram using a high-throughput combinatorial approach. We found that the conductivity of as-deposited films is maximized (100 S/cm) and optical absorption (at 1.8 eV) is minimized in different regions of the diagram, while the work function of annealed films is high and relatively constant (5.8 ± 0.1 eV). These properties made Zn–Ni–Co–O thin films applicable as p-type interlayers in solar cells. As an example, amorphous Zn–Co–O hole transport layers had good performance in bulk heterojunction organic photovoltaic devices.

Multiwall carbon nanotubes (MWCNTs) are utilized to resolve low coupling coefficient issue by dispersing MWCNTs in poly(vinylidene fluoride) matrix to create stress reinforcing network, dispersant, and electron conducting functions for barium titanate (BT) nanoparticles. Various BT and MWCNT percentages of nanocomposite film are fabricated by FDM three-dimensional (3D) printing which can simplify the fabrication process as well as lower cost and design flexibility. Increasing MWCNTs and BT particles gradually increase piezoelectric coefficient (d 31) by 0.13 pC/N with 0.4 wt%-MWCNTs/18 wt%-BT. These results provide not only a technique to print piezoelectric nanocomposites but also unique materials combination for sensor application.

Beyond the traditional phase conversion or biphase mixing hybrid, we developed the dilute magnesium-doped wollastonite inks and three-dimensional (3D) printing approaches to fabricate the ultrahigh strength bioceramic porous scaffolds. The mechanical strength (>120 MPa) of the porous bioceramics was an order of magnitude higher than the pure wollastonite and other stoichiometric Ca–Mg silicate porous bioceramics. This abnormal but expected improvement in strength in bioceramic scaffolds is equivalent or even superior to the mechanical requirement in load-bearing bone defects. The breakthrough is totally unexpected, and it quickly opens the door for the 3D printing bioceramics manufacture and large-area segmental bone defect repair applications.

Soft tissue-to-bone interfaces are complex structures that consist of gradients of extracellular matrix materials, cell phenotypes, and biochemical signals. These interfaces, called entheses for ligaments, tendons, and the meniscus, are crucial to joint function, transferring mechanical loads and stabilizing orthopedic joints. When injuries occur to connected soft tissue, the enthesis must be re-established to restore function, but due to structural complexity, repair has proven challenging. Tissue engineering offers a promising solution for regenerating these tissues. This prospective review discusses methodologies for tissue engineering the enthesis, outlined in three key design inputs: materials processing methods, cellular contributions, and biochemical factors.

Interfacing organic electrochemical transistors (OECTs) with biological systems holds considerable promise for building-sensitive biosensors and diagnostic tools. We present a simple model that describes the performance of biosensors in which an OECT is integrated with a biological barrier layer. Using experimentally derived parameters we explore the limits of sensitivity and find that it is dependent on the resistance of the barrier layer. This work provides guidelines on how to optimize biosensors in which OECTs transduce changes in the impedance of biological layers, including lipid bilayer membranes and confluent cell layers.

This paper reviews progress in ultraviolet (UV) optoelectronic devices based on AlGaN films and their quantum wells (QWs), grown by plasma-assisted molecular beam epitaxy. A growth mode, leading to band-structure potential fluctuations and resulting in AlGaN multiple QWs with internal quantum efficiency as high as 68%, is discussed. Atomic ordering in these alloys, which is different from that observed in traditional III–V alloys, and its effect on device performance is also addressed. Finally, progress in UV-light-emitting diodes, UV lasers, UV detectors, electroabsorption modulators, and distributed Bragg reflectors is presented.

Lattice resonances in nanoparticle arrays recently have gained a lot of attention because of the possibility to produce spectrally narrow resonant features in transmission and reflection as well as significantly increase absorption in the structures. Most of the efforts so far have been put to study these lattice resonances in dipole approximation. However, the recent research shows that higher multipoles not only produce resonant feature but are also involved in cross-coupling, affect each other, and induce a magnetoelectric response. In the present paper, we review the recent achievements in studying interplay and coupling of different multipoles in periodic nanoparticle arrays and share our vision on further progress of the field.

Because of its unique mechanical, chemical, and biological properties, 3D-printed polyether ether ketone (PEEK) has great potential as customized bone replacement and other metal alloy implant replacement. PEEK samples were printed using fused deposition modeling (FDM) and evaluated in terms of their dimensional accuracy, crystallinity, and mechanical properties. Crystallinity and mechanical properties increased with elevated chamber temperature and post-printing annealing. Variations of material properties from three printers are evident. Many factors affect the quality of 3D-printed PEEK. Future FDA regulations for 3D-printed products are needed for this highly customizable manufacturing process to ensure safety and effectiveness for biomedical applications.

Recent studies illustrate how machine learning (ML) can be used to bypass a core challenge of molecular modeling: the trade-off between accuracy and computational cost. Here, we assess multiple ML approaches for predicting the atomization energy of organic molecules. Our resulting models learn the difference between low-fidelity, B3LYP, and high-accuracy, G4MP2, atomization energies and predict the G4MP2 atomization energy to 0.005 eV (mean absolute error) for molecules with less than nine heavy atoms (training set of 117,232 entries, test set 13,026) and 0.012 eV for a small set of 66 molecules with between 10 and 14 heavy atoms. Our two best models, which have different accuracy/speed trade-offs, enable the efficient prediction of G4MP2-level energies for large molecules and are available through a simple web interface.

We report the classical molecular dynamics (MD) study of thermal stability of three two-dimensional (2D) titanium carbides Ti2C, Ti3C2, and Ti4C3 (MXenes). Thermal properties of 2D nanomaterials are of fundamental importance and raise particular interest due to their potential applications in nanoelectronics. To investigate the behavior of Tin+1Cn MXenes during heating, structural parameters such as Lindemann indexes, radial distribution functions, and atomistic configurations were calculated. The analysis of MD data allowed us to obtain approximate values of MXene degradation temperatures that are 1050, 1500, and 1700 K for Ti2C, Ti3C2, and Ti3C4 MXenes, respectively.

A living electrode construct that enables integration of cells within bionic devices has been developed. The layered construct uses a combination of non-degradable conductive hydrogel and degradable biosynthetic hydrogel to support cell encapsulation at device surfaces. In this study, the material system is designed and analyzed to understand the impact of the cell carrying component on electrode characteristics. The cell carrying layer is shown to provide a soft interface that supports extracellular matrix development within the electrode while not significantly reducing the charge transfer characteristics. The living layer was shown to degrade over 21 days with minimal swelling upon implantation.

A new phase of carbon named Q-carbon is found to be over 40% harder than diamond. This phase is formed by nanosecond laser melting of amorphous carbon and rapid quenching from the super-undercooled state. Closely packed atoms in molten metallic carbon are quenched into Q-carbon with 80–85% sp3 and the rest sp2. The number density of atoms in Q-carbon can vary from 40% to 60% higher than diamond cubic lattice, as the tetrahedra packing efficiency increases from 70% to 80%. Using this semiempirical approach, the corresponding increase in Q-carbon hardness is estimated to vary from 48% to 70% compared to diamond.

Polymer-based nanomaterials have captured increasing interest over the past decades for their promising use in a wide variety of applications including photovoltaics, catalysis, optics, and energy storage. Bottom-up assembly engineering based on the self- and directed-assembly of polymer-based building blocks has been considered a powerful means to robustly fabricate and efficiently manipulate target nanostructures. Here, we give a brief review of the recent advances in assembly and reconfigurability of polymer-based nanostructures. We also highlight the role of computer simulation in discovering the fundamental principles of assembly science and providing critical design tools for assembly engineering of complex nanostructured materials.

Piezoresponse force microscopy (PFM) has emerged as a powerful tool to characterize piezoelectric, ferroelectric, and multiferroic materials on the nanometer level. Much of the driving force for the broad adoption of PFM has been the intense research into piezoelectric properties of thin films, nanoparticles, and nanowires of materials as dissimilar as perovskites, nitrides, and polymers. Recent recognition of limitations of single-frequency PFM, notably topography-related cross-talk, has led to development of novel solutions such band-excitation (BE) methods. In parallel, the need for quantitative probing of polarization dynamics has led to emergence of complex time- and voltage spectroscopies, often based on acquisition and analysis of multidimensional datasets. In this perspective, we discuss the recent developments in multidimensional PFM, and offer several examples of spectroscopic techniques that provide new insight into polarization dynamics in ferroelectrics and multiferroics. We further discuss potential extension of PFM for probing ionic phenomena in energy generation and storage materials and devices.

Multifunctional materials with excellent biocompatibility and electron-transport properties are critical for the pursuit of point-of-care biosensing devices. The authors report the synthesis of zinc oxide–reduced graphene oxide (ZnO–rGO) nanocomposite for the fabrication of an electrochemical immunosensing test-bed for noninvasive onsite detection of oral cancer biomarker (interleukin-8, IL8). The immunosensor showed successful detection of IL8 at low concentration ranges, i.e., 100 fg/mL–5 ng/mL with a sensitivity of 12.46 ± 0.82 µA mL/ng and a detection limit of 51.53 ± 0.43 pg/mL. These results have been validated through in vitro investigations using real saliva samples spiked with IL8.

There is an increasing interest in the generation of well-defined nanoparticles (NPs) not only because of their size-related particular properties, but also because they are promising building blocks for more complex materials in nanotechnology.

Here, we will shortly introduce the gas-phase synthesis technology that has evolved rapidly in the last years and allows the fabrication of complex NPs with controllable and tuneable chemical composition and structure while keeping very good control over the size distribution. We will also address some limitations of the technology (stability over time, production yield, etc.) and discuss possible solutions.

Here, we report thiol-free thermal-injection synthesis of chalcopyrite (CuFeS2) nanocrystals (NCs) using iron (II) bromide (FeBr2), copper (II) acetaylacetonate (Cu(acac)2), and elemental sulfur (S). Controlled reaction temperature and growth time yield stable and phase-pure ternary CuFeS2 NCs exhibiting tetragonal crystal structure. With increasing growth time from 1 to 30 min, absorption peak slightly red shifts from 465 to 490 nm. Based on spectroscopic ellipsometry analysis, three electronic transitions at 0.652, 1.54, and 2.29 eV were found for CuFeS2 NC film. Also, CuFeS2 NC thin films are incorporated as hole transport layers in cadmium telluride solar cells reaching an efficiency of ~12%.

Based on density functional theory, we recently suggested that metastable α-WB2 is a promising candidate combining very high hardness with high toughness. These calculations further suggested that the addition of Tantalum supports the crystallization of α-structured W1−xTaxB2−z, with only minor reduction in toughness. Thus, various Ta containing WB2-based coatings have been synthesized using physical vapor deposition. With increasing Ta content, the hardness increases from ~41 GPa (WB2) to ~45 GPa (W0.74Ta0.26B2). In situ micromechanical cantilever bending tests exhibit fracture toughness KIC values of 3.7 to 3.0 MPa√m for increasing Ta content (single-phased up to 26 at.% Ta).

Different sized graphene quantum dots (GQDs) have been synthesized by an inexpensive wet chemical method using bird charcoal as a precursor. Obtained GQDs found to have luminescence and visible light absorption. These GQDs are further coupled with titanium dioxide (TiO2) to form TiO2–GQDs nanocomposites. GQD nanostructures exhibit band gap tunability and have the potential to enhance the photoabsorption in TiO2. The hybrid combination of the nanomaterials decrease the recombination of charge carriers, increase charge carrier mobility, and improve the overall photoconversion efficiency. The composites exhibit higher photocatalytic activity and rate constants value than pure TiO2.