Analog Resistive Memories

In article number 2109970, Armantas Melianas, Armin VahidMohammadi, Alberto Salleo, Mahiar Max Hamedi, and co-workers present the world's first electrochemical transistor memory based on 2D materials (MXene). These transistors can be used for neuromorphic computers, where they are a thousand times faster than previous ionic memories and other state-of-the-art technologies like resistive- or phase-change memristors (Image credit: Armin VahidMohammadi).

Reprogramming Tumor-Associated Macrophages

In article number 2108971, Zhen Li and co-workers find that ultra-small Cu_2−xSe nanoparticles can effectively polarize tumor-associated macrophages (TAMs) from the tumor-supportive M2 phenotype into anti-tumor M1 phenotype to significantly boost anti-tumor immunity through a novel mechanism. The nanoparticles can generate reactive oxygen species to trigger polarization through the novel ROS-TRAF6-IRF5-IL-23 signaling pathway, rather than the classic ROS-NF-?B-iNOS pathway.

Fatty Liver Detection

In article number 2109929, Fuyou Li, Yuling Qin, Li Wu, and co-workers demonstrate an effective strategy to construct a NIR-I/NIR-II fluorescent probe with a highly sensitive response to environment polarity, ultrabright emission, and superior photostability for specific intracellular lipid droplet imaging in living cells and in vivo. The findings promote the potential of fluorescence imaging for realtime fatty liver disease analysis in vivo.

Ultrasensitive Molecular Sensors

In article number 2106830, Nicholas R. Glavin and co-workers describe a real-time impedance spectroscopy approach, which enables ultrasensitive molecular sensors in solution processed 2D nanomaterials. Through bypassing traditionally dominant interflake interactions and selectively extracting intraflake doping effects, detection of NO₂ vapor down to 1 ppb is readily achievable with an ultimate limit of detection approaching 63 ppt. Image by Dr. Jo Richers (www.jorichers.com).

Aiming to enhance the doping efficiency, basic knowledge on the molecular doping process and promotion strategies including the energy level control, morphology modification, counter ion engineering, and dopant activation are introduced. Based on the achievable high-efficiency doping process, future directions and outlooks are presented.

The internal electric field (IEF) holds huge advantages in the directional migration of charge carriers. Modulations with detailed subdivision, determinations from theoretical and experimental characterizations and relevant applications in solar cell, photodetector, catalysis and characteristic control in terms of the IEF are summarized.

Nickel-based materials have attracted much attention in rechargeable batteries including Li-ion batteries, Na-ion batteries, Li–S batteries, Ni-based aqueous batteries, and metal–air batteries.

In this review, several modification strategies and insights into the mechanism of TiO₂ are highlighted to make full use of near-infrared light, which accounts for about 52% of sunlight for photocatalytic energy conversion and storage. Moreover, its broad application prospects in clean energy production, chemical synthesis, and environmental purification are also summarized.

This review begins with a discussion of macrophages and the polarization of macrophages in the different microenvironments of conventional and chronic wounds. Then, recent advances in biomaterials that balance the macrophage phenotype in wound healing are highlighted. Finally, looking ahead, the potential ability of biomaterial scaffolds to modulate immune signaling to produce an environment conducive to regeneration is discussed.

Electrochemical random-access memories using multilayered 2D titanium carbide MXene that combine the speed, linearity, write noise, switching energy, and endurance metrics essential for parallel acceleration of artificial neural networks with near ideal numerical accuracy in image recognition simulations are reported. The multilayered 2D MXene films are also stable after heat treatment needed for back-end-of-line integration with Si electronics.

Ultrasmall Cu_2−xSe nanoparticles can effectively polarize tumor-supportive M2-like tumor-associated macrophages to the anti-tumor M1 phenotype to boost tumor immunotherapy through a novel mechanism. The generated reactive oxygen species can elicit auto-ubiquitination of tumor necrosis factor receptor-associated factor 6 to activate and enhance the expression and nuclear translocation of interferon regulatory factor 5 to facilitate the expression of interleukin-23.

An effective strategy to construct a NIR-I/NIR-II fluorescent probe with highly sensitive response to environment polarity, ultrabright emission, and superior photostability is reported. Using a NIR-I and NIR-II fluorescence imaging strategy, the as-designed probes are successfully applied to high-resolution vessel imaging, real-time and contact-free monitoring of heartbeat and respiratory, and fatty liver disease analyzing in vivo.

The implementation of a real-time impedance spectroscopy approach results in ultrasensitive molecular sensors based on solution processed 2D nanomaterials. Through bypassing traditionally dominant interflake interactions and selectively extracting intraflake doping effects, detection of NO₂ down to 1 ppb is readily achievable with an ultimate limit of detection of 63 ppt.

Nitrogen Photofixation

In article number 2112452, Xusheng Zheng and co-workers present N2 photofixation to ammonia over a CoO-supported Ru single-atom catalyst. The Ru-Co coordination between Ru single atoms (yellow spheres) and Co atoms (blue spheres) serves as an additional electron transfer channel. This channel promotes more photogenerated electrons to accumulate at Ru atoms, thus increasing photoelectron density and N2 photofixation performance over Ru active sites.

The extra RuCo coordination from the strong interaction between Ru single atoms and the second coordination sphere serves as an additional electron transfer channel in CoO-supported Ru single-atom catalysts. Such channel promotes more photogenerated electrons to accumulate at Ru sites instead of Co sites, thus increasing photoelectron density and N₂ photofixation performance over Ru active sites.

Oxygen vacancies are implanted into orthorhombic niobium pentoxide (T-Nb₂O₅) particles via acid immersion of Nb₂O₅·nH₂O with the formation of Lewis acid sites. The enrichment of oxygen vacancies endows T-Nb₂O_5−x with much higher electric conductivity, better electrochemical kinetics, larger pseudocapacitive contribution. O-doped graphitic C₃N₄ is creatively proposed as trace oxygen pump to repair excessive oxygen vacancies.

Zero-valent Pt single atoms incorporated into the carbon supported α-MoC_1−x nanoparticles act as a pH-universal hydrogen evolution reaction (HER) catalyst. Theoretical calculations combined with X-ray absorption spectroscopy reveal that the Pt atom achieves the zero-valent state due to the atomic charge polarization, which further optimizes the adsorption/desorption energy of intermediates, accelerating reaction dynamics of the HER.

The voltage window of a MnO/MnS@BCN symmetrical supercapacitor is broadened to 2.0 V through the synergistic effect between boroncarbonitrides and the MnO/MnS heterostructure, which doubles the single-component devices.

In 3D chiral metacrystals, the chiroptical properties can be finely tuned by in-plane and out-of-plane diffractive coupling. The proposed concept could be suitable for integration with quantum emitters and open perspectives in novel schemes of enantiomeric detection.

The phase segregation of mixed-halide perovskite solar cells induces a locally shifted bandgap, hinders the charge-carrier transport, and increases the bulk recombination. By suppressing the phase segregation, the open-circuit voltage is improved from 1.15 to 1.20 V.

This study reports on novel solution-processed fullerene derivatives, namely indene-C60-propionic acid butyl ester and indene-C60-propionic acid hexyl ester, as the interlayers in narrow-bandgap perovskite solar cells as well as tandem solar cells. Their effects on the performance and non-radiative recombination in the devices are systematically studied.

Injectable adhesive hydrogels capable of closing moist and dynamic wounds are developed with multiple moist adhesion mechanisms and bulk double-crosslinked structures. The adhesive hydrogels exhibit high mechanical resilience, effective energy dissipation, and desirable tissue adhesion in a moist and dynamic physiological environment for wound closure and healing on vulnerable joint skin.

A rapid lithium diffusion-controlling alloy layer is screened and it displays dramatically high resistance to moisture corrosion under a practical ambient humidity, which is verified by interface-sensitive sum frequency generation spectroscopy. The pre-treated electrode, after exposure for 60 min, can survive for 400 h with stable overpotentials of 18 mV, indicating its superiority and fabrication in practice.

A flash synthesis strategy of supramacromolecular deoxyribonucleic acid (DNA) hydrogel is presented. The super-fast gelation (within 1 s) depends on the supramacromolecular assembly of DNA chains and upconversion nanoparticles (UCNPs). Based on the rationally designed DNA chains and UCNPs, the hydrogel enables the efficient isolation of specific cells, and protects cells from the damage of near-infrared irradiation through upconversion effect.

Large organic piperazine cations are incorperated into 3D FASnI₃ lattice to form a FA_1−2yPZ_2ySn_1−yI₃ (0 ≤ y ≤ 0.25) structure, which effectively suppresses bulk defect formation and guarantees the continuity of [SnI₆] octahedral structures to promote the device photovoltaic performance with reduced bulk defects and unobstructed carrier transport.

Herein, a bisalt polyether electrolyte with high voltage tolerance and good interfacial contact is prepared via in situ polymerization process. This design endows the bisalt gel polymer electrolyte with good oxidation stability and excellent performance in both symmetrical batteries and Li metal full batteries. In situ FTIR tests provides an effective approach for interfacial mechanism studies.

An electron-enriched cobalt site is developed via an electronic structure modulation strategy with dopants and vacancies for accelerating water dissociation kinetics of alkaline water electrolysis.

Van der Waal (VdW) doping is investigated and applied to germanium sulfide transistors using layered black phosphorus. This VdW doping results in the observation of resonant tunneling at room temperature coupled with a conductivity switch to n-type semiconductor. Van der Waal doping can be a promising method for future nanoelectronics applications.

Cellulose cholesteric liquid crystals with abundant molecular interactions and dynamic regulations are presented as a bionic prototype for biological structural coloration.

An organic–inorganic nanoprobe is developed via direct anchoring of gold nanoparticles over the self-assembled thiol-tailed pyrene nanostructures via AuS interactions, demonstrating an efficient contrast agent for X-ray computed tomography imaging.

The dynamic soft elasticity of nematic elastomers causes strong adhesion on their surface. The effect of load pressure, the time of adhesion and the speed of detachment are studied, and good matching is obtained with theoretical models. When the elastomer is in the isotropic or glass phase, they are no longer adhesive, offering reversible control of the strength of adhesion.

Iodine (I)-containing polymer/alloy layer-based lithium (Li) (IPA-Li) anode is constructed and further applied in Li–air batteries. Due to the synergy of the Li zinc (LiZn) alloy, polymer layer, and I-based species, the resultant cells display a low overpotential and superior cycling stability in pure O₂ as well as ambient air.

The ZnCo₂O₄ quantum dots (ZCO-QDs) are embedded in the hollow carbon nanocapsule, forming novel quantum dots-based catalyst delivery systems in Li-S batteries. The highly dispersed ZCO-QDs can not only effectively anchor and catalyze polysulfides on the S-cathode side, but also act as self-healing agents to repair the solid electrolyte interphase and Li metal surface on the anode side.

The goal of this work is to identify the predominant reason for material failure and prevent it. This is essential for the development of high-performance sodium-ion batteries. For biphasic-Na_2/3Ni_1/3Mn_2/3O₂ cathode, failure at the cathode–electrolyte interface has been proven to be the culprit for the decline in electrochemical performance. Therefore, atomic layer deposition is a suitable modification strategy that can suppress failure and improve performance.

Stacked organic light-emitting diodes (OLEDs) that emit two different colors depending on the polarity of the applied voltage are tailored to stimulate tandem photosensitive proteins. As a result, the OLEDs successfully control ion currents in optogenetically modified ND7/23 cells and activate and inhibit motoneurons in Drosophila melanogaster larvae.

Acetic acid (HAc) is first introduced to reduce the supersaturated concentration of the precursor solution to form pre-nucleation clusters, thus inducing rapid nucleation. In particular, the introduction of HAc can inhibit the oxidation of Sn²⁺ and reduce the loss of I^-. HAc-assisted device deliver a champion efficiency of 12.26%, maintaining ≈90% of initial efficiency after storage in nitrogen over 3000 h.

The interactions of electrons or holes with metal–organic frameworks (MOFs) are important for the systematic exploration of MOFtronics and investigation of the related structure–property correlation optimization. Herein, ultrathin copper tetrakis(4-carboxyphenyl)porphyrin nanosheets exhibit good electron and hole trapping capability superior to its ligand tetrakis(4-carboxyphenyl)porphyrin and ranks high in current nanofloating gate materials.

A general strategy is developed to fabricate various types of inorganic nanosheets (NSs) with high-loading single-atom catalysts (SACs). N-doped graphene sacrificial template loaded with high-loading Pt SACs can successfully transfer the SACs onto NSs-structured support materials composed of binary and ternary metal oxides and metal. The SACs possess high thermal stability, owing to strong covalent metal–support interactions.

Metabolism-driven nanoprobes (HF-D-Ala NPs) with quenched fluorescence are formed via self-assembly of amphiphilic fluorescent small-molecule (HF-D-Ala). Under bacterial metabolism, HF-D-Ala NPs are disassembled into free HF-D-Ala that can be further integrated into cell walls and “turn-on” the molecular fluorescence, realizing specific bacterial detection and imaging. The detected bacteria are subsequently inactivated by CO released from incorporated HF-D-Ala upon visible-light.

An unprecedented polymer material with a dramatic and reversible water-induced stiffening (stiffness increase as much as 10⁴ times) is introduced based on phase separation, differing from traditional ones that are usually weakened upon hydration. A universal approach for water-induced stiffening is proposed and verified on various systems. This work would pave the way for the design and development of water-responsive polymer materials.

In this work, kirigami structural design and self-healable conductive materials establish a novel conformal electronics strategy. Kirigami is shooting the conformal issues of non-stretchable materials by assembling the planar fabricating circuits into non-developable curved-surface. Furthermore, the Ag nano-particles and polycaprolactone self-healable conductive materials can realize conductivity via a simple heating process rather than complex 3D fabrication.

A versatile color changing system activated by various stimuli, including light, mechanical scratching, and stretch-and-release is reported based on introducing defects into a graphitic carbon nitride photocatalyst composited with polyvinyl alcohol. This dynamic system can be leveraged into multiple applications: 1) light activated rewritable paper; 2) light and mechanical writing surface erased by moisture; 3) color changing smart window.

Transparent refractory aerogel outperforms all selective absorbers with its combination of high transparency and thermal resistance.

Highly efficient hole transport layer-free low bandgap mixed Pb–Sn perovskite solar cells are realized using a binary additive system composed of CuSCN and GlyHCl. The improved charge transport and suppressed nonradiative recombination across the hole extractive interface have a marked impact on device performance, achieving the highest efficiency reported to date of 20.1%.

The layered reinforced concrete structure enables sulfur cathode with aligned through-channel and intertwined conductive network, leading to fast kinetics and strengthened integrity during cycling. Benefiting from the unique structure, the ultra-thick sulfur cathode delivers a high capacity of 10 mAh cm⁻² and excellent cycling life (80.8%) over 140 cycles under lean electrolyte (E/S=2) and limited lithium (N/P=2.7).

A doping strategy is introduced to fabricate an ultra-sensitive catalyst (iron-doped palladium nanocrystals (NCs)) for efficient chemodynamic therapy of tumors. The as-synthesized FePd-TPP NCs have an outstanding Fenton reaction catalytic efficiency for enhanced intracellular hydroxyl radical generation. After loading with adriamycin (ADM), the final FePd-TPP/ADM NCs exhibit a noticeable magnetic resonance imaging-guided combined chemo-/chemodynamic cancer nanotherapy.

In this work, a single-walled carbon nanotube (SWCNT) thin film plays the role of electrodes in lateral perovskite photodetector design. The femtosecond laser patterning of SWCNT film allows micron spatial resolution. Excellent contact is formed when perovskite cesium lead tribromide (CsPbBr₃) microcrystals are grown directly on top. As a result, flexible and extremely sensitive photodetector conserves high performance after 10 000 cycles of bending.

Ultrasmall bismuth nanoclusters are synthesized within carbon nano-bundles from bismuth-containing metal–organic framework for high-efficiency chloride-driven electrochemical deionization, boosting the advances of both non-noble metal nanoclusters and electrochemical desalination.

Fe is alloyed into Cs₂AgBiBr₆, extending the absorption edge to the near infrared (NIR) region (≈1350 nm), which is the longest absorption for lead-free perovskite. A new intermediate band, contributing to the NIR absorption, is observed, indicating a new way to extend the optical response for lead-free perovskite to NIR photodetectors and intermediate band photovoltaics.

Roll-to-roll fabrication of perovskite solar cells (PSCs) on flexible substrates represents a promising approach for commercialization. By using a triple cation perovskite and a novel passivation strategy by doping guanidinium iodide into poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, it is demonstrated that slot-die-coated PSCs under ambient environment enables millimeter-sized perovskite clusters, leading to a record power conversion efficiency of 12%.

By using organo-boron based emitters, an excellent hyperfluorescence (HF) OLED system is designed. As a result, a high external quantum efficiency (EQE) of over 40% and pure blue color with a CIE y coordinate of 0.15 are achieved. Further, a long lifetime (LT₅₀) of 440 h with the designed HF systems is reached. Additionally, the detailed parameters for such high EQE values are analyzed.