The oxidation chemistry of two-dimensional transition metal carbide MXenes has brought new research significance to their protection and application. However, the oxidation behavior and degradation mechanism of MXenes, in particular with time under oxygen conditions at room temperature, remain largely unexplored. Here, several experimental and theoretical techniques are used to determine a very early stage of the oxidation mechanism of HF-etched Ti₃C₂T_x (a major member of MXenes and T_x = surface functional groups) in an oxygen environment at room temperature. Aberration-corrected environmental transmission electron microscopy coupled with reactive molecular dynamics simulations show that the crystal plane-dependent oxidation rate of Ti₃C₂T_x and oxide expansion are attributed to differences in the coordination and charge of superficial Ti atoms, and the existence of the channels between neighboring MXene layers on the different crystal planes. The complementary x-ray photoelectron spectroscopy and Raman spectroscopy analyses indicate that the anatase and a tiny fraction of brookite TiO₂ successively precipitate from the amorphous region of oxidized Ti₃C₂T_x, grow irregularly and transform to rutile TiO₂. Our study reveals the early-stage structural evolution of MXenes in the presence of oxygen and facilitates further tailoring of the MXene performance employing oxidation strategy.

Outstanding charge transport in molecular crystals is of great importance in modern electronics and optoelectronics. The widely adopted strategies to enhance charge transport, such as restraining intermolecular vibration, are mostly limited to organic molecules, which are nearly inoperative in 2D inorganic molecular crystals currently. In this contribution, charge transport in 2D inorganic molecular crystals is improved by integrating charge-delocalized Se₈ rings as building blocks, where the delocalized electrons on Se₈ rings lift the intermolecular orbitals overlap, offering efficient charge transfer channels. Besides, α-Se flakes composed of charge-delocalized Se₈ rings possess small exciton binding energy. Benefitting from these, α-Se flake exhibits excellent photodetection performance with an ultrafast response rate (∼5 µs) and a high detectivity of 1.08 × 10¹¹ Jones. These findings contribute to a deeper understanding of the charge transport of 2D inorganic molecular crystals composed of electron-delocalized inorganic molecules and pave the way for their potential application in optoelectronics.

The simultaneous detection of multiple stimuli, such as pressure and temperature, has long been a persistent challenge for developing electronic skin (e-skin) to emulate the functionality of human skin. Meanwhile, the demand for integrated power supply units is an additional pressing concern to achieve its lightweightness and flexibility. Herein, we propose a self-powered dual temperature–pressure (SPDM) sensor, which utilizes a compressible ionic gel electrolyte driven by the potential difference between MXene and Al electrodes. The SPDM sensor exhibits a rapid and timely response to changes in pressure-induced deformation, while exhibiting a slow and hysteretic response to temperature variations. These distinct response characteristics enable the differentiation of current signals generated by different stimuli through machine learning, resulting in an impressive accuracy rate of 99.1%. Furthermore, the developed SPDM sensor exhibits a wide pressure detection range of 0–800 kPa and a broad temperature detection range of 5–75°C, encompassing the environmental conditions encountered in daily human life. The dual-mode coupled strategy by machine learning provides an effective approach for temperature and pressure detection and discrimination, showcasing its potential applications in wearable electronics, intelligent robots, human–machine interactions, and so on.

Modulation of light underpins a central part of modern optoelectronics. Conventional optical modulators based on refractive-index and absorption variation in the presence of an electric field serve as the workhorse for diverse photonic technologies. However, these approaches based on electro-refraction or electro-absorption effect impose limitations on frequency converting and signal amplification. Lanthanide-activated phosphors offer a promising platform for nonlinear frequency conversion with an abundant spectrum. Here, we propose a novel approach to achieve frequency conversion and digital modulation of light signal by coupling lanthanide luminescence with an electrically responsive ferroelectric host. The technological benefits of such paradigm-shifting solution are highlighted by demonstrating a quasi-continuous and enhancement of the lanthanide luminescence. The ability to locally manipulate light emission can convert digital information signals into visible waveforms, and visualize electrical logic and arithmetic operations. The proof-of-concept device exhibits perspectives for developing light-compatible logic functions. These results pave the way to design more controllable lanthanide photonics with desired opto-electronic coupling.

We use an automated research platform combined with machine learning to assess and understand the resilience against air and light during production of organic photovoltaic (OPV) devices from over 40 donor and acceptor combinations. The standardized protocol and high reproducibility of the platform results in a dataset of high variety and veracity to deploy machine learning models to encounter links between stability and chemical, energetic, and morphological structure. We find that the strongest predictor for air/light resilience during production is the effective gap E_g,eff which points to singlet oxygen rather than the superoxide anion being the dominant agent in degradation under processing conditions. A similarly good prediction of air/light resilience can also be achieved by considering only features from chemical structure, that is, information which is available prior to any experimentation.

Flexible electronics has emerged as a continuously growing field of study. Two-dimensional (2D) materials often act as conductors and electrodes in electronic devices, holding significant promise in the design of high-performance, flexible electronics. Numerous studies have focused on harnessing the potential of these materials for the development of such devices. However, to date, the incorporation of 2D materials in flexible electronics has rarely been summarized or reviewed. Consequently, there is an urgent need to develop comprehensive reviews for rapid updates on this evolving landscape. This review covers progress in complex material architectures based on 2D materials, including interfaces, heterostructures, and 2D/polymer composites. Additionally, it explores flexible and wearable energy storage and conversion, display and touch technologies, and biomedical applications, together with integrated design solutions. Although the pursuit of high-performance and high-sensitivity instruments remains a primary objective, the integrated design of flexible electronics with 2D materials also warrants consideration. By combining multiple functionalities into a singular device, augmented by machine learning and algorithms, we can potentially surpass the performance of existing wearable technologies. Finally, we briefly discuss the future trajectory of this burgeoning field. This review discusses the recent advancements in flexible sensors made from 2D materials and their applications in integrated architecture and device design.

Low-temperature zinc batteries (LT-ZIBs) based on aqueous electrolytes show great promise for practical applications owing to their natural resource abundance and low cost. However, they suffer from sluggish kinetics with elevated energy barriers due to the dissociation of bulky Zn(H₂O)₆²⁺ solvation structure and free Zn²⁺ diffusion, resulting in unsatisfactory lifespan and performance. Herein, dissimilar to solvation shell tuning or layer spacing enlargement engineering, delocalized electrons in cathode through constructing intrinsic defect engineering is proposed to achieve a rapid electrocatalytic desolvation to obtain free Zn²⁺ for insertion/extraction. As revealed by density functional theory calculations and interfacial spectroscopic characterizations, the intrinsic delocalized electron distribution propels the Zn(H₂O)₆²⁺ dissociation, forming a reversible interphase and facilitating Zn²⁺ diffusion across the electrolyte/cathode interface. The as-fabricated oxygen defect-rich V₂O₅ on hierarchical porous carbon (ODVO@HPC) electrode exhibits high capacity robustness from 25 to –20°C. Operating at –20°C, the ODVO@HPC delivers 191 mAh g^–1 at 50 A g^–1 and lasts for 50 000 cycles at 10 A g^–1, significantly enhancing the power density and lifespan under low-temperature environments in comparison to previous reports. Even with areal mass loading of ∼13 mg cm^–2, both coin cells and pouch batteries maintain excellent stability and areal capacities, realizing practical high-performance LT-ZIBs.