Nature Reviews Materials最新文献

Vision is crucial for intelligent machines to detect and interact with their environments. However, conventional artificial vision systems (AVS) are hindered by several limitations, including narrowed field of view, optical aberrations, limited adaptability and suboptimal efficiency. Advancements in nanomaterials have facilitated the development of biomimetic optoelectronics that structurally or functionally mimic biological eyes. Two main approaches have revolutionized AVS: biomimetic designs that replicate the superior optical performance of biological eyes, enhancing the field of view, imaging quality and adaptability, and neuromorphic optoelectronics that integrate processing functions at the sensory endpoints, thus boosting computational and energy efficiency. This Review emphasizes nanomaterial-based biomimetic optoelectronics, featuring novel curved image sensors and neuromorphic devices. We delve into advanced nanomaterials and innovative design strategies that underpin these novel AVS. This Review aims to offer valuable insights to inspire researchers to advance the development of next-generation vision devices.

Binding energy (B_E) referencing is critical to the reliability of chemical analysis performed by X-ray photoelectron spectroscopy. Although the procedure is straightforward for metallic samples, no universal solution is available for insulators, wherein a build-up of positive charge during photoemission results in an uncontrolled change in the B_E of the core-level peaks. As these peaks are used to assess the chemical bonding, shifts caused by charging lead to problems with spectra interpretation and contribute to an unacceptably large spread in the B_E values reported for the same chemical state. It is often unclear which referencing methods should be applied to which sample type and which referencing approaches should be rejected. In this Perspective, we review essential concepts and key experiments related to B_E referencing. We discuss energy diagrams and appropriate reference levels for conducting and insulating samples with and without electrical contact with the spectrometer, and we define criteria for the ultimate charge-reference method, using them to evaluate common referencing techniques. Although no method is free of issues, the most popular one, based on the adventitious carbon (AdC), turns out to be the least reliable. In particular, because the vacuum level aligns at the AdC–sample interface, the B_E of the reference C 1s peak from AdC is not constant but varies with the sample work function. To rectify the situation, we suggest easy-to-do control experiments that refute the notion that the C 1s peak has constant B_E. We further use the framework of energy diagrams to explain the consequences of the vacuum level alignment at the AdC–sample interface for measurements performed in the most common experimental configurations. Finally, we suggest ideas for improving the reliability of chemical analysis to stimulate the development of new referencing standards.

Organic two-dimensional crystals (O2DCs) are a class of synthetic layered materials, typically constructed from π-conjugated building blocks, that show extended in-plane π-conjugation and/or interlayer electronic couplings. They are synthesized either directly as monolayer to few-layer nanosheets or as bulk crystals that can be exfoliated. O2DCs display customizable topological structures and layer-dependent physical attributes, offering a versatile material platform for exploring intriguing electronic and quantum phenomena. In this Review, we discuss the structure–property relationships and synthetic strategies of O2DCs, with particular emphasis on their unique electronic structures, charge transport properties and the emergence of quantum states, such as topological and superconducting phases, alongside different spin states. Furthermore, we highlight emerging device applications of O2DCs across electronics, optoelectronics and spintronics. Finally, we provide an outlook on the persistent challenges in synthetic chemistry, physics and materials science that must be addressed to further advance this field.

Ligand-protected metal nanoclusters (NCs) are ultrasmall particles (<3 nm) that represent the molecular state of metal materials. Owing to their molecule-like structure — particularly their atomic precision and protein-like hierarchy — metal NCs feature numerous useful molecule-like properties, including discrete energy levels, strong luminescence, intrinsic magnetism and programmable catalytic activity. In this Review, by regarding metal NCs as metallic analogues of organic molecules, we summarize methodological and mechanistic advances in their precise synthesis at the molecular and atomic levels. We first decipher cluster structure based on a protein-like hierarchical scheme and discuss synthetic strategies that realize molecular monodispersity in these clusters. We resolve formation mechanisms of metal NCs at the molecular level, aiming to establish step-by-step reaction maps reminiscent of total synthesis routes of organic molecules. We then examine approaches to customize the composition and morphology of the metal core, metal–ligand interface and ligand shell at the atom level. This Review concludes with our perspectives on the future development of atomic precision chemistry in both metal NCs and other inorganic nanomaterials.

Tissue-like bioelectronics have emerged as practical, user-friendly and unobtrusive systems for seamless bidirectional integration with the human body. Two-dimensional materials, being led by the prototypical graphene, uniquely fit the task of creating ultrathin and functional interfaces with biological matter. In this Perspective, we comprehensively discuss 2D materials and their electrical, optical, environmental and mechanical properties relevant to bioelectronics. We present examples of 2D material-based bioelectronic devices for tissue interfacing (skintronics) and organ interfacing (organtronics). Importantly, we provide a roadmap for the future development of the field and highlight associated challenges yet to be solved.

Correction to: Nature Reviews Materials https://doi.org/10.1038/s41578-024-00702-0, published online 7 August 2024.