In article number 2007486, Liang Cheng, Chaoliang Tan, and co-workers report the activation of the near infrared absorption of layered metal oxide nanomaterials via a simple lithium treatment-induced structural engineering, making them promising as robust biodegradable nanoagents for photothermal cancer therapy in the second near infrared window.
Abstract The remarkable successes of graphene have sparked increasing interest in elemental two‐dimensional (2D) materials, also referred to as Xenes. Due to their chemical simplicity and appealing physiochemical properties, Xenes have shown particular potential for numerous (opto) electronic, iontronic, and energy applications. Among them, layered α‐phase tellurene has demonstrated the most promise, thanks to the recent successes in the chemical synthesis of highly crystalline 2D tellurene. However, the general electronic and electrochemical properties of tellurene in electrolyte systems remain ambiguous, hindering their further development. In this work, we studied the electrostatic gating, electrocatalysis, and electrochemical stability of tellurene in electrolyte systems. Our results show that tellurene obtained from both hydrothermal and chemical vapor deposition methods, two mainstream synthetic approaches for Xenes, demonstrates thickness‐dependent ambipolar transport with high hole mobility and stability in both aqueous electrolytes and ionic liquids. More importantly, the electrochemical properties of tellurene are investigated via the emerging on‐chip electrochemistry. Pristine tellurene demonstrates hydrogen evolution reaction with low Tafel slopes and remarkable electrochemical stability in acidic electrolytes over a large potential window. Our study provides a comprehensive understanding of the iontronic and electrochemical properties of tellurene, paving the way for the broad adoption of Xenes in sensors, synaptic devices, and electrocatalysis.
Tellurium (Te) has been rediscovered as an appealing p-type van der Waals semiconductor for constructing various advanced devices. Its unique crystal structure of stacking of one-dimensional molecular chains endows it with many intriguing properties including high hole mobilities at room temperature, thickness-dependent bandgap covering short-wave infrared and mid-wave infrared region, thermoelectric properties, and considerable air stability. These attractive features encourage it to be exploited in designing a wide variety of optoelectronics, especially infrared photodetectors. In this Perspective, we highlight the important recent progress of optoelectronics enabled by Te nanostructures, which constitutes the scope of photoconductive, photovoltaic, photothermoelectric photodetectors, large-scale photodetector array, and optoelectronic memory devices. Prior to that, we give a brief overview of basic optoelectronic-related properties of Te to provide readers with the knowledge foundation and imaginative space for subsequent device design. Finally, we provide our personal insight on the challenges and future directions of this field, with the intention to inspire more revolutionary developments in Te-based optoelectronics.
Synergistic integration of a fine-tuned chiral donor with hybrid long/short-range charge-transfer offers desirable circularly polarized emitters with both a high dissymmetry factor of 1.6 × 10 −3 and maximum external quantum efficiency of 37.4%.
In this era of artificial intelligence and Internet of Things, emerging new computing paradigms such as in-sensor and in-memory computing call for both structurally simple and multifunctional memory devices. Although emerging two-dimensional (2D) memory devices provide promising solutions, the most reported devices either suffer from single functionalities or structural complexity. Here, this work reports a reconfigurable memory device (RMD) based on MoS
Low-resistance contact has long been pursued in the two-dimensional (2D) electronic/optoelectronic device community. Still, an economy-efficient method highly compatible with the conventional 2D device fabrication process in laboratory remains to be explored. Herein, we report a plasma-optimized contact strategy for high-performance PdSe2 nanoflake-based field-effect transistors (FETs). Selenium vacancies created by air plasma can introduce p-type doping in the contact area, thus optimizing the device performance. The effect of plasma treatment on PdSe2 nanoflake is corroborated by high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy spectrum, atomic force microscopy, and Kelvin probe force microscopy. The PdSe2 FET with plasma-optimized contact exhibits significantly improved field-effect carrier mobilities, current on/off ratios, and reduced contact resistance than that without plasma treatment fabricated from the same PdSe2 nanoflake. Moreover, this strategy has also been proven effective to prepare high-performance FETs based on 2D WSe2 and MoSe2 nanoflakes, further demonstrating its application prospect.
Abstract Layered metal oxides including MoO 3 and WO 3 have been widely explored for biological applications owing to their excellent biocompatibility, low toxicity, and easy preparation. However, they normally exhibit weak or negligible near‐infrared (NIR) absorption and thus are inefficient for photo‐induced biomedical applications. Herein, the structural engineering of layered MoO 3 and WO 3 nanostructures is first reported to activate their NIR‐II absorption for efficient photothermal cancer therapy in the NIR‐II window. White‐colored micrometre‐long MoO 3 nanobelts are transformed into blue‐colored short, thin, defective, interlayer gap‐expanded MoO 3− x nanobelts with a strong NIR‐II absorption via the simple lithium treatment. The blue MoO 3− x nanobelts exhibit a large extinction coefficient of 18.2 L g −1 cm −1 and high photothermal conversion efficiency of 46.9% at 1064 nm. After surface modification, the MoO 3− x nanobelts can be used as a robust nanoagent for photoacoustic imaging‐guided photothermal therapy to achieve efficient cancer cell ablation and tumor eradication under irradiation by a 1064 nm laser. Importantly, the biodegradable MoO 3− x nanobelts can be rapidly degraded and excreted from body. The study highlights that the structural engineering of layered metal oxides is a powerful strategy to tune their properties and thus boost their performances in given applications.
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