Gold nanorods have been receiving extensive attention owing to their extremely attractive applications in biomedical technologies, plasmon-enhanced spectroscopies, and optical and optoelectronic devices. The growth methods and plasmonic properties of Au nanorods have therefore been intensively studied. In this review, we present a comprehensive overview of the flourishing field of Au nanorods in the past five years. We will focus mainly on the approaches for the growth, shape and size tuning, functionalization, and assembly of Au nanorods, as well as the methods for the preparation of their hybrid structures. The plasmonic properties and the associated applications of Au nanorods will also be discussed in detail.

Gold nanorods and their plasmonic properties

Chemical methods developed over the past two decades enable preparation of colloidal nanocrystals with uniform size and shape. These Brownian objects readily order into superlattices. Recently, the range of accessible inorganic cores and tunable surface chemistries dramatically increased, expanding the set of nanocrystal arrangements experimentally attainable. In this review, we discuss efforts to create next-generation materials via bottom-up organization of nanocrystals with preprogrammed functionality and self-assembly instructions. This process is often driven by both interparticle interactions and the influence of the assembly environment. The introduction provides the reader with a practical overview of nanocrystal synthesis, self-assembly, and superlattice characterization. We then summarize the theory of nanocrystal interactions and examine fundamental principles governing nanocrystal self-assembly from hard and soft particle perspectives borrowed from the comparatively established fields of micro...

Self-Assembly of Colloidal Nanocrystals: From Intricate Structures to Functional Materials

Advanced energy conversion and storage (ECS) devices (including fuel cells, photoelectrochemical water splitting cells, solar cells, Li-ion batteries and supercapacitors) are expected to play a major role in the development of sustainable technologies that alleviate the energy and environmental challenges we are currently facing. The successful utilization of ECS devices depends critically on synthesizing new nanomaterials with merits of low cost, high efficiency, and outstanding properties. Recent progress has demonstrated that nanostructured metal chalcogenides (MCs) are very promising candidates for efficient ECS systems based on their unique physical and chemical properties, such as conductivity, mechanical and thermal stability and cyclability. In this review, we aim to provide a summary on the liquid-phase synthesis, modifications, and energy-related applications of nanostructured metal chalcogenide (MC) materials. The liquid-phase syntheses of various MC nanomaterials are primarily categorized with the preparation method (mainly 15 kinds of methods). To obtain optimized, enhanced or even new properties, the nanostructured MC materials can be modified by other functional nanomaterials such as carbon-based materials, noble metals, metal oxides, or MCs themselves. Thus, this review will then be focused on the recent strategies used to realize the modifications of MC nanomaterials. After that, the ECS applications of the MC/modified-MC nanomaterials have been systematically summarized based on a great number of successful cases. Moreover, remarks on the challenges and perspectives for future MC research are proposed (403 references).

Nanostructured metal chalcogenides: synthesis, modification, and applications in energy conversion and storage devices

The main challenge for all electrical, mechanical and optical sensors is to detect low molecular weight (less than 400 Da) chemical and biological analytes under extremely dilute conditions. Surface plasmon resonance sensors are the most commonly used optical sensors due to their unique ability for real-time monitoring the molecular binding events. However, their sensitivities are insufficient to detect trace amounts of small molecular weight molecules such as cancer biomarkers, hormones, antibiotics, insecticides, and explosive materials which are respectively important for early-stage disease diagnosis, food quality control, environmental monitoring, and homeland security protection. With the rapid development of nanotechnology in the past few years, nanomaterials-enhanced surface plasmon resonance sensors have been developed and used as effective tools to sense hard-to-detect molecules within the concentration range between pmol and amol. In this review article, we reviewed and discussed the latest trend and challenges in engineering and applications of nanomaterials-enhanced surface plasmon resonance sensors (e.g., metallic nanoparticles, magnetic nanoparticles, carbon-based nanomaterials, latex nanoparticles and liposome nanoparticles) for detecting “hard-to-identify” biological and chemical analytes. Such information will be viable in terms of providing a useful platform for designing future ultrasensitive plasmonic nanosensors.

Nanomaterials enhanced surface plasmon resonance for biological and chemical sensing applications

Gold Nanomaterials at Work in Biomedicine

We report an improved synthesis of colloidal gold nanorods (NRs) by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to ∼0.05 M as opposed to 0.1 M in well-established protocols. The method optimizes the synthesis for each of the 11 additives studied, allowing a rich array of monodisperse gold NRs with longitudinal surface plasmon resonance tunable from 627 to 1246 nm to be generated. The gold NRs form large-area ordered assemblies upon slow evaporation of NR solution, exhibiting liquid crystalline ordering and several distinct local packing motifs that are dependent upon the NR’s aspect ratio. Tailored synthesis of gold NRs with simultaneous improvements in monodispersity and dimensional tunability through rational introduction of additives will not only help to better understand the mechanism of seed-mediated growth of gold NRs but also advance the research on plasmonic metamaterials incorporating anisotropic metal nanostructures.

Improved Size-Tunable Synthesis of Monodisperse Gold Nanorods through the Use of Aromatic Additives

Monodisperse 3.1 nm Ag2Te NCs show a sharp optical absorption feature at 1154 nm with a large linear temperature dependence and the photoconductive response consistent with semiconducting character in Ag2Te NCs. The wavelength of the resonance is within the window of transparency for biological tissue making it a potential in vivo temperature marker or transducer for in situ heating with deep-penetrating near-infrared radiation.

Near-infrared absorption of monodisperse silver telluride (Ag 2Te) nanocrystals and photoconductive response of their self-assembled superlattices

Photonic and optoelectronic devices have been limited in most two-dimensional (2D) materials. Researchers have attempted diverse device structures, such as introducing some ferroelectric materials to form new hybrid materials that could improve the performance of these 2D devices. Ferroelectrics might adjust the carrier concentration, mobility, and bandgap of 2D materials to achieve non-volatile control of the photonic and optoelectronic properties. On the other hand, ferroelectrics have a spontaneous electric polarization that occurs below the Curie temperature and reverses under an applied electric field. The polarization can be modulated via incident light, while the light wavelengths can be tuned through switching the electric polarization. This could improve the performance of 2D photonic and optoelectronic devices. We believe that 2D materials, as an emerging member of 2D/ferroelectric hybrid materials, will have great potential in photonics and optoelectronics thanks to their tunable bandgap. Here, we provide a perspective of ferroelectrics on 2D materials for photonics and optoelectronics. We discuss the concept of ferroelectrics and their fundamentals and then present their unique advantages in optoelectronic devices.

https://aip.scitation.org/doi/pdf/10.1063/5.0094965

The rise of 2D materials/ferroelectrics for next generation photonics and optoelectronics devices

Graphene quantum dots are the latest addition to the low‐dimensional nanomaterial family, which have drawn growing attention due to their unique physiochemical properties and potential applications in many fields. However, their practical application is hindered by the high fabrication cost and environmental concerns regarding unsustainable carbon sources and routes. This work demonstrates a universal approach to fabricate various heteroatom(s) doped lignin‐derived graphene quantum dots (LGQDs) for utilization in the photoelectrochemical‐type photodetectors (PDs). The results indicate that LGQDs are endowed with relatively dopant‐rich chemical states and tailorable broadband photoluminescence. Based on these advantages, these novel LGQDs‐based PDs present obvious and fast photo‐response within the visible region, as well as good long‐term stability in the mild neutral environment, suggesting their great practical significance. It is believed that this work paves a new way for developing PDs based on the photochemically active species from sustainable and cheap biomass‐derived lignin.

Application of Lignin‐Derived Graphene Quantum Dots in Visible Light‐Driven Photoelectrochemical Photodetector

Violet phosphorus (VP) is a stable layered van der Waals phosphorus allotrope with unique electronic and optoelectronic properties. In this study, 2D VP nanosheets (NSs) are prepared by liquid phase exfoliation (LPE) method under ambient conditions. The prepared VP NSs are characterized and utilized for photoelectrochemical (PEC)‐type photodetector (PD). The systematic PEC measurements reveal that the as‐prepared VP‐based PD shows tunable photo‐response activities from ultraviolet to visible region. A current density of 0.52 µA cm−2, a photo‐responsivity of 31.70 µA W−1, and a detectivity of 7.92 × 1010 Jones can be obtained in 1.0 m KOH under 350 nm irradiation at 0 V, revealing the good self‐powered capability of VP‐based PD. Furthermore, the cycle and time stability tests exhibit the good chemical and environmental stability of the as‐prepared PD via processing 10 000 s on/off switching and placing after one month. It is expected that this work can offer an understanding of a PEC‐type VP NSs‐based PD, and highlight the further promising applications of 2D VP NSs for other optoelectronic devices.

Linghua Jin

Papers

Improved Size-Tunable Synthesis of Monodisperse Gold Nanorods through the Use of Aromatic Additives

Near-infrared absorption of monodisperse silver telluride (Ag 2Te) nanocrystals and photoconductive response of their self-assembled superlattices

The rise of 2D materials/ferroelectrics for next generation photonics and optoelectronics devices

Application of Lignin‐Derived Graphene Quantum Dots in Visible Light‐Driven Photoelectrochemical Photodetector

Ultrathin 2D Violet Phosphorus Nanosheets: Facile Liquid‐Phase Exfoliation, Characterization, and Photoelectrochemical Application