Mechanism, Material, Design, and Implementation Principle of Two-Dimensional Material Photodetectors

Two-dimensional (2D) materials may play an important role in future photodetectors due to their natural atom-thin body thickness, unique quantum confinement, and excellent electronic and photoelectric properties. Semimetallic graphene, semiconductor black phosphorus, and transition metal dichalcogenides possess flexible and adjustable bandgaps, which correspond to a wide interaction spectrum ranging from ultraviolet to terahertz. Nevertheless, their absorbance is relatively low, and it is difficult for a single material to cover a wide spectrum. Therefore, the combination of phototransistors based on 2D hybrid structures with other material platforms, such as quantum dots, organic materials, or plasma nanostructures, exhibit ultra-sensitive and broadband optical detection capabilities that cannot be ascribed to the individual constituents of the assembly. This article provides a comprehensive and systematic review of the recent research progress of 2D material photodetectors. First, the fundamental detection mechanism and key metrics of the 2D material photodetectors are introduced. Then, the latest developments in 2D material photodetectors are reviewed based on the strategies of photocurrent enhancement. Finally, a design and implementation principle for high-performance 2D material photodetectors is provided, together with the current challenges and future outlooks.

Prussian blue as a co-catalyst for enhanced Cr(vi) photocatalytic reduction promoted by titania-based nanoparticles and aerogels

A nanostructured Prussian blue layer deposited on titania-based materials acts as an efficient electron acceptor/mediator greatly enhancing Cr(vi) photocatalytic reduction.

Cardiac troponin I photoelectrochemical sensor: {Mo368} as electrode donor for Bi2S3 and Au co-sensitized FeOOH composite

A suitable electron donor, which guarantees the stability of the whole system, is considered as the driving force of the PEC sensor. Nowadays, searching appropriate electron donor is still one of the orientations to explorate in the field of sensor. Na₄₈[H₄₉₆Mo₃₆₈O₁₄₆₄S₄₈]·ca.1000H₂O (abbr. {Mo₃₆₈}), as a type of polyoxometalate, has perfect morphology, definite size and unique electronic property. Due to the prominent water solubility, {Mo₃₆₈} usually releases small cations and exists as large anions in the ultrapure water. The interesting property endows {Mo₃₆₈} with excellent reducibility, which provides great feasibility to become an outstanding electron donor. In addition, FeOOH prepared through a simple operation owns high adsorption capacity, which ensures the fastness of other materials. Subsequently, the narrow band-gap of Bi₂S₃ and the unique noble metal properties of Au nanoparticles are utilized to co-sensitize FeOOH to improve the light-harvesting capability and photoelectric conversion efficiency. Combined with the specificity recognition of antigen and antibody, a novel photoelectrochemical sensor is constructed with a wide detection range of 1.00 pg mL^-1 - 100 ng mL^-1 and low detection limit (0.76 pg mL^-1), which achieves the sensitive detection of cardiac troponin I in early diagnosis of cardiovascular disease.

Ion-Selective Prussian-Blue-Modified Celgard Separator for High-Performance Lithium-Sulfur Battery

Application of Li-S batteries has been restricted because of their major problem, that is, shuttling of soluble polysulfides between electrodes, which results in serious capacity fading. For the development of high-performance Li-S batteries, we first time utilize a simple growth method to introduce a Prussian blue (PB)-modified Celgard separator as an ion-selective membrane. The unique structure of PB could effectively suppress the shuttle of polysulfides but scarcely affect the transfer ability of lithium ions, which is beneficial to achieve high sulfur conversion efficiency and capacity retention. The Li-S battery with PB-modified Celgard separator has an average capacity decay of only 0.03 % per cycle at 1 C after 1000 cycles.

Local structure of a switchable dielectric Prussian blue analogue

Two crystallographically similar phases of a dielectric framework material differ markedly in the rigidity of the cyanide framework.

An overview on emerging photoelectrochemical self-powered ultraviolet photodetectors

In recent years, as a new member of ultraviolet photodetectors (UV-PDs), photoelectrochemical UV-PDs (PEC UV-PDs) have received great attention. Compared to conventional photoconductors, PEC UV-PDs exhibit a number of merits, including low cost, environmentally friendly nature, being self-powered, and fast response. This tutorial review provides a comprehensive introduction to this research field, covering from the basics of performance evaluation of PEC UV-PDs, the state-of-the-art advances in structural design, electrolyte matching, and electrode fabrication of PEC UV-PDs, to the integration of multiple functions into a PEC UV-PD. In the end, we present our perspectives on the future development of PEC UV-PDs and highlight the key technical challenges in aiming to stimulate further developments in this research field.

Electrodeposition of Prussian blue films on Ni3Si2O5(OH)4 hollow nanospheres and their enhanced electrochromic properties

Porous PB films were electrodeposited on Ni₃Si₂O₅(OH)₄ hollow nanospheres, resulting in enhanced electrochromic properties due to the coarse substrate.

Photoenergy storage and power amplification strategy in membrane-less photoelectrochemical biofuel cells

We proposed a novel integrated PBFC by insetting a third electrode with high efficiency energy storage and release between the bioelectrode and the photoelectrode, resulting in a higher power output than that of the original PBFC.

Ultrafast switching of an electrochromic device based on layered double hydroxide/Prussian blue multilayered films

Electrochromic materials are the most important and essential components in an electrochromic device. Herein, we fabricated high-performance electrochromic films based on exfoliated layered double hydroxide (LDH) nanosheets and Prussian blue (PB) nanoparticles via the layer-by-layer assembly technique. X-ray diffraction and UV-vis absorption spectroscopy indicate a periodic layered structure with uniform and regular growth of (LDH/PB)n ultrathin films (UTFs). The resulting (LDH/PB)n UTF electrodes exhibit electrochromic behavior arising from the reversible K(+) ion migration into/out of the PB lattice, which induces a change in the optical properties of the UTFs. Furthermore, an electrochromic device (ECD) based on the (LDH/PB)n-ITO/0.1 M KCl electrolyte/ITO sandwich structure displays superior response properties (0.91/1.21 s for coloration/bleaching), a comparable coloration efficiency (68 cm(2) C(-1)) and satisfactory optical contrast (45% at 700 nm), in comparison with other inorganic material-based ECDs reported previously. Therefore, this work presents a facile and cost-effective strategy to immobilize electrochemically active nanoparticles in a 2D inorganic matrix for potential application in displays, smart windows and optoelectronic devices.

New faces of porous Prussian blue: interfacial assembly of integrated hetero-structures for sensing applications

Prussian blue (PB), the oldest synthetic coordination compound, is a classic and fascinating transition metal coordination material. Prussian blue is based on a three-dimensional (3-D) cubic polymeric porous network consisting of alternating ferric and ferrous ions, which provides facile assembly as well as precise interaction with active sites at functional interfaces. A fundamental understanding of the assembly mechanism of PB hetero-interfaces is essential to enable the full potential applications of PB crystals, including chemical sensing, catalysis, gas storage, drug delivery and electronic displays. Developing controlled assembly methods towards functionally integrated hetero-interfaces with adjustable sizes and morphology of PB crystals is necessary. A key point in the functional interface and device integration of PB nanocrystals is the fabrication of hetero-interfaces in a well-defined and oriented fashion on given substrates. This review will bring together these key aspects of the hetero-interfaces of PB nanocrystals, ranging from structure and properties, interfacial assembly strategies, to integrated hetero-structures for diverse sensing.

A universal method for the preparation of functional ITO electrodes with ultrahigh stability

A universal method for electrodeposition of various materials onto an indium tin oxide (ITO) coated substrate with high mechanical stability, which solves one of the most important problems concerning the modified ITO electrodes in practical applications, is presented.

A rapid-response electrochromic device with significantly enhanced electrochromic performance

Two same-material electrochromic layers were used to construct a novel electrochromic device (ECD) and it exhibited enhanced electrochromic properties.

Collagen nanofibers facilitated presynaptic maturation in differentiated neurons from spinal-cord-derived neural stem cells through MAPK/ERK1/2-Synapsin I signaling pathway

Neural stem cells (NSCs) are deemed to be a potential cell therapy for brain and spinal cord reconstruction and regeneration following injury. In this study, we investigated the role of nanofibrous scaffolds on NSCs-derived neurons in the formation of neural networks. Miniature excitatory postsynaptic currents (mEPSCs) were recorded using the whole-cell patch clamp recording method after the spinal cord-derived NSCs were differentiated into neurons and cultured in vitro for 10-14 days. It was observed that the frequency of mEPSCs in the differentiated neurons cultured on both randomly oriented and aligned collagen nanofibrous scaffolds was higher than that on the collagen-coated control and can be inhibited by an ERK inhibitor (PD98059), indicating that the collagen nanofibers affected the maturation of the synapses from presynaptic sites via the MAPK/ERK1/2 pathway. In addition, both of the collagen nanofibers increased the phosphorylation of Synapsin I and facilitated the interaction of p-ERK1/2 and p-Synapsin I. All these results suggested that the collagen nanofibrous scaffolds contributed to the presynaptic maturation via the ERK1/2-Synapsin I signaling pathway.