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Abstract: ZnO and TiO2 single-crystalline nanowires (SCNWs) are considered to be ideal materials for the photoanode of dye-sensitized solar cells (DSSCs) due to their superior property of electron transfer, however, a direct comparison between the above two systems has not been made. In the present work, ZnO and TiO2 SCNWs were synthesized directly on conductive glasses by wet chemical methods, and their sizes were kept identical. After being sensitized by N3 dye, the two kinds of nanowires were employed as photoanodes for assembling DSSCs. Comparative studies show that, although TiO2 SCNWs adsorb less dye molecules, they could effectively retard charge recombination and achieve longer electron lifetime than ZnO SCNWs; as a result, the DSSCs composed of TiO2 SCNWs exhibit higher performance than those of ZnO SCNWs. [Copyright &y& Elsevier]

Lattice trapping is an important aspect in accurately understanding the fracture behaviors of nanomaterials. Employing molecular dynamics simulations, we studied the lattice trapping of nanocracks in both single-crystal and polycrystalline graphene. Different crack-dislocation and crack-grain boundary configurations were constructed and investigated. It is found that cracks in single-crystal graphene exhibit negligible lattice trapping, with or without the presence of dislocations. On the other hand, lattice trapping in polycrystalline graphene may vary greatly and is shown to be directly correlated to the tensile strength of grain boundary. Moreover, we showed that unique dislocation-independent traction-separation behaviors, which are not affected by the presence of dislocations, exist for cracks in single-crystal graphene. The traction-separation relation was then fitted to a cohesive zone model to demonstrate the possibility of bridging atomistic modeling with large-scale numerical simulations. Our findings provide critical hints for atomistic-informed multiscale modeling of fracture of two-dimensional materials. [ABSTRACT FROM AUTHOR]

Both increasing demand for ultrasensitive detection in the scientific community and significant new breakthroughs in materials science field have inspired and promoted the development of new-generation multifunctional plasmonic sensing platforms by adopting promising plasmonic nanomaterials. Recently, high-quality surface plasmon resonance (SPR) sensors, assisted by two dimensional (2D) nanomaterials including 2D van der Waals (vdWs) materials (such as graphene/graphene oxide, transition metal dichalcogenides (TMDs), phosphorene, antimonene, tellurene, MXenes, and metal oxides), 2D metal−organic frameworks (MOFs), 2D hyperbolic metamaterials (HMMs), and 2D optical metasurfaces, have emerged as a class of novel plasmonic sensing platforms that show unprecedented detection sensitivity and impressive performance. This review of recent progress in 2D nanomaterials-enhanced SPR platforms will highlight their compelling plasmonic enhancement features, working mechanisms, and design methodologies, as well as discuss illustrative practical applications. Hence, it is of great importance to describe the latest research progress in 2D nanomaterials-enhanced SPR sensing cases. In this review, we present some concepts of SPR enhanced by 2D nanomaterials, including the basic principles of SPR, signal modulation approaches, and working enhancement mechanisms for various 2D materials-enhanced SPR systems. In addition, we also demonstrate a detailed categorization of 2D nanomaterials-enhanced SPR sensing platforms and comment on their ability to realize ultrasensitive SPR detection. Finally, we conclude with future perspectives for exploring a new generation of 2D nanomaterials-based sensors. [ABSTRACT FROM AUTHOR]

• An excellent bi-color probe named PEG@ReSe 2 nanosheets was prepared. • The nanoprobe exhibited strong two-photon features under a low power excitation. • The nanoprobe showed strong photostability, low cytotoxicity, enabling to perform in vivo bioimaging in cancer cells. Recently two-dimensional (2D) nanomaterials-mediated photothermal therapy (PTT) has become an important tool for treating cancer. However, visually monitoring the localization of nanoagents in cancer cells remains a key challenge. Herein, exploring high photostability, and high biocompatibility probes for monitoring PTT are still highly desirable. In this study, a novel optical probe named PEG@ReSe 2 nanosheets (polyethylene glycol, PEG; rhenium diselenide, ReSe 2) was prepared and employed to perform in vivo two-photon imaging for monitoring PTT in esophageal cancer cells. Under the illumination of a near-infrared (NIR) femtosecond laser at 820 nm with the output power as low as 5 mW, the PEG@ReSe 2 nanosheets showed significant two-photon features, producing a significant photoluminescence emission band at 637 nm. In addition, the prepared PEG@ReSe 2 nanosheets exhibited high resistance to photobleaching. Also, the PEG@ReSe 2 nanosheets showed low cytotoxicity for cancer cells, providing a high viability of more than 90%. More importantly, the PEG@ReSe 2 nanosheets could enter cancer cells and work as a two-photon probe for visually displaying the PTT process. After 12 h incubation, the PEG@ReSe 2 nanosheets produced strong two-photon signals in KYSE150 cancer cells, enabling them to perform in vivo bi-channel bioimaging. In light of its photothermal effects, the PEG@ReSe 2 nanosheets also could serve as a sensor for monitoring PTT under low-power infrared laser irradiation. This study suggests that, the PEG@ReSe 2 nanosheets could serve as a superior two-photon biosensor for monitoring the PTT process in cancer nanomedicine. [ABSTRACT FROM AUTHOR]

Ultrasensitive detection of chemicals and biological analytes in trace or single molecular level is highly desirable in both scientific and technological fields, e.g. , analytical chemistry, life science, materials science, biomedical diagnostics, and forensic science, etc . With high sensitivity, high specificity, narrow line-widths, and multiplexed non-destructive testing capabilities, surface enhanced Raman scattering (SERS)-based sensing is the most promising approach to monitor targeted analytes in the vicinity of nanostructured surface. An insight into the recent advances of SERS-based ultrasensitive sensing platform can provide an effective reference guideline to develop an optimal detection approach for arising real-world applications. Many SERS-based review articles mainly focus on the fundamental theory of SERS, nanostructured plasmonic SERS sensors, and single molecule SERS detection. However, no comprehensive review article targeting SERS-based ultrasensitive detection strategies, their working mechanisms and illustrative practical applications has been reported yet. Hence, it is important to project the latest SERS-based ultrasensitive detection research in a review, which will present a reference guideline to develop an optimal detection approach for specific detection or monitoring of analytes in highly diluted solutions. We present a systematic classification and discussion on the recent multiple strategies to achieve ultra-high SERS detection sensitivity. We also outline a detailed analysis on the up-to-date applications in vitro and in vivo . Finally, we also discuss a new trend in SERS-based ultrasensitive sensing applications. [ABSTRACT FROM AUTHOR]

In this work, self-supported NiTe nanosheets were prepared via one-step microwave method. XRD and XPS spectroscopy showed the successful synthesis of NiTe material in the hexagonal crystal system. SEM and EDS were used to identify the microscopic morphology and composition of NiTe on nickel foam (NF). The electrode demonstrated specific capacitance (Cs) of 808.9 F g−1 and ultra-long cycle life of 60,000 cycles. In addition, a solid-state asymmetric supercapacitor consisted of NiTe@NF electrode as cathode material and demonstrated the largest energy density and power density of 94.4 μWh cm−2 and 7801.8 μW cm−2, respectively, and the specific capacitance remained 83.3% after 20,000 cycles. Moreover, the as-obtained NiTe@NF catalyst also displayed an excellent catalytic activity for oxygen evolution reaction (OER), which achieved an ultra-low overpotential of 199.5 mV at 10 mA cm−2. [Display omitted] • The NiTe nanosheet offered outstanding specific capacitance of 808.9 F g−1. • Superior durability of 91.4% retention during 60,000 cycles. • The NiTe@NF electrode delivered a small Tafel slope and a low overpotential. • Self-supporting NiTe nanosheets were prepared within 150 s via a microwave method. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) light-mediated two-photon microscopy has become a promising tool for early cancer therapy. However, exploring novel two-photon probe with high biocompatibility and high photostability to resist photobleaching, remains a key challenge for performing in vivo bioimaging. Herein, a novel two-photon luminescence (TPL) probe named two-dimensional rhenium disulfide (ReS 2) nanosheets was firstly reported for performing intracellular bioimaging. Under the illumination of low power NIR femtosecond laser, the prepared ReS 2 nanosheets exhibited strong NIR photon absorption, generating a strong TPL band at 640 nm. In addition, in vitro TPL imaging showed that, ReS 2 nanosheets possessed excellent photostability, enabling to resist photobleaching. More importantly, ReS 2 nanosheets functionalized by polyethylene glycol (PEG) showed negligible cytotoxicity, suitable to perform intracellular TPL imaging. With prolonged 6-hour incubation time, the TPL intensity of PEG-ReS 2 nanosheets in three kinds of living cells such as esophageal cancer cells (KYSE150), pancreatic cancer cells (4T1) and HeLa cells, were significantly enhanced by almost 4, 11, and 17 times, respectively. In view of their photothermal effects, the PEG-ReS 2 nanosheets could work as an excellent TPL probe for monitoring photothermal therapy and evaluating therapeutic outcomes. This study highlights great potential of PEG-ReS 2 nanosheets as a TPL biosensor for intracellular optical imaging and cancer therapy. • A novel TPL nanoprobe named 2D rhenium disulfide (ReS 2) nanosheets was prepared. • The proposed probe showed excellent photostability, enabling to resist photobleaching. • The proposed probe exhibited negligible cytotoxicity, enabling to perform in vivo bioimaging. [ABSTRACT FROM AUTHOR]

The development of high-efficient and cost-effective electrocatalysts is crucial to remove nitrate pollutant in wastewater. Herein, we design and prepare mesoporous Co-doped Cu 2 (OH) 2 CO 3 malachite nanosheets as an electrocatalyst toward highly efficient nitrate reduction using a facile CO 2 bubble-assisted coprecipitation synthesis. The electrocatalytic performance is subject to the Co/Cu ratio of this malachite. Remarkably, compared with the pristine monometal Cu or Co-based electrocatalyst, the optimal electrocatalyst, 0.3Co@Cu 2 (OH) 2 CO 3 , displays fast and highly efficient removal capacity of nitrate with an impressive high total nitrogen (TN) removal of 8628.99 mg N g−1 CoCu (398.79 mg N g cat −1 h−1), N 2 selectivity of 97.11% as well as negligible nitrite product at 100 mg L−1 NO 3 --N and 2000 mg L−1 Cl- neutral electrolyte. Above all, high total nitrogen removal efficiency (81.92%) and chemical oxygen demand (73.74%) in actual wastewater. Its excellent electrocatalytic performance is achieved by regulating the electronic structure and the adsorption/desorption of the intermediate. This study discovers a new type of electrode materials for nitrate removal in wastewater. [Display omitted] • Mesoporous Co-doped Cu 2 (OH) 2 CO 3 nanosheets have been synthesized by an in-situ CO 2 template. • 0.3@Cu 2 (OH) 2 CO 3 catalyst has excellent NO 3 reduction performance and long-term durability. • 0.3@Cu 2 (OH) 2 CO 3 catalyst displays fast and impressive high total nitrogen (TN) removal. • DFT results show its unique structure and composition improve electrocatalytic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Our approach, for the first time, using melamine nitrate as precursor, sodium borohydride as B source and Na source, by controlling the heating rate and thermal post-treatment, B/Na co-doped porous carbon nitride nanosheets were successfully prepared. • The as-synthesized B/Na co-doped porous g-C 3 N 4 nanosheets obtained wonderful photocatalytic hydrogen generation properties, AQE value of 9.39% under the radiation of 430 nm wavelength, and high-efficiency photocatalytic removal of TC performance. • The energy saving LED is used as the light source for hydrogen production. g-C 3 N 4 has attracted wide concern owing to its function of photocatalytic degradation of pollutants and H 2 production. However, the bulk carbon nitride (BCN) has many shortcomings, such as poor light absorption ability, short life of photogenerated electrons and few reactive sites. In this study, element doping and morphology control strategies were used to enhance their activity. B/Na co-doped porous carbon nitride nanosheets (PNCN-BNa-3) were successfully prepared by controlling the heating rate and thermal post-treatment using melamine nitrate as precursor, sodium borohydride as B source and Na source. Thanks to the synergistic effect of the porous nanosheets structure and B/Na co-doped, the B/Na co-doped porous g-C 3 N 4 nanosheets obtained wonderful photocatalytic hydrogen generation properties (5971.51 μmol·g−1·h−1), AQE value of 9.39% under the radiation of 430 nm wavelength, and high-efficiency photocatalytic removal of TC performance (the removal efficiency reached 78.39% in 30 min). This provides a new idea for the preparation of semiconductor photocatalysts with good property. [ABSTRACT FROM AUTHOR]

Hydrogenation is a viable approach in transforming two-dimensional (2D) nanosheets into three-dimensional (3D) nanoarchitectures. The present work reported self-folding of 2D graphene into 3D graphene Miura origami assisted by hydrogenation, and studied its Poisson's ratio under external strain using molecular dynamics simulation and continuum modeling. It was found that the graphene Miura origami possesses negative Poisson's ratio, being largely insensitive to the chirality of the folding creases and side lengths of the constituting parallelograms. We further demonstrated the good agreement of Poisson's ratio between the continuum prediction and MD simulation, and identified the origin of their deviation as localized stress concentration at the quad-junction of the graphene Miura origami. The present study provides insights into designing novel 3D nanoarchitectures of programmable functionalities from 2D nanomaterials. • Self-folding of graphene into graphene Miura origami was achieved by selective hydrogenation. • Poisson's ratio behavior was systematically studied by molecular dynamics simulation and continuum modeling. • Effects of chirality of folding, side lengths of constituting parallelograms, and local deformation were clarified. [ABSTRACT FROM AUTHOR]