Electrodeposition of vertically standing Ag nanoplates and nanowires on transparent conductive electrode using porous anodic aluminum oxide template

Mechanism Understanding for Size Regulation of Silver Nanowires Mediated by Halogen Ions

The controllable preparation of silver nanowires (AgNWs) with a high aspect ratio is key for enabling their applications on a large scale. Herein, the aspect ratio regulation of AgNWs mediated by halogen ion composition in ethylene glycol system was systematically investigated and the size evolution mechanism is elaborately understood. The co-addition of Br- and Cl- results in AgNWs with the highest aspect ratio of 1031. The surface physicochemical analysis of AgNWs and the density functional theory calculations indicate that the co-addition of Br- and Cl- contributes to the much-enhanced preferential growth of the Ag(111) crystal plane. At the same time, when Cl- and Br- coexist in the solution, the growth of the Ag(100) crystal plane on the AgNWs was restrained compared with that in the single Cl- system. Resultantly, the enhanced growth of Ag(111) and the inhibited growth of Ag(100) contribute to the formation of AgNWs with a higher aspect ratio in the Cl-Br mixed solution. The results can provide new insights for understanding the morphology and size evolution during the AgNWs preparation in ethylene glycol system.

Assembly of long silver nanowires into highly aligned structure to achieve uniform "Hot Spots" for Surface-enhanced Raman scattering detection

Silver nanowires (AgNWs) as a promising surface-enhanced Raman spectroscopy (SERS) substrate could be used in the analytical science due to its high sensitivity. However, it is difficult for the randomly-distributed silver nanowires to offer uniform "hot spots" to achieve the SERS signal reproducibility of small molecules detection. Herein, the evaporation-induced aggregation had been used to assemble long silver nanowires into highly aligned structure to achieve uniform "hot spots" for SERS detection. The normal glass slide with well-aligned silver nanowires could act as a high sensitivity and excellent reproducibility SERS substrate to provide a versatile platform for detecting analytes. Rhodamine 6G (R6G) is used to evaluate the sensitivity and reproducibility of these AgNWs SERS substrates. Even the low concentration of the R6G was 10^-10 mol/L, the SERS features of R6G could be still observed clearly, and the uniform distribution of enhancement factor (EF) was higher than 0.8 × 10⁴ accounting for about 75 % in the observed mapping area. Moreover, the relative standard deviation (RSD) of SERS intensity at the band of 610 cm^-1 was used to estimate the signal reproducibility, and the calculated RSD value of aligned AgNWs substrate was about 3.6%, which was much higher than that of the randomly distributed AgNWs (26.8%) because of the highly aligned structure of silver nanowires with abundant and uniform inherent "hot spots". In addition, potential SERS detection of other small molecule, e.g. melamine was also demonstrated in the micromolar range.

High-density Ag nanosheets for selective electrochemical CO2 reduction to CO

To increase the specific surface area, high-density (i.e. number per unit area) Ag nanosheets (ANS) with large electrochemically active surface area and rich edge active sites over Ag plates were synthesized via a facile electrodeposition approach in a double electrode system at a constant current of -1 mA for 1800 s. By adjusting the concentration of H₃BO₃ (0.5 M, 0.1 M and 0.05 M), which is used to control the growth direction of ANS, ANS-20, -50, -350 were obtained with varying thickness of 20 nm, 50 nm, and 350 nm, respectively. Notably, ANS-20 showed a remarkable current density of -6.48 mA cm^-2 at -0.9 V versus the reversible hydrogen electrode (RHE), which is almost 1.6 and 2.4 times as high as those of ANS-50 and -350, respectively. Furthermore, ANS-20 exhibits the best CO selectivity of 91.2% at -0.8 V versus RHE, while the other two give 84.6% and 77.9% at the same potential. The excellent performance of ANS-20 is attributed to its rich edge active sites and large electrochemically active surface area (ECSA).

The toolbox of porous anodic aluminum oxide–based nanocomposites: from preparation to application

Anodic aluminum oxide (AAO) templates have been intensively investigated during the past decades and have meanwhile been widely applied through both sacrificial and non-sacrificial pathways. In numerous non-sacrificial applications, the AAO membrane is maintained as part of the obtained composite materials; hence, the template structure and topography determine to a great extent the potential applications. Through-hole isotropic AAO features nanochannels that promote transfer of matter, while anisotropic AAO with barrier layer exhibits nanocavities suitable as independent and homogenous containers. By combining the two kinds of AAO membranes with diverse organic and inorganic materials through physical interactions or chemical bonds, AAO composites are designed and applied in versatile fields such as catalysis, drug release platform, separation membrane, optical appliances, sensors, cell culture, energy, and electronic devices. Therefore, within this review, a perspective on exhilarating prospect for complementary advancement on AAO composites both in preparation and application is provided.

Synthesis and Applications of Silver Nanowires for Transparent Conductive Films

Flexible transparent conductive electrodes (TCEs) are widely applied in flexible electronic devices. Among these electrodes, silver (Ag) nanowires (NWs) have gained considerable interests due to their excellent electrical and optical performances. Ag NWs with a one-dimensional nanostructure have unique characteristics from those of bulk Ag. In past 10 years, researchers have proposed various synthesis methods of Ag NWs, such as ultraviolet irradiation, template method, polyol method, etc. These methods are discussed and summarized in this review, and we conclude that the advantages of the polyol method are the most obvious. This review also provides a more comprehensive description of the polyol method for the synthesis of Ag NWs, and the synthetic factors including AgNO3 concentration, addition of other metal salts and polyvinyl pyrrolidone are thoroughly elaborated. Furthermore, several problems in the fabrication of Ag NWs-based TCEs and related devices are reviewed. The prospects for applications of Ag NWs-based TCE in solar cells, electroluminescence, electrochromic devices, flexible energy storage equipment, thin-film heaters and stretchable devices are discussed and summarized in detail.