Silver Nanorings: New Generation of Transparent Conductive Films.

Low-cost and high yield silver nanorings with the uniform ring diameter of 15±5 µm and thickness of 120±20 nm were synthesized via a simple solvothermal method. Based on our knowledge, this is the first time that a solvothermal method is used to prepare silver nanorings. Herein, by using ammonium salts as additive salts in the presence of pressure (150 kPa) inside the reactor, the reproducibility and yield of nanorings increased. The prepared silver nanorings easily dispersed in ethanol and have been coated by spray method on PET substrate to make flexible transparent conductive films (TCF). The film based on nanorings was shown better opto-electrical properties (higher transparency with lower haze) in comparison with nanowires with higher aspect ratio and lower thickness, at the same sheet resistance (Rs). These results introduce silver nanorings as outstanding candidates for optoelectronics applications.

Movement-reactor oven and wire mesh filter for large-scale solvothermal preparation and purification of silver nanowires with high uniformity in length and diameter for the fabrication of low and high haze transparent conductive films.

Conventional polyol synthesis has been widely used for the preparation of metal nanowires with different aspect ratios. However, its main drawback is that it is difficult to control the reaction parameters for the shape-controlled synthesis of metal nanowires. Although with the solvothermal method the shape control and growth rate improve, but on a large scale, there are still some challenges such as high reactor weight, long processing time and non-heat uniformity in different positions of the oven. In addition, the purification of nanowires on a large scale is another challenge in this area. Herein, we report the use of a movement reactor oven with the ability to rotate the reactors, and high heat conductive, light-weight reactors for the large-scale preparation of silver nanowires with highly uniform lengths and diameters. The uniformity of the length and diameter of the nanowires using the movement reactor oven in comparison with that using the fixed-reactor oven significantly improved. Furthermore, the amount of silver nanowires increased by 20 times using the new reactor in comparison with the standard Teflon-lined stainless steel reactor for the same reaction time. Reactor rotation, as a new parameter to adjust the final product, was introduced. The synthesized nanowires with and without rotation showed the same morphology and electrical conductivity. For the purification step, first, a new angular filtration method using a wire mesh filter was applied to separate the solvents and ionic impurities, and then by using the same filter based on tangential flow, the nanowires were separated from nanoparticles. Finally, uniform and coffee ring-free transparent conductive films (TCFs) with different haze values were fabricated by coating the formulated silver nanowire ink containing a mixture of green solvents. The fabricated films can be potentially used in a wide range of applications.

H2 oxidation versus organic substrate oxidation in non-heme iron mediated reactions with H2O2.

Herein we show that species generated upon reaction of α-[Fe(CF3SO3)2(BPMCN)] (BPMCN = N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane) with H2O2 (putatively [Fe(V)(O)(OH)(BPMCN)]) is able to efficiently oxidize H2 to H2O even in the presence of organic substrates, while species formed in the presence of acetic acid (putatively [Fe(V)(O)(OAc)(BPMCN)]) prefer organic substrate oxidation over H2 activation. Mechanistic implications have been analysed with the aid of computational methods.