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(a) Preparation of Ag NN@POM-GNSs nanocomposites, (b) SEM images of Ag NN@POM-GNSs nanocomposites, (c) TEM images of Ag NN@POM-GNSs nanocomposites, (d) ORR linearity Comparison of Scanning Voltammetry Curves, (e) Stability Test, (f) Anti-methanol Interference Performance of Ag NN@POM-GNSs Modified Electrode
At present, the advent of the global energy crisis and the increasing environmental pollution problems have forced people to pay more and more attention to the development and utilization of sustainable energy, including the storage and transformation of sustainable energy. Fuel cells and metal-air batteries are among the categories of sustainable energy utilization technologies. The catalysts for oxygen reduction reactions (ORR) at the cathodes determine the performance of batteries and determine the energy conversion efficiency and battery cost. Platinum or platinum alloys are widely used ORR electrocatalysts.
Silver, the cheapest precious metal, is only 2% platinum, but it has a certain catalytic activity and stability, but its performance is still far inferior to platinum catalysts. Considering that the electrocatalytic activity of the catalyst is closely related to the structure of nanomaterials, compared with zero-dimensional silver nanoparticles, one-dimensional silver nanowires (Ag NWs) have better electrocatalytic activity, but the effect is still not satisfactory. The main reason for the low catalytic activity of silver nanowires may be related to its low aspect ratio.
Therefore, researchers hope to prepare a two-dimensional silver nano-network structure material [Ag nanonet (NN)], which is formed by self-weaving of high aspect ratio silver wires. Due to better conductivity and thermal conductivity, this material has better catalytic activity and stability than zero-dimensional and one-dimensional materials.
And, because they are not prone to aggregation, dissolution, and Ostwald ripening, Ag NN is expected to become a new type of ORR high activity electrocatalyst. Further, in order to improve the electrocatalytic activity of the catalyst, one often chooses an ideal carbon material as a carrier. The catalyst carrier should have the following characteristics: good electronic conductivity, large specific surface area, reasonable pore structure, and excellent corrosion resistance. The appearance of graphene has brought people a gospel, which is undoubtedly the best choice for the current catalyst carrier.
At present, the preparation conditions of Ag NWs/GNSs nanocomposites reported in the literature are relatively harsh, so it is difficult to scale production. In addition, a very important aspect is that these prepared Ag NWs have a relatively low aspect ratio, so it is difficult to form Ag NN. In order to overcome this shortcoming, the research team of Zhang Guangjin of the Institute of Process Engineering of the Chinese Academy of Sciences reported that two-dimensional Ag NN@ was successfully prepared on a large scale by using polyacids (POMs) as the only reducing agent to simultaneously reduce metal ions and graphite oxide (GO). POM-GNSs nanocomposites. And through further study found that the material has a good electrocatalytic ORR performance. Although the starting potential is still more negative than the commercial platinum material, it has a larger ultimate current density and better stability, and has good resistance to methanol interference. Therefore, it is expected to realize the replacement of precious metal platinum-based catalysts, which is of great significance.
The above related research has been supported by the National Natural Science Foundation of China (No. 21071146, 51002155) and the National High-Tech Research and Development Plan (863) (No. 2012AA062903). The relevant research results were published on J. Mater. Chem. A (2013, 1, 11961–11969).
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