Recently, Li Yue, a researcher at the Institute of Micro-Nano Technology and Devices, Institute of Solid State Physics, Institute of Solid State Physics, Chinese Academy of Sciences, made new progress in the control of porous gold-silver-platinum (AuAgPt) alloy nanomaterials and their methanol catalysis research. The relevant research results are published in Journal of Materials Chemistry A (J. Mater. Chem. A, DOI: 10.1039/c8ta04087g).
In recent years, with the rapid development of the economy, China's demand for energy is increasing. Fossil energy, as the most important energy consumed by the world, brings us convenience and also causes serious pollution to the global environment. Therefore, development Clean energy, which can replace fossil energy, is becoming more and more important. Fuel cell is a device that can directly convert the chemical energy in fuel and oxidant into electric energy. It is the fourth after hydropower, firepower and atomic power generation. It has the advantages of energy saving, high conversion efficiency and close to zero emission. It has become an important way to solve energy and environmental problems. Among them, methanol fuel cells are widely used because of their high efficiency and environmental friendliness. Portable equipment. Compared to hydrogen energy, methanol is a cheaper liquid fuel, easy to store, easy to transport, and has a higher theoretical energy density. Therefore, methanol fuel cells have very good application potential in the field of new energy.
At present, the catalysts for methanol fuel cells are mainly made of platinum nanomaterials. However, in the preparation process, traditional platinum nanomaterials may cause side effects such as poisoning and precipitation, which gradually reduce the effective area activity and mass activity of platinum nanocatalysts, which seriously affects The service life of methanol fuel cells. In addition, the metal platinum required for the preparation of platinum nanomaterials has low storage capacity, high cost and high cost, which is not conducive to large-scale commercial application of batteries. In order to improve the catalytic activity and stability of methanol fuel cell catalysts. Lithium, platinum and platinum-based nanocatalysts with different structures have been prepared by various methods, such as: platinum nanoparticles with high-index crystal faces, hollow platinum-palladium alloys, platinum-nickel alloys, silver-platinum alloys, etc., but these materials Most of the preparation methods are complicated, the reaction cycle is long, and the above catalytic activity and stability problems are not well solved.
Li Yue's research group successfully prepared three-dimensional porous AuAgPt ternary alloy nanomaterial catalyst by laser induction method. They firstly reacted Au@Ag nanocube with potassium chloroplatinate to obtain Au@AgPt nanocube (Au@AgPt NCs). The Au@AgPt nanocube is laser irradiated by a 670~700 volt laser to rapidly melt the Au@AgPt nanocube into solid AuAgPt alloy nanospheres (solid AuAgPt NSs), and then the solid AuAgPt alloy is removed by chemical etching. Part of the silver in the nanospheres produces monodisperse three-dimensional porous AuAgPt ternary alloy nanospheres (Spongy AuAgPt NSs) (Fig. 1, Fig. 2). This AuAgPt ternary alloy nanosphere is not only more stable than conventional platinum. Nanomaterials, with large specific surface area and high-density active sites, are easy to adsorb reactants, can effectively improve catalytic activity, and their catalytic activity against methanol (1.62 A mgPt-1) are solid AuAgPt alloy nanospheres ( 0.35 A mgPt-1) and commercial platinum black (Pt black) (0.32 A mgPt-1) 4.6 and 5.1 times. These excellent properties are due to the porous structure of the material itself and the high-index crystal face of the material surface. grid The existence of distortion and twin boundaries. The results of this study have solved the problems of low catalytic activity, poor stability and short battery life of fuel cells.
The above research was supported by the Chinese Academy of Sciences Cross Team Project and the National Natural Science Foundation Project.
Figure 1. (a)-(b) Field emission scanning electron microscopy and transmission electron microscopy of AuAgPt ternary alloy nanospheres; (c) High-angle annular dark field-scan projection image and element distribution of AuAgPt ternary alloy nanospheres Figure (d) Line sweep element distribution; (e) X-ray diffraction pattern of AuAgPt ternary alloy nanospheres.
Figure 2. HRTEM image of AuAgPt ternary alloy nanospheres. (a) The twin boundaries and high-index crystal planes present in the particles; (b) A partial enlargement of the lattice distortion.
Figure 3. AuAgPt ternary alloy nanospheres, solid AuAgPt alloy nanospheres and platinum black methanol electrocatalytic performance test. (a) Cyclic voltammograms tested in nitrogen-saturated 0.1 M HClO4 solution; (b) at 0.1 M Methanol oxidation curve tested in HClO4 + 0.2 M methanol solution; (c) Methanol oxidation activity comparison bar chart of different catalysts; (d) Stability test comparison chart.
