Green Synthesis And Study Of Photo/electrocatalysts With Enhanced Performance

In modern world, energy and environmental issues are major challenges facing humanity. With the rapid development of industry, energy shortages and environmental pollution are common issues facing all the countries around the world.Fossil fuels are still the most frequently consumed energy currently, while fossil fuels are non-renewable energy sources. On the one hand, excessive energy depletion could be happened. On the other hand, fossil fuels emit large quantities of pollutants when usded, causing many environmental problems. Therefore, the development of new clean energy and solving current environmental issues have become an urgent need.Since 1972, Japanese scientists found that titania electrode can photolysis of water to hydrogen, the semiconductor photocatalytic technology has been considered to be an important means to solve the world’s energy crisis. Semiconductor photocatalytic technology can take advantage of abundant solar to produce hydrogen.Also, they can degrade organic pollutants and reduce carbon dioxide, which is very important for the new energy development and environmental protection.This paper is based on the mechanism of photocatalysis. The electrocatalyst and photocatalyst have been prepared via photodeposition method. And the corresponding electrocatalytic and photocatalytic properties of products were investigated.（1） The synthesis of Pt naocrystals（NCs） was carried out by using Ti O₂ nanoparticles not only as photocatalysts but also as template materials. Under the illumination of high pressure mercury lamp, the platinum nanoparticles were deposited onto the surface of the titanium dioxide by photoreduction. With increasing illumination time, platinum nanoparticles were grown into platinum nanobranches,wrapped in titanium dioxide edge ridge, thus forming cage structures. Then the above product were treated with sulfuric acid so as to etch the template completely. Platinum nanocages（Pt NCs） were prepared successfully. Characterized by high-resolution transmission electron microscopy, we found that platinum nanobranches with width of about 3 nm and separated from each other. HRTEM and fast Fourier transform confirmed that nanobranches belong to a single crystal, growing along crystalorientation of <111>. The lattice spacing was 0.23 nm, corresponding to（111） planes of face-centered cubic platinum. XRD analysis further confirmed that Pt NCs belong fcc phase. Based on the mechanism of semiconductor photocatalytic, we explored the mechanism of photocatalytic template synthesis of well-dispersed 3D Pt NCs. Pt NCs in an acidic electrolyte for methanol oxidation was tested. The results show that the mass normalised current density of Pt NCs is 4.0 times higher than that of Pt black.Besides, its stability for methanol oxidation reaction is better than the Pt black, which makes it as a promising anode catalyst for direct methanol fuel cell.（2） By using copper chloride as the precursor and titanium dioxide nanoparticles as carriers, and then Cu2O/Ti O₂ nanocomposites were prepared. The nanocomposites were characterized by XRD、 TEM 、SEM and EDS. The results show that Cu2 O particles with average diameter of 3 nm highly dispersed on the surface of Ti O₂. The results of UV-visible absorption spectroscopy showed that UV photoreduction reaction of Cu2 O was a gradual process. UV-visible diffuse reflectance spectroscopy determined that the optical response range of Cu2O/Ti O₂ nanocomposites has extended from region of ultraviolet to the region of visible light. The Cu2O/Ti O₂ nanocomposites were applied for the degradation of rhodamine B under the visible light illumination. The results indicated that the degradation rate of Cu2O/Ti O₂nanocomposites（20% copper loading） could reach 96%, which was much higher than P25（about 26%）.