Research On Synthesis And Catalytic Performance Of Precious Metal Nanomaterials

In recent years,with the rapid growth of global car ownership,the problem of energy crisis,caused by excessive exploitation of fossil fuel,and the environment pollution,indirectly caused by exhaust emission,has become increasingly serious day by day.Therefore,the needs of developing clean energy and seeking ways to control water pollution have become rather urgent.Proton exchange membrane fuel cells(PEMFC)are currently known for emergency power supply,distributed power supply and vehicle power source.Among that,oxygen reduction reaction(ORR),as a cathodic reaction in the battery,has been getting a lot of attention in recent years.Pt as a noble metal and its alloy is one of the catalysts with the highest electrocatalytic activity for ORR.Owing to their rarity and huge purchasing cost,the development of Pt and its alloy is greatly.Hence,scientists can not wait to synthesize noble metal catalysts with high performance for ORR.In addition,the purification of polluted water with photocatalytic treatment is another green technology to solve energy problem and this has also been widely studied.The noble metal Au with an unique property of surface plasmon resonance(SPR)effect,can increase light harvesting efficiency capacity of photocatalytic material through payload and then improve its catalytic performance.Consider these problems,the research mainly includes the following two parts:Part 1.Synthesis of Pt9Ni wavelike nanowires(W-NWs)and its performance research in ORR properties.The synthesis of Pt9Ni@Ni-MOF-74 core-shell NWs uses the method of solvothermal route,Pt9Ni nanowires with wavy structure are successfully produced by heat treatment of formamide.The treatment for slow etching of the alloy nanowires results in the rearrangement of surface atoms,which manifests a change in the morphology of product which can increase their surface-to-volume ratio,and then show good performance of ORR.The Pt9Ni W-NWs can deliver ORR mass activity of 1.53 A mgpt-1 and specific activity of 2.85 mA cm-2[at 0.9 V versus RHE(reversible hydrogen electrode)],which is respectively 2.8-fold and 3-fold higher than that of the hollow NWs(H-NWs)of Pt9Ni prepared by the traditional fast etching with acid.Therefore,it provides a new strategy for designing effective and economic dealloying Pt-based catalysts.Part 2.Preparation of hybrid Au-Bi2WO6 hollow microspheres(labeled as Au-BiWO HMS)and the exploration in their photocatalytic properties.Au-BiWO HMS and pristine Bi2WO6 hollow microspheres(labeled as BiWO HMS)with Chemically stable and nontoxic performance were synthesized by a facile solvothermal route.We can compare the photocatalytic activity of Au-BiWO HMS samples through the degradation of Cr(?)or colorless phenol aqueous solution under visible light.Owing to the samples with relatively larger specific surface area and the successful load of Au nanoparticles on their surface,Au-BiWO HMS displayed the fast reduction of Cr(?)only in 20 min.The first-order rate constant(labeled as k)values over Au-BiWO HMS sample reached to respectively 5.12 and 71.17 times as much as that of pristine BiWO HMS and solid-state reacted Bi2W06.The typical colorless phenol aqueous solution was further selected to compare the photocatalytic activity.Within 7 hours,the k values over Au-BiWO HMS sample reach 1.21/min,which is 1.39-fold higher than that of the pristine BiWO HMS.Several comparisons showed that the photocatalytic activity of the sample has been improved.