Synthesis Of Precious Metal Nano Electrocatalysts

Noble metal nanomaterials have excellent catalytic properties,which are the research hotspot in the field of nanoscience.The excellent properties of noble metal nanomaterials are related to many factors,such as size,composition,morphology,crystal surface and surface structure.Reasonable design of the synthesis method of noble metal morphology and structure provides a reasonable research method for the design of highly efficient catalytic materials,which has very important value and significance.In this dissertation,PdH_0.33 nanodendrites,Pt₃Co zigzag nanowires and PtCo ultrafine nanowires were synthesized by effectively controlling the morphology and surface structure of noble metal-based nanocatalysts.The growth mechanism,structure and properties of PdH_0.33 nanodendrites,Pt₃Co zigzag nanowires and PtCo ultrafine nanowires were studied.The main contents are as follows:1.We report the synthesis of?-palladium hydride nanodendrites(PdH_0.33 NDs)by chemical reduction of Pd?acac?₂ in the presence of Co?acac?₃,benzoic acid,glucose monohydrate,and oleylamine at 160°C in argon atmosphere.The uniform PdH_0.33 NDs are36.3±5.0 nm in diameter and selectively expose?111?planes decorated with?221?and?331?high-indexed terraces.The PdH_0.33 NDs show a high mass activity of 0.719 A/mg_Pd at 0.9 V?vs.reversible hydrogen electrode-RHE?toward alkaline oxygen reduction reaction?ORR?,which is 3.7 and 6.3 times of that of commercial Pt/C and house-made Pd/C,respectively.Density functional theory?DFT?calculations suggest that PdH_0.33?111?should provide an appropriate oxygen adsorption energy because of tensile strain and/or electronic effect by hydride formation relative to that of Pd,thus leading to the enhanced ORR activity.This study exemplifies the possibility of using lattice H to modify the strain and/or electronic effect of metal and alloys for the optimzation of functionalities.2.The morphology of PtCo alloy was controlled by organic system to form zigzag nanowires.Because the surface structure is extremely uneven,it will also bring many unsaturated coordination atoms with high density,which is one of the reasons why the catalyst shows excellent activity in oxygen reduction.In addition,the catalyst exhibited excellent durability in basic oxygen reduction,and there was almost no loss of activity after durability.Moreover,after calcining at high temperature,the catalyst has no obvious aggregation.This also provides a new way to design catalysts for catalytic processes at high temperatures.3.For alkaline hydrogen precipitation,the effects of different metals,different morphologies,different post-treatment methods and different metal ratios on hydrogen precipitation activities were studied in detail.Through a series of experiments,Pt_0.8Co ultrafine nanowires treated with air have the activity comparable to the most advanced catalyst for alkaline hydrogen precipitation.The research results also open up a new method for the development of new electrolytic cell catalysts.