image: By grinding MWCNT, Pd(acac)2, and Te powders at room temperature, Pd precursor and Te sources were dispersed on the surfaces of CNTs. By utilizing the microwave conductive properties of carboxylated multi-walled CNTs, the rapidly generated high temperature environment promotes the rapid reaction of Te and Pd to form Pd-Te NPs on CNT. Diagram credit: Yi Han. view more
Credit: ©Science China Press
This study is led by Dr. Yi Han (College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology), Prof. Jianping Lai (College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology) and Prof. Wang Lei (College of Chemistry and Molecular Engineering & College of Materials Science and Engineering, Qingdao University of Science and Technology).
Palladium tellurides (Pd-Te) have been proved to be efficient catalysts for methanol electrooxidation and ethanol electrooxidation. However, Han found that the alkaline polyols oxidation activity of Pd-Te has not been explored yet, especially the phase-controlled Pd-Te. She also noticed that the traditional synthesis methods of Pd-Te (such as solvothermal method and oil bath synthesis method) and traditional phase-controlled synthesis methods (such as the electrochemical deposition, solvothermal synthesis, and high-temperature calcination) are complicated, time-consuming, and require complicated equipment. Moreover, solvents are usually involved in these general methods, resulting in high-energy consumption and environmental pollution. Besides, due to the long-term high-temperature environment during the particle growth process, the meta-stable crystal phase transforms into a thermodynamically stable crystal phase, and small nanoparticles (NPs) agglomerate. To prevent the aggregation of particles, additives are usually used to form a protective layer, which can impede the catalytic activity of the catalyst. Therefore, Han and Lai, together with lab director Wang sought to find a more effective, simple, and rapid tellurizing method to synthesize crystalline phase-controlled Pd-Te.
The team developed a fast tellurizing method that can quickly prepare unconventional phase-controlled Pd-Te NPs on carbon nanotubes (CNTs) (i.e., PdTe/CNT, Pd20Te7/CNT) by solvent-free microwaving. In the proposed tellurizing method, only a household microwave oven is needed to synthesize the hexagonal structured PdTe/CNT and rhombohedral structured Pd20Te7/CNT (5.5 nm) in one step and 1 min. “This process is simple, fast, and requires low equipment, which has great potential for industrial production. Furthermore, considering the green sustainable chemistry, the whole process is surfactant- and solvent-free, causing it to be more energy-efficient and beneficial than traditional methods” Han says.
The researchers also found that the hexagonal structured PdTe/CNT synthesized exhibits excellent performance for glycerol oxidation reaction (GOR) and ethylene glycol oxidation reaction (EGOR). Specifically, the specific activity for GOR is 2.72 A mgPd−1, which is 1.9-fold higher than that of rhombohedral structured Pd20Te7/CNT and 2.7-fold higher than that of Pd/CNT. Meanwhile, the specific activity for EGOR is 3.65 A mgPd−1, which is 2.1 and 3.9 times higher than those of rhombohedral structured Pd20Te7/CNT and Pd/CNT. This work can provide guidance for the preparation of crystalline phase-controlled telluride catalysts via new tellurization and inspire the application of crystalline phase-controlled materials.
See the article:
Superfast tellurizing synthesis of unconventional phase-controlled small Pd-Te nanoparticles
https://doi.org/10.1007/s40843-021-1952-4
Journal
Science China Materials