Jian Wang,Junlian Shi,Shuai Wang,Shiguang Fan,Aijun Guo,Zongxian Wang,He Liu
While Pt-based heterogeneous catalysts have been extensively studied for cyclohexane dehydrogenation, the reaction efficiency under low temperatures remains to be resolved. In this paper, ultrafine PtPd alloy nanoparticles homogeneously anchored on nitrogen-doped carbon were synthesized and applied for cyclohexane dehydrogenation. The experimental results indicate that the synergistic effect of Pt-Pd in PtPd/CN catalyst enhances the activity and durability of the catalyst in cyclohexane dehydrogenation compared with Pt/CN and Pd/CN catalysts. The as-prepared catalyst (labeled as Pt 0.75 Pd 0.25 /CN) exhibits an excellent catalytic performance with an initial TOF value of 90.07 mmol·g −1 metal ·min −1 and a 100% H 2 purity for cyclohexane dehydrogenation at 180 °C, exceeding reported values under comparable reaction conditions. Catalyst characterizations and DFT calculations reveal that the electronic coupling effect of Pd and Pt in PtPd/CN catalyst makes the d-band center of Pt active sites closer to the Fermi level, which promotes the specific adsorption/activation of cyclohexane on Pt active sites, thus improving the catalytic performance of cyclohexane dehydrogenation. Under this guidance, the synthesized PtRu/CN and PtIr/CN alloy catalysts exhibited similar enhanced activity in cyclohexane dehydrogenation. This work provides insights into the rational design of efficient and stable Pt-based bimetallic catalysts for cyclohexane dehydrogenation.
The development of efficient and durable electrocatalysts is essential for the practical application of fuel cells. Metal-support interaction (MSI) is an important concept in heterogeneous catalysis, which can construct the structure of catalyst and improve the reaction activity and stability of catalyst. Based on this, a simple and efficient method is innovatively proposed to synthesize coral-like special structure catalyst by utilizing the crush capacity of high energy γ-rays and the structure-induced effect of MSI between PtPd alloy and nitrogen-doped graphene quantum dots. The electrocatalyst demonstrates superior long-term durability due to the structure of catalyst is not easy to collapse under suitable MSI. Meanwhile, the unique coral-like structure provides a larger contact area, abundant mass transfer channels, and full exposure of active sites, which are advantageous to improve electrocatalytic activity. The oxygen reduction reaction performance of optimal catalyst (NGQDs 140 -PtPd) was far superior to that of the commercial 20% Pt/C in alkaline medium, including onset potential (959 mV), half-wave potential (860 mV) and stability (the residual current density was 86.5% after long-term stability test). Therefore, coral-like shaped catalysts are expected to become a member of high-efficiency oxygen reduction catalysts in practical applications.
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