讨论了PDA环境下空间数据索引技术,针对RAM存储卡特点,提出了一个格网索引思想的空间数据索引方案——"类哈希"索引,并设计了基于PDB(palm OS database)的一个实现。实验表明,在PDA环境下,基于PDB的"类哈希"索引技...讨论了PDA环境下空间数据索引技术,针对RAM存储卡特点,提出了一个格网索引思想的空间数据索引方案——"类哈希"索引,并设计了基于PDB(palm OS database)的一个实现。实验表明,在PDA环境下,基于PDB的"类哈希"索引技术,能显著加快空间数据的加载速度。展开更多
Developing highly active, low-cost and organic surfactants-free Pd-based catalysts for ethanol oxidation reaction（EOR） is now critically important for direct ethanol fuel cells. Herein, surface-clean low-doped PdB/C...Developing highly active, low-cost and organic surfactants-free Pd-based catalysts for ethanol oxidation reaction（EOR） is now critically important for direct ethanol fuel cells. Herein, surface-clean low-doped PdB/C catalysts（typically ca. 1.5 at% of B） are successfully prepared in an aqueous condition without adding any organic surfactants. TEM characterization shows that as-prepared low-doped Pd B nanoparticles are evenly distributed on carbon support. Cyclic voltommagrams of as-prepared low-doped PdB/C in 0.5 M NaOH ＋ 1 M C2H5OH indicate that its onset oxidation potential of ethanol is ca. 80-120 mV more negative than that on commercial Pd/C. Meanwhile, the EOR mass activity of our home-made catalysts is up to 4018 m A·mg-1 Pd. Moreover, the durability on low-doped PdB/C catalysts is at most 2 times higher than that on commercial Pd/C. Geometric and electronic effects are adopted to understand the above mentioned enhancement of activity and durability. This work may provide a facile, low-cost and green strategy on preparing electrocatalysts toward EOR in alkaline media.展开更多
基金supported by grants from The Science Foundation for Distinguished Young Scholars of Hunan Province,China(10JJ1005)The Research Fund for The Doctoral Program of Higher Education of China(200805370002)~~
基金supported by NSFC (No.21603177)the Natural Science Foundation of Sichuan Province (No.2016JY0212)+1 种基金the Fundamental Research Funds for the Central Universities (No.2017NGJPY05)the Innovation Funds for SMU students (No. 201710656023)
文摘Developing highly active, low-cost and organic surfactants-free Pd-based catalysts for ethanol oxidation reaction（EOR） is now critically important for direct ethanol fuel cells. Herein, surface-clean low-doped PdB/C catalysts（typically ca. 1.5 at% of B） are successfully prepared in an aqueous condition without adding any organic surfactants. TEM characterization shows that as-prepared low-doped Pd B nanoparticles are evenly distributed on carbon support. Cyclic voltommagrams of as-prepared low-doped PdB/C in 0.5 M NaOH ＋ 1 M C2H5OH indicate that its onset oxidation potential of ethanol is ca. 80-120 mV more negative than that on commercial Pd/C. Meanwhile, the EOR mass activity of our home-made catalysts is up to 4018 m A·mg-1 Pd. Moreover, the durability on low-doped PdB/C catalysts is at most 2 times higher than that on commercial Pd/C. Geometric and electronic effects are adopted to understand the above mentioned enhancement of activity and durability. This work may provide a facile, low-cost and green strategy on preparing electrocatalysts toward EOR in alkaline media.
基金supported by the National Key Research and Development Program of China (2021YFA1301504)the National Natural Science Foundation of China (91953101)the Chinese Academy of Sciences Strategic Priority Research Program (XDB37040202)。
