N-doped active carbon (N-AC) has been synthesized via heat treatment of a mixture consisting of dicyandiamide as the nitrogen source and commercial active carbon as the precursor. This material is especially adapted for anchoring ultrafine Pd nanoparticles by a very clean strategy using H2 as the reductant. The physicochemical properties of materials were investigated by powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results reveal that the variation of the treatment temperature can assist the tuning of the content of N and the dispersion of Pd on xN-AC, by which Pd nanoparticles with a narrow size distribution centered at around 1.8 nm can be obtained. These robust catalysts show very high catalytic activity for the aromatic ring hydrogenation of acidic substrates, such as electron-deficient benzoic acid or electron-rich phenol, under mild conditions in aqueous media. Excellent catalytic results (9.2 times higher activity in comparison to non-doped catalyst for benzoic acid hydrogenation), high stability and easy recyclability of the catalyst were achieved. The strong interaction between the pyridinic nitrogen group and Pd species will lower the reducibility of the Pd species and result in the formation of relatively electron-deficient and ultra-small sized Pd clusters, thus leading to high hydrogenation activity.
Libo Zhu,Tiantian Wu,Shuo Bi,Changchun Ke,Chang Chen,Han Tian,Fantao Kong,Xiangzhi Cui,Jianlin Shi
The electrode mass transport limitation during borohydride oxidation reaction (BOR) involving three-phase interfaces greatly deteriorates the performance and energy efficiency of direct sodium borohydride fuel cells (DBFCs). Here we develope a hierarchical structure electrode (HSE) strategy via dispersing Pd clusters on needle-structured CoP-O nanoarrays in situ grown on optimized macro-porous nickel foam (NF), to enhance the solution/gas transport, catalyst utilization and across electrode conductivity, and meanwhile to regulate the OH – -enrichment local environments at the anode of DBFC. The fabricated Pd@CoP-O/NF HSE exhibits excellent BOR catalytic activity featuring a rather low overpotential of 433 mV at 1 A cm −2 and an electron transfer number up to 7.8, and particularly an extra-high power density of 1.23 W cm −2 under O 2 conditions. The watt-level power density of DBFCs is achieved by the adsorption regulations of H*/OH – species on the catalyst and the effective separation and dissipation of bubbles from electrode, which provides an alternative but highly promising pathway for DBFC applications.
危险品化学品经营许可证（带存储）