Jianbing Zhu

Enhanced activity of Pt nano-crystals supported on a novel TiO2@N-doped C nano-composite for methanol oxidation reaction

The development of advanced support materials displays the potential for both reducing the cost and simultaneously increasing the activity of catalysts. In the current work, a novel N-doped carbon coated hydrophilic titanium dioxide (TiO2@N-doped C) nano-composite, constructed by the procedure of an in situ polymerization and subsequent pyrolysis, was utilized to support Pt nano-crystals for the methanol oxidation reaction (MOR). The as-prepared Pt/TiO2@N-doped C catalyst generated 1.74-fold higher activity, 2.08-fold higher stability and much better resistance to CO poisoning than a commercial state-of-the-art Pt/C catalyst. The enhanced catalytic performance was ascribed to the improved CO tolerance and the catalyst–support interaction due to the utilization of the TiO2@N-doped C nano-composite, which not only provides rich active –OH groups to promote CO oxidation via the bifunctional mechanism, but also modifies the electronic structure of the Pt NPs to improve the intrinsic kinetics of MOR. The as-developed TiO2@N-doped C nano-composite is a highly promising catalyst support material for use in fuel cell technology.

Enhanced Catalytic Performance of Composition‐Tunable PtCu Nanowire Networks for Methanol Electrooxidation

Ultrathin PtCux (x=1, 2 and 3) nanowire networks (NWMs) with controllable compositions were successfully synthesized by using Triton X‐100 as the structure‐directing agent in aqueous solution. The as‐prepared PtCux nanocrystals were characterized by transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, cyclic voltammetry, and chronoamperometry. The results show that electrocatalytic performance of the PtCux NWNs towards the methanol oxidation reaction is enhanced relative to that of commercial Pt/C catalysts. Moreover, if the initial atomic ratio of Pt/Cu is 1:2, the corresponding PtCu2 NWNs catalyst generates mass activity that is 3.77‐fold higher and specific activity that is 2.71‐fold higher than the corresponding properties of commercial Pt/C catalysts. The enhanced activity can be attributed to a unique structure and a modified electronic effect.

Rapid synthesis of a PtRu nano-sponge with different surface compositions and performance evaluation for methanol electrooxidation

A rapid strategy to synthesize a highly active PtRu alloy nano-sponge catalyst system for methanol electro-oxidation is presented. The greatly increased Pt utilization, anti-CO poisoning ability and electronic effect resulting from the porous nano-sponge structure could account for the performance improvement.

Growth mechanism and active site probing of Fe3C@N-doped carbon nanotubes/C catalysts: guidance for building highly efficient oxygen reduction electrocatalysts

Non-platinum (NP) electrocatalysts with high activity and durability for oxygen reduction reactions (ORR) are required for fuel cells and other renewable systems. To avoid trial-and-error methods and achieve the rational design and synthesis of efficient NP catalysts, in-depth knowledge of the formation/growth mechanism of nanocatalysts and the origin of active sites is highly desirable. Here, we report a new class of NP catalysts with a novel structure of Fe3C encapsulated in N-doped carbon nanotubes/C. We study the formation mechanism of the nanostructure to pave the way for controlled fabrication of high-performance NP catalysts. The encapsulation of iron into carbon occurs during the first step of CNT growth and the surface functional groups on carbon black are identified as being essential for forming CNTs. The catalyst shows ultrahigh catalytic performance in both acid and alkaline media. We also examine the structure–performance dependency. The catalytic performance is highly dependent on the nanostructure and the encapsulation of Fe3C. Fe affects the catalytic performance through electronic effects rather than by directly participating in the active sites. This result is confirmed by DFT calculations, which show an increase in the density of states and a reduction in the local work function, XPS studies, and electrochemical measurements. The likelihood of N participating in the active sites is low because the catalytic performance does not depend on pyridinic and graphitic N.

Significantly enhanced oxygen reduction reaction performance of N-doped carbon by heterogeneous sulfur incorporation: synergistic effect between the two dopants in metal-free catalysts

Developing highly active non-noble metal oxygen reduction reaction (ORR) catalysts is crucial for a variety of renewable energy applications including fuel cells and metal–air batteries. Heteroatom doped carbon materials, known as metal-free catalysts, show potential applications in the ORR, and may be promising replacement candidates for expensive, scarce platinum catalysts. Despite the inspiring progress made, the performance of the current metal-free carbon catalysts is still far from satisfactory for large-scale applications. Herein, we introduce an effective and robust ORR catalyst based on N, S co-doped carbon materials with abundant surface active sites. Electrochemical results indicate that the incorporation of sulfur into nitrogen-doped carbon (S-NCx) can dramatically improve the stability of the catalyst by improving the selectivity of O2 electro-reduction to H2O. Density functional theory calculations reveal that sulfur doping lowers the energy barrier of O2(ads) hydrogenation to form OOH(ads), thus leading to enhanced intrinsic activity. In particular, the correlation between ORR activity and nitrogen and sulfur species in these materials is studied in-depth, and it is found the ORR performance of S-NCx catalysts is significantly affected by pyridinic N and C–S–C contents.

Pt–Pb hollow sphere networks: self-sacrifice-templating method and enhanced activity for formic acid electrooxidation

We demonstrate a self-sacrifice-templating method to synthesize Pt–Pb hollow-sphere networks, in which the hollow-spheres arise from the self-sacrifice of in situ formed Pb nanoclusters without the use of a pre-existing template and the networks originate from the diffusion-limited aggregation process. Of particular interest is that the as-prepared Pt–Pb catalyst shows a significantly enhanced activity for formic acid electrooxidation.

Preparation of Pt hollow nanotubes with adjustable diameters for methanol electrooxidation

Pt hollow nanotubes (Pt HNTs) with adjustable diameters as methanol oxidation electrocatalysts were synthesized through a galvanic replacement method, in which Ag nanowires with variable diameters obtained under controllable microwave irradiation conditions were used as the sacrificial templates. The Pt HNTs with a diameter of 100 nm (Pt-100) exhibited the highest catalytic activity, which was 1.6 times the state-of-the-art commercial Pt black, showing the advantage of hollow tube nanostructure over nanoparticle structure in electrocatalysis for the methanol oxidation reaction (MOR). Dependence of electrocatalytic activity on Pt HNT diameter reflects the Pt utilization effect in the geometrical view.

Observations of 2000 DP107 in NAOC: rotation period and reflectance spectrum

Abstract Photometric observations of a Near-Earth-Asteroid (NEA) 2000 DP107 were made on four successive nights during October 2000, 1.4–4.7 with the 0.6-m/0.9-m Schmidt telescope of National Astronomical Observatories, CAS (NAOC). The derived rotation period of 0.1156 day was consistent with that obtained by Pravec et al. (IAU Circular No. 7504, 2000). In addition, the relative reflectance spectrum of the asteroid covering 0.35– 0.9 μm was obtained with the NAOC 2.16-m telescope adopting a low-resolution grating ( 10 A /pix) on October 2, 2000, which revealed that 2000 DP107 is an M-type asteroid.

Promotion of Mesoporous Vanadium Carbide Incorporated on Resorcinol–Formaldehyde Resin Carbon Composites with High‐Surface‐Areas on Platinum Catalysts for Methanol Electrooxidation

Vanadium carbide incorporated on resorcinol–formaldehyde resin carbon (V8C7@RFC) was synthesized as a novel mesoporous catalyst‐support material by pyrolysis of the resorcinol–formaldehyde resin and NaVO3 mixture. The material’s BET surface area was 564 m2 g−1 and thus much higher than that of 389 m2 g−1 for the carbon powders yielded by resin carbonation. Physical characterization revealed that the supporting material possesses a mesoporous structure and Pt nanoparticles are homogeneously dispersed on the V8C7@RFC surface. Electrochemical measurements demonstrated that the V8C7‐modified Pt catalyst exhibits a negative shift of over 100 mV in the onset potential for COads electrooxidation and a dramatically enhanced activity in methanol oxidation reaction. The enhancement was mainly attributed to the electronic effect between Pt and V8C7 and the mesoporous structure providing ideal anchor sites for Pt dispersion.