Search

For developing low Pt loading and high performance catalysts for direct methanol fuel cells, a graphitic-C3N4 quantum dots (g-C3N4 QDs) modified CNT (CNT-QDs) composite material was constructed via a π–π stacking method, in which the g-C3N4 QDs act a bridged unit between the CNTs and metal nanoparticles (NPs). Compared to conventional acid-functionalized CNTs used for supporting novel metal NPs, the CNT-QDs have less structural damage leading to their high stability. Moreover, the electrochemical test results indicate that the mass catalytic activity of the PtRu/CNT-QDs catalyst is 2.3 times higher than that of PtRu/CNT, leading to a 56.5% reduction of novel metal loading. The accelerated potential cycling tests (APCTs vs. RHE 0–1.2 V) show that the PtRu/CNT-QDs catalyst possesses 15.1% higher stability than that of the conventional acid-functionalized CNTs supported PtRu (PtRu/T-CNT) catalyst. The significantly enhanced performance obtained for the PtRu/CNT-QDs catalyst was ascribed to the homogeneous dispersion of PtRu NPs on the composite support due to its abundant Lewis acid sites for anchoring the PtRu NPs and the excellent mechanical resistance and stability of the g-C3N4/CNT composite materials in acidic and oxidative environments, as well as the strong metal–support interaction (SMSI) between the metal NPs and g-C3N4.

N-Doped carbon quantum dots (NCQDs)/multiwall-carbon nanotube (MWCNT) supports are synthesized by a one pot hydrothermal treatment process at different contents of precursor. NCQDs–MWCNT as support can be widely used in the process of electrocatalysis. In this paper, the Pt/NCQDs–MWCNT catalysts are prepared by a microwave-assisted polyol process (MAPP) method and the effects of NCQDs with different contents on the performance of Pt-based anode catalysts for methanol oxidation reaction (MOR) are systematically demonstrated. The electrochemical tests reveal that the Pt/NCQDs–MWCNT catalyst exhibits the best performance for MOR when precursor content is 3 g. In terms of the electrochemical and characterization results, the moderate content of precursor for NCQDs plays multiple roles in the electrocatalytic performance: promoting the dispersion of untreated MWCNT significantly in solution; providing the plentiful oxygen-containing groups to deposit Pt nanoparticles; and facilitating the formation of homogeneous Pt nanoparticles.

The development of highly active and durable Pt-based catalysts is an important issue for methanol electrooxidation. Research into highly efficient supports provides a feasible method to achieve such catalysts. In this paper, carbon-coated TiO2 nanowires with a unique three-dimensional network structure are prepared as a Pt-based catalyst support by the carbonization of a resorcinol–formaldehyde polymer. Physical characterization confirms that this unique structure can provide a large specific surface area, high porosity and efficient transport channels. The abundant heterogeneous interfaces between the TiO2 nanowires and carbon provide numerous Pt loading sites, which greatly improves the utilization of Pt. Strikingly, electrochemical measurements show that the as-prepared catalyst has much better activity and durability than commercial Pt/C for methanol electrooxidation. Furthermore, the single direct methanol fuel cell test demonstrates that the as-prepared catalyst has higher power density and polarization current. We attribute this excellent catalytic performance to the unique nano-network structure, the numerous Pt anchoring sites, and the synergetic effect of the different components.

In this paper, we report a rapid method to synthesize titania nanotubes as the support for a Pt-based catalyst. The titania nanotubes can be obtained during 1200 s in an ethylene glycol system by the anodization method. Pt nanoparticles were successfully deposited on a mixture of carbon and as-prepared TiO2 nanotubes by a microwave-assisted polyol process. The electrochemical results show that the electrochemically active specific surface area and the activity for methanol electrooxidation of the as-prepared catalyst are both much higher than those of the commercial Pt/C. Whether it is through the constant potential test or cycling potential test, the durability of the as-prepared catalyst is higher than that of the commercial Pt/C. Such remarkable performance is due to the strong corrosion resistance of titania, metal–support interactions and hydrogen spillover effect between Pt and titania, the better electronic conductivity, as well as the good dispersion of the Pt nanoparticles. These studies indicate that titania nanotubes are a promising catalyst support for methanol electrooxidation.

A three-dimensional (3D) structured Pt/graphene aerogel has been synthesized by a facile one-pot solvothermal process. The as-synthesized catalyst is characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and electrochemical tests. It has been found that the Pt/graphene aerogel catalyst exhibits a well-developed 3D interconnected porous graphene framework with Pt nanoparticles (NPs) decorated on the surface of the graphene aerogel. More importantly, the as-made Pt/graphene aerogel catalyst exhibits a much higher electrocatalytic activity and stability than the Pt/graphene for methanol electrooxidation. The enhancement may result from the unique 3D graphene architecture, and the efficient assembly between the Pt NPs and graphene aerogel. These outstanding properties suggest that the Pt/graphene aerogel catalyst holds tremendous potential for fuel cell applications.

Functional TS-1, partially hydrophobilized with organosilanes, was found to be more active and stable in a Pickering emulsion. In this work, TS-1 behaved simultaneously as a catalyst and solid emulsifier favoring the cyclohexanone ammoximation reaction in organic solvent-free conditions. The composition, structure, formed emulsion morphology, and surface morphology were characterized by Fourier-transform infrared (FT-IR) spectroscopy, conductometer, optical microscope with high speed CCD camera, Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It indicated that hydrophobilization provided TS-1 a moderate wettability, allowing the formation of a stable Pickering emulsion, thus promoting the performance in catalyzing the cyclohexanone/H2O2/NH3·H2O reaction in the absence of organic solvents. What is more, due to alkyl groups grafted to TS-1, the zeolites were comparatively exclusive to the aqueous phase and they are more capable of enduring severe environment, i.e., 200 °C, under autogenic pressure.