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TG-DTA, TEM, and IR were used to investigate the thermal decomposition behavior of poly(N-vinyl-2-pyrrolidone) (PVP). The TG-DTA results show that the thermal decomposition behavior of PVP on platinum (Pt) is quite different from that of pure PVP. For pure PVP, 95.25% is decomposed when the temperature is increased up to 500°C; while under the same experimental condition, PVP coated on the Pt nanoparticles is only 66.7% decomposed. This is further supported by IR measurement. TEM results exhibited that the partially decomposed PVP still plays a role in stabilizing Pt nanoparticles: after heating treatment at 500°C for half an hour, the platinum nanoparticles did not aggregate heavily.

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In this article, a clean method for the synthesis of PtPd/reduced graphene oxide (RGO) catalysts with different Pt/Pd ratios is reported in which no additional components such as external energy (e.g., high temperature or high pressure), surfactants, or stabilizing agents are required. The obtained catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), induced coupled plasma atomic emission spectroscopy (ICP-AES), and electrochemical measurements. The HRTEM measurements showed that all of the metallic nanoparticles (NPs) exhibited well-defined crystalline structures. The composition of these Pt-Pd/RGO catalysts can be easily controlled by adjusting the molar ratio of the Pt and Pd precursors. Both cyclic voltammetry (CV) and chronoamperometry (CA) results demonstrate that bimetallic PtPd catalysts have superior catalytic activity for the ethanol oxidation reaction compared to the monometallic Pt or Pd catalyst, with the best performance found with the PtPd (1:3)/RGO catalyst. The present study may open a new approach for the synthesis of PtPd alloy catalysts, which is expected to have promising applications in fuel cells.

2000255 (1 of 9) Pd-based nanosheet materials have emerged as efficient catalysts for monobasic and polyhydric alcohol oxidation reactions. However, most reported synthetic methods of Pd-based nanosheets (NSs) are nonuniversal and surfactant-involved, leading to residue-covered surfaces with drastically damaged electrocatalytic properties. Herein, a universal, surfactant-free, simple one-pot route is developed for the precise synthesis of a kind of novel self-standing Pd-M (M = Ag, Pb, Au, Ga, Cu, Pt, etc.) NSs with tremella-like superstructures are assembled using ultrathin two-dimensional (2D) NSs. Benefiting from the universal surfactant-free methods, the obtained Pd-M NSs exhibit clean surfaces and stable three-dimensional (3D) self-standing structures that overcome the difficulty of normal close packing and overlapping 2D NSs. The Pd-M (M = Ag, Pb, and Au) NSs with tremella-like structures all show excellent ethanol oxidation reaction (EOR) and ethylene glycol oxidation reaction (EGOR) properties. In particular, with the optimal superstructure, better electronic effect, and promoted toxicity tolerance, the EOR/EGOR mass activities of Pd 7 Ag NSs, Pd 7 Pb NSs, and Pd 7 Au NSs are 8.2/7.3, 7.2/5.7, and 5.3/4.4 times higher than that of commercial Pd/C catalysts. This advanced 3D construction also endows Pd-M NSs with more favorable stability than Pd/C. This study may be extended to Pd-M (M = other metals) NSs and open up more opportunities for broad catalytic applications.

Titanium dioxide (TiO2) nanoparticles-functionalized N-doped graphene (NGR) composites (NGR/TiO2) were prepared through solvothermal treatment approach using exfoliated NGR and tetrabutyl titanate as the staring materials. The composites were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectra, photoelectrochemical, and electrochemical measurements. Nitrogen doping provides favorable nucleation and anchor sites for TiO2 nanocrystals formation on NGR sheets, helping to form an intimate interfacial contact between NGR and TiO2 nanoparticles. Moreover, NGR has higher electrical conductivity than the reduced graphene oxide (RGO) due to the recovery of the sp(2) graphite network and decrease of defects, resulting in more effective charge transfer and charge separation in the NGR/TiO2 composite. NGR/TiO2 nanocomposite demonstrated a higher photocatalytic activity for hydrogen production as compared to its counterpart, TiO2-functionalized RGO composite (RGO/TiO2). This work provides new insights to design new more efficient graphene-based nanocomposite photocatalysts for solar energy conversion.