Hot holes in Pt-Cu alloy clusters can act as catalyst to accelerate the intrinsic aerobic oxidation reactions. It is described that under visible light irradiation the synergistic alcohol catalytic oxidation on Pt-Cu alloy clusters (≈1.1 nm)/TiO2 nanobelts could be significant promoted by interband-excitation-generated long-lifetime hot holes in the clusters.

Au–Cu bimetallic nanoparticles supported on a TiO2-nanobelt (TiO2-NB) have been designed and synthesized by a one-pot photodeposition-galvanic replacement method. TEM observation revealed that small-sized metal nanoparticles (less than 2 nm) were uniformly and finely dispersed on the TiO2 nanobelt. Characterization by XRD coupled with XPS demonstrated that the Au–Cu bimetallic nanoparticles are composed of an Au-rich core/CuOx shell structure. The as-synthesized one-dimensional Au–Cu/TiO2-NB nanostructure can be easily assembled into a paper-like porous monolithic catalyst and applied in heterogeneous catalysis. The formed bimetallic nanopaper catalysts presented synergistically enhanced activity and improved stability for catalyzing the aerobic oxidation of benzyl alcohol compared to their monometallic counterparts. It is likely that the Au–CuOx heterostructure is responsible for the superior catalytic properties of the bimetallic Au–Cu/TiO2-NB catalysts, and the catalytic activity can be significantly affected by the Au/Cu ratio. The uniform and high dispersion of metal nanoparticles on TiO2 nanobelts is also believed to contribute to the stability of Au–Cu/TiO2-NB catalysts, suggesting that the one-dimensional TiO2 nanobelts are a desirable support for the preparation of nanoscale metal catalysts.

Well-dispersed small Au–Ag bimetallic nanoparticles (sub-3 nm) on one dimensional TiO2 nanobelts were synthesized by a facile successive photodeposition-galvanic replacement method. Based on these Au–Ag/TiO2-NB nanostructures, a porous paper-like monolithic catalyst was fabricated and exhibited synergistically enhanced activity and stability for catalyzing aerobic oxidation of benzyl alcohol.

The paper presented an alloying/dealloying process for the fabrication of hierarchically porous alloy films (HPAFs). The fabrication process involved electrodeposition of copper on the substrate, annealing to produce new alloy phases, and selective dissolution of copper from the surface. Scanning electron microscopy (SEM) images suggested that the HPAFs were composed of large-sized ligament-channels structures (several micrometers) coupled with small-sized ligament-pores (tens nanometers) interpenetrating the big architectures. Energy dispersive X-ray analysis spectra (EDS) revealed the nonuniform distribution in chemical composition of the large-sized ligament-channel structures. Moreover, we demonstrated that the resulting materials showed catalytic activity for methanol electro-oxidation in alkali solution. We believe that the resulting HPAFs electrode is prospective in the fields of catalysis, sensors, and so on.Highlights► Hierarchically porous alloy films (HPAFs) were synthesized via alloying/dealloying method. ► Hierarchical pores structured from nanometer to micrometer scales. ► Catalysts for direct electrocatalytic oxidation of methanol.

Nanoporous gold (NPG) catalysts were made by free corrosion and the effect of alkali-treatment on NPG has been investigated for the oxidation of CO. After being immersed in alkaline (NaOH or ammonia) solutions, the catalytic activity could be promoted dramatically while used for the room temperature reaction, and this promotional effect could be adjusted by varying the pH values of the alkaline solutions or immersing time. The roles of the alkaline were to provide OH− anions to form Au–OH− sites, which were the active sites to form hydroxyl carbonyl (Au–OCOH−) with CO and activated the oxygen with hydroxyl carbonyl. A probable reaction mechanism was proposed.

Bi2WO6 samples were fabricated by chemical solution decomposition (CSD) method and nanosheet-like Bi2WO6 samples could be obtained by concentrated nitric acid treatment at 70 °C for 20 min. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV–vis diffuse reflectance spectra. Photocatalytic activities of the samples were evaluated by the degradation of rhodamine B (RhB) under visible light irradiation. The temperature of acid treatment obviously influenced morphology and the visible light photocatalytic activity of the Bi2WO6 samples. The nanosheet-like Bi2WO6 photocatalysts obtained by acid treatment exhibited the highest photocatalytic activity under visible light irradiation.

Au−TiO2 nanocomposites have been widely investigated for their potential applications in solar energy conversion, CO oxidation, and methanol reforming reactions. In this study, commercial TiO2 nanoparticles were assembled on the surface of nanoporous gold (NPG) to fabricate novel TiO2/NPG nanocomposite electrodes. Electrochemical and photoelectrochemical techniques were used to investigate the characteristics of the electrodes. Large photocurrent and nearly reversible voltammetric responses were observed for methanol photoelectrocatalysis under UV radiation, indicating an effective elimination of gold surface passivation due to a pronounced synergistic effect between TiO2 and NPG. A possible mechanism was proposed to elucidate such a synergistic effect, which is based on the reaction of the photogenerated reactive intermediates on the surface of NPG. Kinetic studies showed that the coupling of TiO2 with NPG in our system could lead to about a 30% decrease of apparent activation energy for methanol electrooxidation.

Nanoporous gold (NPG) catalysts, made by dealloying Ag/Au alloys, were found to be novel unsupported Au nanocatalysts that exhibited effective catalytic activity and high selectivity (∼99%) for the aerobic oxidation of d-glucose to d-gluconic acid under mild conditions. Systematic studies have been carried out to discuss this new catalytic system, including the activity dependence as functions of pH value, temperature and NPG ligament size, reaction active sites, and reaction kinetics. The possible contribution from the residual Ag atoms trapped in the NPG ligaments was also discussed, which turned out to be unfavorable for the glucose oxidation. The unexpected observation of the catalytic activity from NPG with a ligament size as large as 60 nm indicated that the low-coordinated surface Au atoms should be the reaction active sites for glucose oxidation.

Well-dispersed small Au–Ag bimetallic nanoparticles (sub-3 nm) on one dimensional TiO2 nanobelts were synthesized by a facile successive photodeposition-galvanic replacement method. Based on these Au–Ag/TiO2-NB nanostructures, a porous paper-like monolithic catalyst was fabricated and exhibited synergistically enhanced activity and stability for catalyzing aerobic oxidation of benzyl alcohol.

Au–Cu bimetallic nanoparticles supported on a TiO2-nanobelt (TiO2-NB) have been designed and synthesized by a one-pot photodeposition-galvanic replacement method. TEM observation revealed that small-sized metal nanoparticles (less than 2 nm) were uniformly and finely dispersed on the TiO2 nanobelt. Characterization by XRD coupled with XPS demonstrated that the Au–Cu bimetallic nanoparticles are composed of an Au-rich core/CuOx shell structure. The as-synthesized one-dimensional Au–Cu/TiO2-NB nanostructure can be easily assembled into a paper-like porous monolithic catalyst and applied in heterogeneous catalysis. The formed bimetallic nanopaper catalysts presented synergistically enhanced activity and improved stability for catalyzing the aerobic oxidation of benzyl alcohol compared to their monometallic counterparts. It is likely that the Au–CuOx heterostructure is responsible for the superior catalytic properties of the bimetallic Au–Cu/TiO2-NB catalysts, and the catalytic activity can be significantly affected by the Au/Cu ratio. The uniform and high dispersion of metal nanoparticles on TiO2 nanobelts is also believed to contribute to the stability of Au–Cu/TiO2-NB catalysts, suggesting that the one-dimensional TiO2 nanobelts are a desirable support for the preparation of nanoscale metal catalysts.