A de novo synthesis of gold nanoparticles embedded, nitrogen doped nanoporous carbon nanoparticles (Au@NC) was synthesized in this work. The chloroauroic acid was encapsulated inside zeolitic imidazolate framework-8 (ZIF-8) nanoparticles during the synthesis and later reduced into gold nanoparticles. The as-synthesized gold nanoparticles embedded ZIF-8 (Au@ZIF-8) was then carbonized into Au@NC to enhance the stability of the nanoporous support. The results showed that Au@NC exhibited a porous structure containing 3wt% of gold. 2-Methylimidazole provided abundant nitrogen (19wt%) on the carbon matrix, resulting in hydrophilic and positive charge surface that is useful for the reduction of 4-nitrophenol. The results of the catalytic reaction indicated that the synthesized Au@NC could act as an effective catalyst with turnover frequency (TOF) of 1185 g -1 s -1 , which is higher than that of conventional naked Au nanoparticles (TOF of 339 g -1 s -1 ) and Au nanoparticles on activated carbon (TOF of 89 g -1 s -1 ). We propose that the enhanced performance of the Au@NC resulted from the homogeneous distribution of Au nanoparticles along with the hydrophilic and positive charge surface of nitrogen-doped carbon surface.Catalysis has been involved at the core of nearly all chemical protocols from scientific research to industrial applications. In general, catalysis could be divided into homogeneous and heterogeneous catalysis. Both of homogenous and heterogeneous catalysts have their own advantages and drawbacks. [1] Some homogeneous catalysts have been tried to converted into hetrogeneous catalysts for easy recycling and other advantages. [2] In recent years, not only organic functional groups but also organometallic compounds and metallic nanoparticles have been decorated on different supports to change homogeneous catalyst into heterogeneous catalyst. [3] Mesoporous silica and zeolite are common supports for metal nanoparticles and organic functional groups since silica displays excellent chemical and thermal stability, extreme accessibility, high surface area, and easy functionalization. [4] As an example of such a recent development, Castro and co-workers functionalized ionic liquids on MCM-41 type mesoporous silica, which exhibited enhanced dodecene conversion efficacy as compared to that of the corresponding pure ionic liquids (i.e., 95% vs. 5%). [5] In addition to silica-based supports, metal oxides such as titania, magnesium oxide, and cerium oxide have also been utilized as effective supports for loading metal nanoparticles. [6] Metal oxides are utilized due to the capability for oxygen vacancies in the oxides to reduce the activation energy of catalytic reactions. [7] Other than silica and metal oxides, catalytic supports of carbon-based materials including activated carbon, mesoporous carbon, and graphite have also been widely used owing to their high stability towards acidic or basic environments. [8] Moreover, another advantage of carbon-based supports is the possible interactions between the catalytically ...

Photoelectrodes for dye-sensitized solar cells were fabricated using commercially available zinc oxide (ZnO) nanoparticles and sensitized with the dye N719. This study systematically investigates the effects of two fabrication factors: the ZnO film thickness and the dye adsorption time. Results show that these two fabrication factors must be optimized simultaneously to obtain efficient ZnO/N719-based cells. Different film thicknesses require different dye adsorption times for optimal cell performance. This is because a prolonged dye adsorption time leads to a significant deterioration in cell performance. This is contrary to what is normally observed for titanium dioxide-based cells. The highest overall power conversion efficiency obtained in this study was 5.61%, which was achieved by 26-μm-thick photoelectrodes sensitized in a dye solution for 2 h. In addition, the best-performing cell demonstrated remarkable at-rest stability despite the use of a liquid electrolyte. Approximately 70% of the initial efficiency remained after more than 1 year of room-temperature storage in the dark. To better understand how dye adsorption time affects electron transport properties, this study also investigated cells based on 26-μm-thick films using electrochemical impedance spectroscopy (EIS). The EIS results show good agreement with the measured device performance parameters.

Conductive ink using copper nanoparticles has attracted much attention in the printed electronics industry because of its low cost and high electrical conductivity. However, the problem of easy oxidation under heat and humidity conditions for copper material limits the wide applications. In this study, antioxidative copper inks were prepared by dispersing the nanoparticles in the solution, and then conductive copper films can be obtained after calcining the copper ink at 250 °C in nitrogen atmosphere for 30 min. A low sheet resistance of 47.6 mΩ/□ for the copper film was measured by using the four-point probe method. Importantly, we experimentally demonstrate that the electrical conductivity of copper films can be improved by increasing the calcination temperature. In addition, these highly conductive copper films can be placed in an atmospheric environment for more than 6 months without the oxidation phenomenon, which was verified by energy-dispersive X-ray spectroscopy (EDS). These observations strongly show that our conductive copper ink features high antioxidant properties and long-term stability and has a great potential for many printed electronics applications, such as flexible display systems, sensors, photovoltaic cells, and radio frequency identification.