Silver nanoparticles (NPs) were rapidly synthesized by treating silver ions with a Capsicum annuum L. extract. The reaction process was simple and convenient to handle, and was monitored using ultraviolet-visible spectroscopy (UV-vis). The effect of Capsicum annuum L. proteins on the formation of silver NPs was investigated using X-ray photoemission spectroscopy (XPS), electrochemical measurements, Fourier-transform infrared spectroscopy (FTIR) and differential spectrum techniques. The morphology and crystalline phase of the NPs were determined from transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) spectra. The results indicated that the proteins, which have amine groups, played a reducing and controlling role during the formation of silver NPs in the solutions, and that the secondary structure of the proteins changed after reaction with silver ions. The crystalline phase of the NPs changed from polycrystalline to single crystalline and increased in size with increasing reaction time. A recognition-reduction-limited nucleation and growth model was suggested to explain the possible formation mechanism of silver NPs in Capsicum annuum L. extract.

Catalysts for oxygen reduction reaction (ORR) are crucial in fuel cells. Developing metal-free catalyst with high activity at low-cost and high-volume production remains a great challenge. Here, we report a novel type of nitrogen-doped nanoporous carbon nanosheets derived from a conveniently available and accessible plant, Typha orientalis. The nanosheets have high surface area (the highest surface area can be 898 m 2 g À1 ), abundant micropores and high content of nitrogen (highest content of 9.1 at.%). The typical product exhibits an unexpected, surprisingly high ORR activity. In alkaline media, it exhibits similar catalytic activity but superior tolerance to methanol as compared to commercial 20% Pt/C. In acidic media as well, it shows excellent catalytic ability, stability and tolerance to methanol. This low-cost, simple and readily scalable approach provides a straightforward route to synthesize excellent electrocatalysts directly from biomass, which may find broad applications in the fields of supercapacitors, sensors, and gas uptake. Broader contextElectrocatalysts for the oxygen reduction reaction (ORR) are crucial in fuel cells and other electrochemical devices. It is highly challenging but extremely desirable to develop inexpensive metal-free catalysts, with high activity and with the capability of high-volume production of high yields for fuel cells. In this work, we have reported a novel type of nitrogen-doped nanoporous carbon nanosheets, which has been derived for the rst time from a conveniently available and accessible plant Typha orientalis. The materials have a high surface area, abundant micropores and a high content of nitrogen. A typical product exhibits an unexpected, surprisingly high ORR activity. In alkaline media, it exhibits similar catalytic activity but superior tolerance to methanol than commercial 20% Pt/C. The high activities can be ascribed to the large surface area with abundant micropores, the high content of pyridine and pyrrolic-like nitrogen atoms within the materials and the 3D interpenetrated network structure produced by numerous carbon nanosheets. The products were prepared using the plant Typha orientalis as carbon source and without using any organic solvent. The synthesis strategy is simple, low-cost, and can be easily scaled up for production.

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Anisotropic gold nanoparticles have been prepared by the photochemical reduction in the room-temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) without any additional capping agent. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy have been used to characterize the as-prepared products. The results show that especial shape gold particles can be controlled by [BMIM][BF4] and reaction conditions such as reaction time and reagent concentration. The [BMIM][BF4] is a reaction medium, template, and capping agent. Under different reaction conditions, various morphologies such as sheet (triangle and hexagon) polyhedron of gold nanoparticles can be obtained. The mechanisms of photochemical reduction reaction and controlled growth of gold nanoparticles have also been discussed.

In this paper, we report a novel matchlike zinc oxide (ZnO)/gold (Au) heterostructure with plasmonic-enhanced photoelectrochemical (PEC) activity for solar hydrogen production. The matchlike heterostructure with Au nanoparticles coated on the tip of ZnO nanorods is in situ grown on a zinc (Zn) substrate by using a facile hydrothermal and photoreduction combined approach. This unique heterostructure exhibits plasmonic-enhanced light absorption, efficient charge separation and transportation properties with tunable Au contents. The photocurrent density of the matchlike ZnO/Au heterostructure reaches 9.11 mA/cm(2) at an applied potential of 1.0 V (vs Ag/AgCl) with an Au/Zn atomic ratio of 0.039, which is much higher than that of the pristine ZnO nanorod array (0.33 mA/cm(2)). Moreover, the solar-to-hydrogen conversion efficiency of this special heterostructure can reach 0.48%, 16 times higher than that of the pristine ZnO nanorod array (0.03%). What is more, the efficiency could be further improved by optimizing the Au content of the heterostructure. The formation mechanism of such a unique heterostructure is proposed to explain the plasmonic-enhanced PEC performance. This study might contribute to the rational design of the visible-light-responsive plasmonic semiconductor/metal heterostructure photoanode to harvest the solar spectrum.