Deposition of Ag nanoparticles on g-C 3 N 4 nanosheet by N , N -dimethylformamide: Soft synthesis and enhanced photocata
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lasmonic Ag nanoparticles (AgNPs) with narrow distribution were successfully loaded on graphitic carbon nitride (g-C3 N4 ) sheet by thermal polymerization of melamine precursor and a simple wet-chemical pathway in the presence of polyvinylpyrrolidone (PVP). N,N-dimethylformamide (DMF) was used as an efficient reducing agent as well as a solvent and its presence facilitated homogeneous distribution of AgNPs under mild reaction condition and easy control of its particle growth under different precursor amounts. Ag/g-C3N4 composites of different Ag content were prepared, and the phase, chemical structure, morphologies, electronic and optical properties of Ag/g-C3N4 heterostructures were well characterized, respectively. The photocatalytic activity of Ag/g-C3N4 composites was evaluated by the decolorization of methyl orange (MO), and they exhibited superior photocatalytic activity to bulk g-C3N4 under visiblelight irradiation. Influence of Ag content to photocatalytic activity was also discussed and possible mechanism was explored based on the analysis of photoluminescence spectra (PL) and photodecoloration activity.
I. INTRODUCTION
Over the past years, semiconductor photocatalysis has received intense attention as a potential solution to the worldwide energy shortage and environmental purification.1–5 Among the various semiconductor photocatalytic materials, TiO2 is considered as one of the best photocatalysts because of its high activity, long-term stability, low price, and availability, but it can absorb only the UV portion of the solar spectrum owing to its wide band gap of 3.2 eV.6–10 Therefore, it is an urgent issue to search for efficient sunlight or visible-light-driven photocatalysts with appropriate band gap, strong oxidative/reductive ability, and high stability in water solution system. Recently, polymer-like semiconductor material graphitic C3N4 (g-C3N4), which can be used as a metal-free photocatalyst for its nontoxicity, abundance, and medium band gap (2.7 eV), has attracted much attention in the field of photocatalysis, such as solar energy conversion, hydrogen production, and environment purification.11–17 Nevertheless, there are many drawbacks of the g-C3N4 material in the field of photocatalysis, such as high recombination rate of photogenerated electron–hole
Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2014.223 2170
J. Mater. Res., Vol. 29, No. 18, Sep 28, 2014
http://journals.cambridge.org
Downloaded: 13 Mar 2015
pairs, low specific surface area, and low visible-light utilization efficiency. To solve these problems, many methods have been proposed, especially in the field of improving the photocatalytic activity of g-C3N4 under visible light irradiation. One of the most promising methods is to design metal nanoparticles combining with semiconductor composites to facilitate charge separation, among which metals with plasmonic property are attractive. 18,19 Silver, due to its specific optical, electrical, magnetic, catalytic, ant
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