Applied Catalysis A: General 504 (2015) 238–247 Contents lists available at ScienceDirect Applied Catalysis A: General jou rn al hom epage: www.elsevier.com/locate/apcata Tailoring assemblies of plasmonic silver/gold and zinc–gallium layered double hydroxides for photocatalytic conversion of carbon dioxide using UV–visible light Shogo Kawamura a , Magda C. Puscasu b , Yusuke Yoshida a , Yasuo Izumi a,∗ , Gabriela Carja b,∗∗ a Department of Chemistry, Graduate School of Science, Chiba University, Yayoi 1-33, Inage-ku, Chiba 263-8522, Japan b Department of Chemical Engineering, Faculty of Chemical Engineering and Environmental Protection, Technical University, “Gh. Asachi” of Iasi, Bd. Mangeron No. 71, Iasi 700554, Romania a r t i c l e i n f o Article history: Received 17 September 2014 Received in revised form 19 December 2014 Accepted 22 December 2014 Available online 2 January 2015 Keywords: CO2 photoreduction Layered double hydroxide Silver Gold Surface plasmon resonance a b s t r a c t In the search for novel efficient photocatalysts for the conversion of CO 2 into fuels, plasmonic photocata- lysts based on the self-assemblies of silver or gold nanoparticles with [Zn 3 Ga(OH) 8 ] 2 CO 3 ·mH 2 O layered double hydroxide (Zn 3 Ga|CO 3 LDH) were prepared and tested for the photoreduction of CO 2 by H 2 under irradiation with UV–visible light. Ag and Au nanoparticles were obtained directly on the LDHs via the ion-exchange method or the reconstruction method of the LDHs. The catalysts exhibited intense surface plasmon resonance (SPR) effect at 411 and 555 nm attributable to Ag and Au nanoparticles, respectively. The rate of CO 2 photoreduction on Ag/Zn 3 Ga|CO 3 increased by a factor of 1.69 than that of Zn 3 Ga|CO 3 while the methanol selectivity also increased from 39 to 54 mol%. On Au/Zn 3 Ga|CO 3 , the reduction rate of CO 2 was 1.78 times higher than on Zn 3 Ga|CO 3 LDH whereas the methanol selectivity decreased from 39 to 13 mol%. Electron microscopy and UV–visible and X-ray spectroscopy detected particular interactions of the cationic layers of Zn 3 Ga|CO 3 with Ag and Au nanoparticles. Results show that for Ag/Zn 3 Ga|CO 3 cat- alysts, CO 2 photoreduction by H 2 under visible light was promoted by the SPR effect of Ag nanoparticles while for Au/Zn 3 Ga|CO 3 catalysts Au nanoparticles might act as electron-trapping active sites. © 2014 Elsevier B.V. All rights reserved. 1. Introduction The increasing concentration of CO 2 in the atmosphere, as a result of the combustion of the carbon-based fuels, is predicted to result in unacceptable changes in the Earth’s climate [1,2]. The photoreduction of CO 2 to fuels using light energy can contribute simultaneously to reduction of the major greenhouse gas and the development of sustainable energy. A key technological target to reach efficient photoconversion of CO 2 to fuels (i.e. artificial pho- tosynthesis) is to develop an efficient and robust photocatalyst [3]. An important factor limiting the conversion efficiency of almost every active photocatalyst is the high rate of charge carrier recom- bination. Recently, Ingram and Linic [4] demonstrated that the recombination problem was significantly alleviated by assembling plasmonic nanoparticles and semiconductor supports. Moreover, it ∗ Corresponding author. Tel.: +81 43 290 3696; fax: +81 43 290 2783. ∗∗ Corresponding author. Tel.: +40 232 201231; fax: +40 232 201231. E-mail addresses: yizumi@faculty.chiba-u.jp (Y. Izumi), carja@uaic.ro (G. Carja). has been recently reported that in plasmonic nanoparticles/support co-catalytic systems the photo-responsive features of the metal nanoparticles that manifest the surface plasmon resonance (SPR) effect are able to tune and assist the photocatalytic properties of the support. The particular features of the plasmonic nanostruc- tures at the support interface might reduce the charge carrier recombination rate, and thereby enhance the visible-light-induced photocatalytic activities. Layered double hydroxides (LDHs) or hydrotalcite-like materi- als are layered porous matrices belonging to the class of anionic clay (cationic layers intercalating anions) with many actual and poten- tial applications in catalysis [5]. Recently, García group introduced a novel concept of Ti, Ce, or Cr-doped semiconductors based on Zn- containing LDHs [6]. LDHs can be defined by a versatile elemental composition and the ratio, and have basic properties and a high adsorption capacity for CO 2 [7]. LDH photocatalysts comprising Zn and Ga have been reported, in our previous work, to convert CO 2 into methanol or CO using H 2 [8–10]. The photocatalytic reduction of CO 2 using water and LDHs [11] and the combination of photoox- idation catalyst and LDHs were also reported [12]. However, the http://dx.doi.org/10.1016/j.apcata.2014.12.042 0926-860X/© 2014 Elsevier B.V. All rights reserved.