Agradecimentos: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brasil (CAPES), finance code 001, CAPES/PNPD, Fundação de Amparo à Pesquisa do Estado de São Paulo, FAPESP (2013/07296-2, 2015/19709-5, 2016/23891-6, 2017/12594-3, and 2017/19548-7) and Conselho Nacional de desenvolvimento Científico e Tecnológico, CNPq (150205/2017-1 and 166281/2017-4). The authors also thank the Generalitat Valenciana for Prometeo II/2014/022, Prometeo/2016/079, ACOMP/2014/270, ACOMP/2015/1202, Ministerio de Economia y Competitividad, project CTQ2015-65207-P, FIS2016-75618-R, and MAT2016-80410-P, and Programa de Cooperación Cientifica con Iberoamerica (Brasil) of Ministerio de Educación (PHBP14-00020), and J.A. acknowledges the Ministerio de Economia y Competitividad, "Salvador Madariaga" program, PRX15/00261, and "Universitat Jaume I" project no. UJI-B2016-25 for financial support. This work used computational resources of the "Centro Nacional de Processamento de Alto Desempenho em São Paulo" (CENAPAD-SP), "Centro de Computação John David Rogers" (CCJDR-UNICAMP), and the CENAPAD-RJ (SDumont). The authors are very grateful to the "Serveis Centrals d’Instrumentació Científica (SCIC)" of the University Jaume I for the use of the femtosecond laser equipment and to the "Laboratory of Structural Characterization (LCE/DEMa/UFSCar)" for the use of microscope facilities. The authors would especially like to express their gratitude to Rorivaldo Camargo for the stimulating discussions and help in TEM operation and Enio Longo for the final version of the figures and design contributions Ver menos

Abstract: In nanotechnology research, significant effort is devoted to fabricating patterns of metallic nanoparticles on the surfaces of different semiconductors to find innovative materials with favorable characteristics, such as antimicrobial and photocatalytic properties, for novel applications. We present experimental and computational progress, involving a combined approach, on the antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) of as-synthesized alpha-Ag2WO4 samples and Ag nanoparticle composites (Ag NPs)/alpha-Ag2WO4. The former included two morphologies: hexagonal rod-like (alpha-Ag2WO4-R) and cuboid-like (alpha-Ag2WO4-C), and the latter included composites formed under electron beam, Ag NPs/alpha-Ag2WO4-RE and Ag NPs/alpha-Ag2WO4-CE, and femtosecond (fs) laser irradiation, Ag NPs/alpha-Ag2WO4-RL and Ag NPs/alpha-Ag2WO4-CL. Direct observations of the arrangement of Ag NPs on the Ag NPs/alpha-Ag2WO4 composites irradiated with an electron beam and laser, through transmission electron microscopy (TEM), high-resolution TEM, energy-dispersive X-ray spectroscopy, and field-emission scanning electron microscopy, allow us to investigate the surface morphology, chemical composition, homogeneity, and crystallinity. Therefore, these experimental factors, and in particular, the facet-dependent response of Ag NPs/alpha-Ag2WO4 composites were discussed and analyzed from the perspective provided by the results obtained by first-principles calculations. On this basis, alpha-Ag2WO4-R material proved to be a better bactericidal agent than alpha-Ag2WO4-C with minimum bactericidal concentration (MBC) values of 128 and 256 µg/mL, respectively. However, the Ag NPs/alpha-Ag2WO4-CL composite is the most efficient bactericidal agent of all tested samples (MBC = 4 µg/mL). This superior performance can be attributed to the cooperative effects of crystal facets and defect engineering. These results on the synthesis and stability of the Ag NPs/alpha-Ag2WO4 composites can be used for the development of highly efficient bactericidal agents for use in environmental remediation and the potential extension of methods to produce materials with catalytic applications Ver menos