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Kochuveedu, Saji Thomas,Kim, Dong-Pyo,Kim, Dong Ha American Chemical Society 2012 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.116 No.3
<P>This work is focused on the development of a surface plasmon-induced visible light active photocatalyst system composed of silica–titania core–shell (SiO<SUB>2</SUB>@TiO<SUB>2</SUB>) nanostructures decorated with Au nanoparticles (Au NPs). The influence of size and distribution of Au NPs on photocatalysis, its fabrication methods, and exploration of the mechanism of visible light activity were investigated. A favorable architecture of SiO<SUB>2</SUB> beads with a thin layer of TiO<SUB>2</SUB> was decorated with Au NP arrays having different size and areal density. Surface modification of SiO<SUB>2</SUB>@TiO<SUB>2</SUB> leads to a viable and homogeneous loading of Au NPs on the surface of TiO<SUB>2</SUB>, which renders visible light-induced photocatalytic activity on the whole TiO<SUB>2</SUB> surface. An optimized system employing Au NP arrays with 15 nm size and 700/μm<SUP>2</SUP> density showed best catalytic efficiency due to a synergistic effect of the firm contact between Au NPs and TiO<SUB>2</SUB> and efficiently coupled SPR excitation. A brief mechanism relating the electron transfer from surface-plasmon-stimulated Au NPs to the conduction band of TiO<SUB>2</SUB> is proposed.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-3/jp209520m/production/images/medium/jp-2011-09520m_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp209520m'>ACS Electronic Supporting Info</A></P>
Kochuveedu, Saji Thomas,Kim, Dong Ha RSC Pub 2014 Nanoscale Vol.6 No.10
<P>The interaction between light and matter is the fundamental aspect of many optoelectronic applications. The efficiency of such devices is mainly dictated by the light emitting properties of fluorophores. Unfortunately, the intensity of emission is adversely affected by surface defects, scattering and chemical instability. Therefore, enhancing the luminescence of fluorophores is necessary for better implementation of nanocomposites in biological and optical applications. There are many interesting phenomena which can be observed if the characteristics of the fluorophores and metal nanoparticles are integrated. Photoluminescence (PL) by fluorophores can be enhanced or quenched by the presence of neighboring plasmonic metal nanostructures. An unambiguous study of the mechanism behind the enhancement and the quenching of emission is necessary to obtain new insight into the interactions between light and metal-fluorophore nanocomposites. In this review the core aspect of combining plasmonic metal nanostructures with fluorophores is discussed by considering various functional roles of plasmonic metals in modifying the PL properties reported by various research groups. A few representative applications of SPR mediated luminescence are also discussed.</P>
Kochuveedu, Saji Thomas,Jang, Yoon Hee,Kim, Dong Ha The Royal Society of Chemistry 2013 Chemical Society reviews Vol.42 No.21
<P>Metal oxide semiconductors hold great promise for applications in energy conversion and storage, environmental remediation, optoelectronics, memory, light emission and other areas, but critical factors such as the high rate of charge-carrier recombination and limited light absorption have restricted more practical and viable applications. The remarkable ability of plasmonic noble metals to concentrate and scatter visible light has found a versatile potential in harvesting and converting solar energy. Plasmonic nanostructures of noble metals in combination with semiconductors offer a promising future for the next generation of energy needs. The overlap of the spectral range of the incident photon with absorbance wavelength of the semiconductor and the surface plasmon bands of the plasmonic metal provides a useful tool to predict the enhancement in optical and electrical properties of hybrid semiconductor-noble metal nanostructures. Here we make an attempt to comprehensively review the role of plasmonic noble metals in the enhanced functions for photocatalytic activity, photoenergy conversion in DSSCs, enhanced light emission and photochromatism. We mainly focus on the improvement of performance in TiO<SUB>2</SUB> or ZnO in combination with noble metals on representative photophysical applications. The mechanism behind their interaction with light is discussed in detail in each section.</P> <P>Graphic Abstract</P><P>An overview of the interaction mechanism between light and noble metal–metal oxide semiconductor nanostructures and their state-of-the-art photophysical applications. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cs60043b'> </P>
Boppella, Ramireddy,Kochuveedu, Saji Thomas,Kim, Heejun,Jeong, Myung Jin,Marques Mota, Filipe,Park, Jong Hyeok,Kim, Dong Ha American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.8
<P>In this contribution we have developed TiO2 inverse opal based photoelectrodes for photoelectrochemical (PEC) water splitting devices, in which Au nanoparticles (NPs) and reduced graphene oxide (rGO) have been strategically incorporated (TiO2@rGO@Au). The periodic hybrid nanostructure showed a photocurrent density of 1.29 mA cm(-2) at 1.23 V vs RHE, uncovering a 2-fold enhancement compared to a pristine TiO2 reference. The Au NPs were confirmed to extensively broaden the absorption spectrum of TiO2 into the visible range and to reduce the onset potential of these photoelectrodes. Most importantly, TiO2@rGO@Au hybrid exhibited a 14-fold enhanced PEC efficiency under visible light and a 2.5-fold enrichment in the applied bias photon-to-current efficiency at much lower bias potential compared with pristine TiO2. Incident photon-to electron conversion efficiency measurements highlighted a synergetic effect between Au plasmon sensitization and rGO-mediated facile charge separation/transportation, which is believed to significantly enhance the PEC activity of these nanostructures under simulated and visible light irradiation. Under the selected operating conditions the incorporation of Au NPs and rGO into TiO2 resulted in a remarkable boost in the H-2 evolution rate (17.8 mu mol/cm(2)) compared to a pristine TiO2 photoelectrode reference (7.6 mu mol/cm(2)). In line with these results and by showing excellent stability as a photoelectrode, these materials are herin underlined to be of promising interest in the PEC water splitting reaction.</P>