Fe3O4 nanoparticles immobilized on porous titania in micron-size range were decorated with small-sized gold nanoparticles and used as a plasmonic catalyst for the reduction of 4-nitrophenol. Monodisperse-porous magnetic titania microspheres were synthesized with bimodal pore-size distribution by the sol-gel templating method. Small-sized gold nanoparticles obtained by the Martin method were attached onto the aminated form of the magnetic titania microspheres. A significant enhancement in the catalytic activity was observed using the gold nanoparticle-decorated magnetic titania microspheres compared to gold nanoparticle-decorated magnetic silica microspheres because of the synergistic effect between small-sized gold nanoparticles and titania. The synergistic effect for gold nanoparticle-attached magnetic titania microspheres could be explained by surface plasmon resonance-induced transfer of hot electrons from gold nanoparticles to the conduction band of titania. Using the proposed catalyst, 4-nitrophenol could be converted to 4-aminophenol in an aqueous solution within 0.5 min. The 4-nitrophenol reduction rates were 2.5–79.3 times higher than those obtained with similar plasmonic catalysts. The selection of micron-size, magnetic, and porous titania microspheres as a support material for the immobilization of small-sized gold nanoparticles provided a recoverable plasmonic catalyst with high reduction ability.
A Wittstock, V Zielasek, J Biener, C M Friend, M Bäumer. Nanoporous gold catalysts for selective gas-phase oxidative coupling of methanol at low temperature. Science, 2010, 327(5963): 319–322 https://doi.org/10.1126/science.1183591
4
A Didier, L Feng, R A Jaime. Nanoparticles as recyclable catalysts: The frontier between homogeneous and heterogeneous catalysis. Angewandte Chemie International Edition, 2005, 44(1): 7852–7872
5
L Maolin, C Guofang. Revisiting catalytic model reaction p-nitrophenol/NaBH4 using metallic nanoparticles coated on polymeric spheres. Nanoscale, 2013, 5(23): 11919–11927 https://doi.org/10.1039/c3nr03521b
6
K Kyoko, I Tamao, H Masatake. Reduction of 4-nitrophenol to 4-aminophenol over Au nanoparticles deposited on PMMA. Journal of Molecular Catalysis A Chemical, 2009, 298(1-2): 7–11 https://doi.org/10.1016/j.molcata.2008.09.009
7
D Wang, A Villa, D Su, L Prati, R Schlögl. Carbon-supported gold nanocatalysts: Shape effect in the selective glycerol oxidation. ChemCatChem, 2013, 5(9): 2717–2723 https://doi.org/10.1002/cctc.201200535
8
C Wang, L Chen, Z Qi. One-pot synthesis of gold nanoparticles embedded in silica for cyclohexane oxidation. Catalysis Science & Technology, 2013, 3(4): 1123–1128 https://doi.org/10.1039/c2cy20692g
9
B G Donoeva, D S Ovoshchnikov, V B Golovko. Establishing Au nanoparticle size effect in the oxidation of cyclohexene using gradually changing Au catalysts. ACS Catalysis, 2013, 3(12): 2986–2991 https://doi.org/10.1021/cs400701j
10
Y Wang, S Van de Vyver, K Sharma, Y Román-Leshkov. Insights into the stability of gold nanoparticles supported on metal oxides for the base-free oxidation of glucose to gluconic acid. Green Chemistry, 2014, 16(2): 719–726 https://doi.org/10.1039/C3GC41362D
11
F Cardenas Lizana, S Gomez Quero, H Idriss, M A Keanne. Gold particle size effects in the gas-phase hydrogenation of m-dinitrobenzene over Au/TiO2. Journal of Catalysis, 2009, 268(2): 223–234 https://doi.org/10.1016/j.jcat.2009.09.020
12
L Q Nguyen, C Salim, H Hinode. Performance of nano-sized Au/TiO2 for selective catalytic reduction of NOx by propene. Applied Catalysis A, General, 2008, 347(1): 94–99 https://doi.org/10.1016/j.apcata.2008.06.002
13
L Q Nguyen, C Salim, H Hinode. Promotive effect of MOx (M= Ce, Mn) mechanically mixed with Au/TiO2 on the catalytic activity for nitrogen monoxide reduction by propene. Topics in Catalysis, 2009, 52(6-7): 779–783 https://doi.org/10.1007/s11244-009-9202-8
14
Y C Chang, D H Chen. Catalytic reduction of 4-nitrophenol by magnetically recoverable Au nanocatalyst. Journal of Hazardous Materials, 2009, 165(1-3): 664–669 https://doi.org/10.1016/j.jhazmat.2008.10.034
15
T C Damato, C S Oliveira, R A Ando, P H C Camargo. A facile approach to TiO2 colloidal spheres decorated with Au nanoparticles displaying well-defined sizes and uniform dispersion. Langmuir, 2013, 29(5): 1642–1649 https://doi.org/10.1021/la3045219
16
H Yazid, R Adnan, M A Farrukh. Gold nanoparticles supported on titania for the reduction of p-nitrophenol. Indian Journal of Chemistry, 2013, 52A(2): 184–191
17
K Hyuntae, K Miran, K H Park. Effective immobilization of gold nanoparticles on core-shell thiol-functionalized GO coated TiO2 and their catalytic application in the reduction of 4-nitrophenol. Applied Catalysis A, General, 2015, 502(1): 239–245
18
C Kip, B Maras, O Evirgen, A Tuncel. A new type of monodisperse porous, hydrophilic microspheres with reactive chloroalkyl functionality: Synthesis and derivatization properties. Colloid & Polymer Science, 2013, 292(1): 219–228 https://doi.org/10.1007/s00396-013-3070-2
19
G Günal, Ç Kip, S E Öğüt, H İlhan, G Kibar, A Tuncel. Comparative DNA isolation behaviours of silica and polymer based sorbents in batch fashion: Monodisperse silica microspheres with bimodal pore size distribution as a new sorbent for DNA isolation. Artificial Cells, Nanomedicine, and Biotechnology, 2018, 46(1): 178–184 https://doi.org/10.1080/21691401.2017.1304404
20
K Ö Hamaloğlu, E Sağ, A Tuncel. Bare, gold and silver nanoparticle decorated, monodisperse-porous titania microbeads for photocatalytic dye degradation in a newly constructed microfluidic, photocatalytic packed-bed reactor. Journal of Photochemistry and Photobiology A Chemistry, 2017, 332(1): 60–65 https://doi.org/10.1016/j.jphotochem.2016.08.015
21
T Camli, M Tuncel, S Senel, A Tuncel. Functional, uniform, and macroporous latex particles: Preparation, electron microscopic characterization, and nonspecific protein adsorption properties. Journal of Applied Polymer Science, 2002, 84(2): 414–429 https://doi.org/10.1002/app.10412
Z Ma, Y Guan, H Liu. Synthesis and characterization of micron-sized monodisperse superparamagnetic polymer particles with amino groups. Journal of Polymer Science Part A, 2005, 43(15): 3433–3439 https://doi.org/10.1002/pola.20803
24
K Ö Hamaloğlu, E Sağ, A Tuncel. Magnetic, monodisperse titania microspheres with bimodal pore size distribution by a new sol-gel templating method and their photocatalytic activity. Journal of Porous Materials, 2018, https://doi.org/10.1007/s10934-018-0619-y
25
K Salimi, D D Usta, O Celikbicak, A Pinar, B Salih, A Tuncel. Ti(IV) carrying polydopamine-coated, monodisperse-porous SiO2 microspheres with stable magnetic properties for highly selective enrichment of phosphopeptides. Colloids and Surfaces. B, Biointerfaces, 2017, 153(1): 280–290 https://doi.org/10.1016/j.colsurfb.2017.02.028
26
J Jiao, Y Wei, Y Zhao, Z Zhao, A Duan, J Liu, Y Pang, J Li, G Jiang, Y Wang. AuPd/3DOM-TiO2 catalysts for photocatalytic reduction of CO2: High efficient separation of photogenerated charge carriers. Applied Catalysis B: Environmental, 2017, 209(1): 228–239 https://doi.org/10.1016/j.apcatb.2017.02.076
27
Y Wei, X Wu, Y Zhao, L Wang, Z Zhao, X Huang, J Liu, J Li. Efficient photocatalysts of TiO2 nanocrystals-supported PtRu alloy nanoparticles for CO2 reduction with H2O: Synergistic effect of Pt-Ru. Applied Catalysis B: Environmental, 2018, 236(1): 445–457 https://doi.org/10.1016/j.apcatb.2018.05.043
28
Y Wei, J Jiao, Z Zhao, J Liu, J Li, G Jiang, Y Wang, A Duan. Fabrication of inverse opal TiO2-supported Au@CdS core-shell nanoparticles for efficient photocatalytic CO2 conversion. Applied Catalysis B: Environmental, 2015, 179(1): 422–432 https://doi.org/10.1016/j.apcatb.2015.05.041
29
Y Zhou, Y Zhu, X Yang, J Huang, W Chen, X Lv, C Lia, C Li. Au decorated Fe3O4@TiO2 magnetic composites with visible light-assisted enhanced catalytic reduction of 4-nitrophenol. RSC Advances, 2015, 5(62): 50454–50461 https://doi.org/10.1039/C5RA08243A
30
J Zheng, Y Wu, Q Zhang, Y Li, C Wang, Y Zhou. Direct liquid phase deposition fabrication of waxberry-like magnetic Fe3O4@TiO2 core-shell microspheres. Materials Chemistry and Physics, 2016, 181(1): 391–396 https://doi.org/10.1016/j.matchemphys.2016.06.074
31
Y Zhao, Y Wei, X Wu, H Zheng, Z Zhao, J Liu, J Lia. Graphene-wrapped Pt/TiO2 photocatalysts with enhanced photogenerated charges separation and reactant adsorption for high selective photoreduction of CO2 to CH4. Applied Catalysis B: Environmental, 2018, 226(1): 360–372 https://doi.org/10.1016/j.apcatb.2017.12.071
32
S Majumder, S Dey, K Bagani, S K Dey, S Banerjee, S Kumar. A comparative study on the structural, optical and magnetic properties of Fe3O4 and Fe3O4@SiO2 core-shell microspheres along with an assessment of their potentiality as electrochemical double layer capacitors. Dalton Transactions (Cambridge, England), 2015, 44(1): 7190–7202 https://doi.org/10.1039/C4DT02551B
33
K Tahir, S Nazir, A Ahmad, B Li, S A A Shah, A U Khan, G M Khan, Q U Khan, Z U H Khan, F U Khan. Biodirected synthesis of palladium nanoparticles using Phoenix dactylifera leaves extract and their size dependent biomedical and catalytic applications. RSC Advances, 2016, 6(89): 85903–85916 https://doi.org/10.1039/C6RA11409A
34
A Dawson, P V Kamat. Semiconductor-metal nanocomposites. Photoinduced fusion and photocatalysis of gold-capped TiO2 (TiO2/gold) nanoparticles. Journal of Physical Chemistry B, 2001, 105(5): 960–966 https://doi.org/10.1021/jp0033263
35
P V Kamat. Photophysical, photochemical and photo-catalytic aspects of metal nanoparticles. Journal of Physical Chemistry B, 2002, 106(32): 7729–7744 https://doi.org/10.1021/jp0209289
36
A Pandikumar, S Murugesan, R Ramaraj. Functionalized silicate sol-gel-supported TiO2-Au core-shell nanomaterials and their photoelectrocatalytic activity. ACS Applied Materials & Interfaces, 2010, 2(7): 1912–1917 https://doi.org/10.1021/am100242p
37
Q Wang, Y Li, B Liu, Q Dong, G Xu, L Zhang, J Zhang. Novel recyclable dual-heterostructured Fe3O4@CeO2/M (M 1/4 Pt, Pd and Pt-Pd) catalysts: Synergetic and redox effects for superior catalytic performance. Journal of Materials Chemistry. A, Materials for Energy and Sustainability, 2015, 3(1): 139–147 https://doi.org/10.1039/C4TA05691D
38
Q Zhang, X Jin, Z Xu, J Zhang, U F Rendón, L Razzari, M Chaker, D Ma. Plasmonic Au-loaded hierarchical hollow porous TiO2 spheres: Synergistic catalysts for nitroaromatic reduction. Journal of Physical Chemistry Letters, 2018, 9(1): 5317–5326 https://doi.org/10.1021/acs.jpclett.8b02393
39
S Linic, P Christopher, D B Ingram. Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy. Nature Materials, 2011, 10(12): 911–921 https://doi.org/10.1038/nmat3151
40
Z F Bian, T Tachikawa, P Zhang, M Fujitsuka, T Majima. Au/TiO2 superstructure-based plasmonic photocatalysts exhibiting efficient charge separation and unprecedented activity. Journal of the American Chemical Society, 2014, 136(1): 458–465 https://doi.org/10.1021/ja410994f
41
M W Knight, H Sobhani, P Nordlander, N J Halas. Photodetection with active optical antennas. Science, 2011, 332(1): 702–704 https://doi.org/10.1126/science.1203056
42
J B Priebe, M Karnahl, H Junge, M Beller, D Hollmann, A Bruckner. Water reduction with visible light: Synergy between optical transitions and electron transfer in Au-TiO2 catalysts visualized by in situ EPR spectroscopy. Angewandte Chemie International Edition, 2013, 52(1): 11420–11424 https://doi.org/10.1002/anie.201306504
43
B Y Zheng, H Q Zhao, A Manjavacas, M McClain, P Nordlander, N J Halas. Distinguishing between plasmon-induced and photoexcited carriers in a device geometry. Nature Communications, 2015, 7797(6): 1–7 https://doi.org/10.1038/ncomms8797
44
B Mu, W Wang, J Zhang, A Wang. Superparamagnetic sandwich structured silver/halloysite nanotubes/Fe3O4 nanocomposites for 4-nitrophenol reduction. RSC Advances, 2014, 4(1): 39439–39445 https://doi.org/10.1039/C4RA05892E
45
S Jana, S K Ghosh, S Nath, S Pande, S Praharaj, S Panigrahi, S Basu, T Endo, T Pal. Synthesis of silver nanoshell-coated cationic polystyrene beads: A solid phase catalyst for the reduction of 4-nitrophenol. Applied Catalysis A, 2006, 313(1): 41–48 https://doi.org/10.1016/j.apcata.2006.07.007
46
P Veerakumar, M Velayudham, K L Lub, S Rajagopal. Polyelectrolyte encapsulated gold nanoparticles as efficient active catalyst for reduction of nitro compounds by kinetic method. Applied Catalysis A, 2012, 439-440(1): 197–205 https://doi.org/10.1016/j.apcata.2012.07.008
47
S Sarkar, A K Guria, N Pradhan. Influence of doping on semiconductor nanocrystals mediated charge transfer and photocatalytic organic reaction. Chemical Communications, 2013, 49(1): 6018–6020 https://doi.org/10.1039/c3cc41599f