Green Approach to Synthesis of Pt and Bimetallic Au@Pt Nanoparticles Using Carica Papaya Leaf Extract and Their Characterization

Document Type: Research Paper


Industrial/Environmental Chemistry Unit, Department of Pure and Applied Chemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria


This study reports a green approach to synthesis of monometallic platinum nanoparticles (Pt NPs) and bimetallic aurium@platinum nanoparticles (Au@Pt) using aqueous leaf extract of Carica papaya as a reducing and stabilizing agent. The nature and morphology of as-synthesized PtNPs and bimetallic Au@Pt NPs were characterized using UV/vis spectroscopy (UV–vis), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray (EDX). HRTEM images reveal that the as-synthesized PtNPs are in the size range of 3.94–5.48 nm with average particle size of 4.50±0.80. The HRTEM image of as-synthesized Au@Pt shows distinguishable objects of almost same spherical shape but having different contrast with size ranging from 4.17 to 13.23 nm and average particle size of 8.70±2.50 nm. The EDX data of Au@Pt nanoparticles reflects bimetallic nature, and the individual metal of the bimetallic Au@Pt nanoparicles are present almost in the ratio 2:1. The narrow size distribution and small average size (< 10 nm) of the as-synthesized nanoparticles are highly potential in catalytic applications.


1. Xu, S.B., Yang, Q. Well-dispersed water-soluble Pd nanocrystals: Facile reducing synthesis and application in catalyzing organic reactions in aqueous media. J. Phys. Chem., 2008; C112: 13419-13425
2. Wen, Z.H., Liu, J., Li, J.H. Core/shell Pt/C nanoparticles embedded in mesoporous carbon as a methanol-tolerant cathode catalyst in direct methanol fuel cells. Adv. Mater., 2008; 20: 743-747.
3. Kang, X.H., Mai, Z.B., Zou, X.Y., Cai, P.X., Mo, J.Y. Glucose biosensors based on platinum nanoparticles-deposited carbon nanotubes in sol-gel chitosan/silica hybrid. Talanta
2008; 74: 879-895.
4. Jena, B.K., Raj, C.R. Gold nanoelectrode ensembles for the simultaneous electrochemical detection of ultratrace arsenic, mercury, and copper. J. Phys. Chem., 2008; C112: 3496-3502.
5. Kuo, T.J., Huang, M.H.J. Gold-catalyzed low-temperature growth of cadmium oxide nanowires by vapor transport. J. Phys. Chem., 2006; B110: 13717–13721.
6. Abdelrahman, A. I., Mohammad, A. M., Okajima, T., Ohsaka, T. Fabrication and Electrochemical Application of Three-Dimensional Gold Nanoparticles: Self-Assembly. J.
Phys. Chem., 2006; B110: 2798–2803.
7. Huang, T., Meng, F., Qi, L. Controlled synthesis of dendritic gold nanostructures assisted by supramolecular complexes of surfactant with cyclodextrin. Langmuir, 2010; 26: 7582–7589.
8. Liu, Y., Liu, L., Guo, R. Br-induced facile fabrication of sponge-like gold/amino acid nanocomposites and their applications in surface-enhanced raman scattering. Langmuir, 2010;
26: 13479–13485.
9. Wanjala, B.N., Luo, J., Fang, B., Mott, D., Zhong, C. J. Gold-platinum nanoparticles: alloying and phase Segregation. J. Mater. Chem., 2011; 21: 4012–4020.
10. Vyas, S. J., Khatri, T.T., Ram, V.R., Dave, P.N. Biochemical constituents in leaf of Carica papaya - Ethnomedicinal plant of Kachchh region. Int. Lett. Nat. Sci., 2014; 12: 16-20.
11. Gogna, N., Hamid, N., Dorai, K. Metabolomic profiling of the phytomedicinal constituents of Carica papaya L. leaves and seeds by 1H NMR spectroscopy and multivariate statistical analysis. J. Pharm. Biomed. Anal. 2015; 115: 74–85
12. Nasrollahzadeh, M., Enayati, M., Khalaj, M. Synthesis of N-arylureas in water and their N- arylation with halides using copper nanoparticles loaded on natural Natrolite zeolite under ligand-free conditions. RSC Adv. 2014; 4: 26264–26270.
13. Nasrollahzadeh, M., Sajadi, S.M., Rostami-Vartooni, A., Khalaj, M. Green synthesis of palladium nanoparticles using Hippophae rhamnoides Linn leaf extract and their catalytic activity for the Suzuki-Miyaura coupling in water. J. Mol. Catal. A. Chem., 2015; 396: 31- 39
14. Stepanov, A.L., Golubev, A.N., Nikitin, S.I., Osin, Y.N. A Review on the fabrication and properties of platinum nanoparticles. Rev. Adv. Mater. Sci., 2014; 38:160–175
15. Ghosh, S. K., Pal, T. Interparticle coupling effect on the surface plasmon resonance of gold nanoparticles: from theory to applications. Chem. Rev., 2007; 107: 4797–4862.
16. Radziuk, D.V., Zhang, W., Shchukin, D., Mohwald, H. Ultrasonic formation of gold- silver alloy nanoparticles. Small, 2010; 6: 545–553
17. Compagnini, G., Messina, E., Puglisi, O., Cataliotti, R.S., Nicolosi, V. Spectroscopic evidence of a core-shell structure in the earlier formation stages of Au-Ag nanoparticles by pulsed laser ablation in water. Chem. Phys. Lett., 2008; 457: 386–390.
18. Kreibig, U., Genzel, U. Optical absorption of small metallic particles. Surf. Sci. 1985; 156: 678–700.
19. Devaty, R. P., Sievers, A. Mie resonance for spherical metal particles in an anisotropic dielectric. J. Phys. Rev., 1985; B32: 1951–1954.
20. Pritchard, J., Kesavan, L., Piccinini, M., He, Q. et al. Direct synthesis of hydrogen peroxide and benzyl alcohol oxidation using Au-Pd catalysts prepared by sol immobilization, Langmuir, 2010; 26: 16568 – 16577.