The possibility to harness the intrinsic properties of bicontinuous microemulsions (BCME) has led to their application as nanocages in the synthesis of nanocoral-shaped Pt hierarchical superstructures (PtHSs). We employed two different platinum precursors (oil-soluble and water-soluble) and sodium borohydride (NaBH4) was used as reducing agent. PtHSs were observed to be pure and nanocrystalline, with small crystallite size (4.5–6.5 nm). XPS showed that the nanostructures are composed of Pt (0). The electrochemical surface areas obtained were 8.7 m2/g, 35.1 m2/g and 20.9 m2/g for PtH–O (synthesized using oil-soluble precursor), PtH-A2 and PtH-A4 (synthesized using 2 and 4% water-soluble Pt precursor), respectively. Linear sweep voltammetry (LSV), Tafel plots and electrochemical impedance spectroscopy (EIS) were used to study the hydrogen evolution reaction process. PtH-A2 showed an overpotential of 68 mV at 10 mA cm−2, a Tafel slope of 30 mV dec−1 and a low charge transfer resistance of 3.39 Ω. The stability of the PtHSs was tested before and after 1000 LSV cycles with minimal loss of current density. The improved electrochemical properties recorded, are due to the unique Pt hierarchical superstructure, which is key for the electrocatalytic performance. Through this research, the “template effect” of bicontinuous microemulsions towards the synthesis of metallic hierarchical superstructures is demonstrated for the first time.
|Original language||English (US)|
|State||Published - Jun 13 2020|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We are grateful to CONACYT for financial support (Fronteras de la Ciencia Project: FC 2016/1700). E. T. Adesuji acknowledges financial support from CONACYT (Ph.D. Grant). M. Videa thanks the School of Engineering and Sciences at Tecnologico de Monterrey for partial funding provided through the Research Chair of Photonics and Quantum Systems. Authors acknowledge Francisco E. Longoria, J. Alejandro Arizpe, Nayeli Pineda and L. Gerardo Silva (CIMAV Monterrey) for their help with XRD, HRTEM-STEM, SEM and XPS measurements; and Victor A. Luna Flores and Miguel A. Esneider Alcala for their help in cutting the electrodes. We also acknowledge NaNoTeCh, the National Nanotechnology Laboratory of Mexico, for HRTEM/STEM measurements. We acknowledge Karla I. Gallardo-Sanchez for her help drawing the 3D nanosponge-like structure of a bicontinuous microemulsion featuring in the left hand side of the TOC figure.