Intermediate hydroxide enforced electrodeposited platinum film for hydrogen evolution reaction

摘要

Competitive catalytic activity of platinum (Pt) makes it as a promising cathode material for hydrogen evolution reaction. But cost of Pt makes it impractical for its use in commercial applications. Unlike literature known methods, our study entails on a methodology of ambient temperature electrodeposition of Pt films, without the use of a complexing agent or pH adjustments or both. Pt films are deposited in an electrochemical bath, which is prepared by adding platinum chloride complex [H_2PtCl_6.x H_2O] in triple-distilled water. Pt films deposited at different potentials are analyzed for their morphological (SEM), struc-tural (XRD), electrochemical study (Cyclic Voltammetry and Linear sweep measurements). The growth and catalytic activity of Pt film show strong dependence on applied deposition potential (-0.25 V to -0.40 V) and reduction kinetics of [PtCl_6]~(2-) or [Pt(OH)Cl_5]~(2-) interme-diate hydroxide ions, that occurs during the process. Binding energy (BE) of Pt(4f_(7/2)) peak in a film increases to 72.4 eV (until -0.30 V), which slightly decreases at a deposition potential of -0.40 V. XRD data show changes along (111) and (200) planes, to which [PtCl_6]~(2-) and [Pt(OH)Cl_5]~(2-) intermediate hydroxide ions are found to be responsible. The average particle size with respect to applied potential, obtained from SEM data is found to be 25-40 nm. The catalytic activity (Peak current density in cyclic voltammetry) versus deposition potential data is correlated with Pt film formation by reduction of intermediate hydroxide ions.