ORIGINAL PAPER Catalytic deactivation of gold surface as a consequence of Prussian blue electrodeposition and removal Pitchiah Esakki Karthik & Chinnaiah Jeyabharathi & Shanmugam Senthil Kumar & Kanala Lakshmi Narasimha Phani Received: 17 October 2012 / Revised: 26 December 2012 / Accepted: 20 January 2013 / Published online: 26 February 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract It is shown that the gold surface is catalytically deactivated and smoothened upon removal of the Prussian blue (PB)–gold nanocomposite formed on the gold surface. Atomic force microscopy proves surface smoothening after PB removal. The voltammetric responses of Ru(NH 3 ) 6 Cl 3 on the smoothened surface remain unaffected, but the reac- tions that involve multistep and inner-sphere electron trans- fer are affected on the smoothened surface as exemplified by hydroquinone, ferrous oxalate redox reactions, and oxygen reduction. These effects are attributed to catalytic deactiva- tion as a consequence of removal of the active sites. Keywords Surface smoothening . Prussian blue . Asperities . Gold nanoparticles . Electron transfer Introduction Prussian blue (PB) phase formation can take place on gold (Au) from a single ferricyanide solution under low pH con- ditions [1, 2]. However, the growth of this phase was found to cease after a few number of potentiodynamic cycles. It was proved by us that another solid-phase gold nanoparticles (AuNPs) is also formed during PB film formation on the Au electrode surface [3]. Obviously, there is an implicit involve- ment of Au surface in the mechanism of ferricyanide decom- position. This was corroborated by our finding that glassy carbon surface does not favor this process as Au does. We also demonstrated [3] that it is possible to arrive at a nanocomposite of particles of both PB and Au but not Fe(II)–CN–Au(III) bridges as in PB analogues [4]. This process proceeds as more than one event, viz., PB formation preceded by Au nuclei formation and interdependent growth of each component of the nanocomposite. Interestingly, this nanocomposite-modified glassy carbon electrode, when subjected to alkali treatment, affords only AuNPs. We examine in this work if these AuNPs are similar to the asperities studied by Scholz et al. [5] that participate in the electrocatalysis of inner-sphere reactions [6]. In what follows, we present our results on the deactivation of the Au surface and surface smoothening, upon PB electrode- position and its chemical removal from the Au substrate. Experimental procedure Materials and methods The analytical grade chemicals, such as potassium ferricyanide (Rankem), potassium nitrate, hydroquinone (Loba), ruthenium hexamine trichloride (Sigma-Aldrich), potassium tris-oxalate (Alfa Aesar), sodium perchlorate (Sigma-Aldrich), perchloric acid (Sigma-Aldrich), lead perchlorate (Sigma-Aldrich), sodi- um hydroxide, and sulfuric acid (Merck) were used in this work. The solutions were prepared in Millipore water (18.2 MΩ cm), and the temperature was maintained at 25 °C. A conventional three-electrode cell was used for the elec- trochemical measurements. The Au working electrode of diameter 0.16 cm was polished with a 4.0-grade emery sheet and alumina slurry, cleaned well with Millipore water and sonicated. Pt foil served as the counter electrode. The potential was controlled using Ag/AgCl as reference electrode during electrochemical measurements. However, all the potentials were referred to RHE. The cyclic/linear-sweep voltammetric experiments were carried out using BAS 100W workstation. Dedicated to Professor Allen J. Bard on his 80th birthday P. Esakki Karthik : C. Jeyabharathi : S. Senthil Kumar : K. L. N. Phani (*) Nanoscale Electrocatalysis and Sensor Research Group, Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630006, India e-mail: klnp56.kp@gmail.com J Solid State Electrochem (2013) 17:3055–3061 DOI 10.1007/s10008-013-2012-8