The exchange current densities for the as-deposited samples were generally lower than those for the dealloyed samples. The increase in exchange current density for the samples after dealloying is more pronounced (over an order of magnitude) for the samples with larger initial Cu content. This

increase cannot be explained purely by an increase in effective surface area. The measured capacitances generally increased by a factor of 2 to 3 after dealloying (Figure 5), so the additional increase in reactivity must be due to structural and compositional changes in the thin films. Conclusions Electrodeposition and electrochemical dealloying of NiCu thin films were used to fabricate porous samples. The hydrogen evolution reactivity of electrodeposited NiCu samples LY2835219 in vitro was measured before and after some of the Cu was selectively removed. The dealloyed samples are generally more reactive at lower overpotentials, but less reactive at higher overpotentials. The increase in reactivity for the dealloyed samples, as measured

by the exchange current density, cannot be explained only by an increase in effective surface area. Thus, some of the reactivity increase must be due to the changes in composition and structure of the samples from the dealloying procedure. The decrease in reactivity at higher overpotentials is hypothesized to be the result of trapped hydrogen bubbles decreasing the effective surface area of the samples. Further experiments are ongoing in our laboratory

to investigate the effective surface Selleck Copanlisib area of as-deposited and dealloyed samples as a function of potential. The dealloying procedure used here is a promising method for the fabrication of effective catalysts for HER, particularly for use at low overpotentials. Thiamine-diphosphate kinase Acknowledgements This material is based upon work supported by the National Science Foundation under grants no. RUI-DMR-1104725, REU-PHY/DMR-1004811, ARI-PHY-0963317, and MRI-CHE-0959282. References 1. BIBW2992 Tappan BC, Steiner SA, Luther EP: Nanoporous metal foams . Angew Chem Int Ed 2010,49(27):4544–4565.CrossRef 2. Katagiri A, Nakata M: Preparation of a high surface area nickel electrode by alloying and dealloying in a ZnCl 2 -NaCl melt . J Electrochem Soc 2003,150(9):585–590.CrossRef 3. Fukumizu T, Kotani F, Yoshida A, Katagiri A: Electrochemical formation of porous nickel in zinc chloride-alkali chloride melts . J Electrochem Soc 2006,153(9):629–633.CrossRef 4. Hakamada M, Takahashi M, Furukawa T, Mabuchi M: Coercivity of nanoporous Ni produced by dealloying . Appl Phys Lett 2009,94(15):153105.CrossRef 5. Brunelli K, Frattini R, Magrini M, Dabalà M: Structural characterization and electrocatalytic properties of Au 30 Zr 70 amorphous alloy obtained by rapid quenching . J Appl Electrochem 2003,33(11):995–1000.CrossRef 6. Ding Y, Erlebacher J: Nanoporous metals with controlled multimodal pore size distribution . J Am Chem Soc 2003,125(26):7772–7773.CrossRef 7.