Strategies for Stabilization of Electrodeposited Metal Particles in Electropolymerized Films for H2O Oxidation and H+ Reduction

• Published in: ACS applied materials & interfaces 2013-08, Vol.5 (15), p.7050-7057
• Main Authors: Torelli, Daniel A, Harrison, Daniel P, Lapides, Alexander M, Meyer, Thomas J
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/am401331k

Metal particles were electrodeposited on a variety of conducting substrates, and their electrocatalytic activity toward H2O oxidation to O2 and H+ reduction to H2 was evaluated. Co, Ni, Cu, Pd, Ag, and Pt were all electrodeposited on fluorine-doped tin oxide (FTO) electrodes. Particularly active were Pd and Pt for H+ reduction and Co and Ag for H2O oxidation. When cycled reductively in 0.1 M HClO4, FTO electrodes derivatized with Pt and Pd reached current densities for hydrogen evolution of 18.3 and 13.2 mA/cm2, respectively, at −0.6 V vs normal hydrogen electrode (NHE). FTO electrodes with electrodeposited Co or Ag were cycled oxidatively in H2O buffered to pH 7 with phosphate buffer. Current densities of 10.5 and 8.70 mA/cm2, respectively, were reached at +1.8 V vs NHE with H2O oxidation onsets at +1.3 and +1.4 V, respectively. The impacts on catalytic stability and performance of electrodeposited metals in/on an electrically conductive polymer support were also investigated. Films of poly-[Fe(vbpy)3](PF6)2 (vbpy is 4-methyl-4′-vinyl-2,2′-bipyridine) were generated on FTO by reductive electropolymerization. Significant improvements to the long-term stability of electrodeposited Ag and Pt particles were observed in the poly-[Fe(vbpy)3](PF6)2 support. Films of poly-[M(vbpy)3](PF6)2 with M = Co(II) or Cu(II) were also prepared and evaluated as electrocatalysts for H2O oxidation. Films containing Co(II) reached current densities of 6.0 mA/cm2 at +1.8 V vs NHE in H2O.