Formation of rechargeable films on platinum in sulfuric acid solutions of isopolytungstates

Two types of redox processes, with the formation of (a) dissolved reduced forms of tun-states and (b) solid products, occur on a platinum electrode in metastable long-lived true solutions of isopolytungstates (pH similar to 0.5) in the hydrogen adsorption region. The solid products accumulate on the platinum surface as crystalline films capable of reversible recharging. Basic parameters of the films are determined using cyclic voltammetry, x-ray diffractometry, and scanning tunneling microscopy. Based on a spectrophotometric analysis of solutions, redox conversions, observed in the hydrogen range of potentials, are referred to dissolved hepta- and decatungstates present in the system.