Sum-frequency spectroscopy and ellipsometry have been used to study monolayers of the nonionic surfactants poly(ethylene glycol) monododecyl ethers (C12E m ; m = 2−8) at the air−water interface. SF spectra were acquired for areas of 30−70 Å2 per molecule, as determined from literature adsorption isotherms. These spectra show an increase in conformational disorder with increasing area per molecule and, surprisingly, an apparent decrease in the angle of tilt of the methyl group. There was no systematic variation in the SF spectra as a function of the length of the poly(ethylene glycol) chain at fixed areas of 45 and 62 Å2 per molecule. For m ≥ 4, the ellipsometric data suggested that the density of the hydrocarbon region of the chain was independent of m at fixed coverage but that the density decreased for m = 2 and 3. This study suggests that the value of m does not, per se, affect the structure of a monolayer of C12E m at the air−water interface for m = 4−8.

We have studied the oxidation of magnetite to Fe2O3 in an electrolytic cell in which the anode is magnetite and the cathode is platinum. We report cyclic voltammagram data consistent with the hypothesis that magnetite, without oxygen gas production but with hydrogen gas production at the cathode, is occurring. The reaction occurs at a potential at the anode of about 0.3 V vs SCE in 1 M NaOH electrolyte, consistent with colloid experiments which also estimated the equilibrium potential of the hypothesized reaction. Electrode characterization results using BET, XEDS, and macroscopic volume and mass measurements are reported, as well as the measurements of the amount of hydrogen gas generated per unit current. The quantity of gas generated is also consistent with our hypothesis concerning the electrode chemistry. Some samples exhibit evidence of two oxidation reactions occurring at the anode and a possible interpretation of these is also discussed. These results suggest the use of magnetite as an anode in a cell electrolysing water to produce hydrogen gas and Fe2O3. In such an electrolyser, the electrical energy cost of producing hydrogen gas could be significantly lower than the cost in a standard electrolyser. The measured steady state currents, equivalent to about 400 mA/g of magnetite, are too low to make a practical electrolyser. We briefly discuss several ways in which the currents might be increased to the levels required.