Reduction of CO/sub 2/ to methanol and methane by photo and dark reactions on semiconductor and metal electrodes. Annual report, March 1, 1987-March 1, 1988

SRI is pursuing fundamental research directed at activating Cl species that have a potential role in gas-industry processes. During the previous year, SRI advanced the understanding and performance of aqueous CO/sub 2/ reduction to CH/sub 4/ at inexpensive copper electrodes. The advances included use of an HCl surface pretreatment that doubles the rate of CH/sub 4/ formation; rationalization of the effects of different surface pretreatments; analysis of product distributions as a function of voltage and other parameters; identification of CO/sub 2/ as the electroactive species; interpretation of the reactivity difference between CO and CO/sub 2/ reduction; development of a mechanistic model that explains the catalytic properties of Cu, predicts the voltage for onset of CH/sub 4/ formation, and suggests other catalytic systems for investigation; determination of the crystal orientation dependence of CH/sub 4/ formation; rationalization of the effect of plating rate on Cu activity; and, preliminary investigations of other catalyst systems. The current rate of CH/sub 4/ formation is 2 cu ft/sq ft day. During the following year SRI will investigate: the effect of various Cu surface alterations on CH/sub 4/ formation, and other catalytic systems for producing CH/sub 4/ at lower voltage.