Photocatalytic decomposition of formic acid was carried out using both electrochemical and photocatalytic methods within a single-compartment photoelectrochemical cell equipped with nanocrystalline TiO₂ electrodes. Since P25 showed inactivity, Degussa TiO₂ was prepared on plated glass coated with tin oxide. When a potential of +1 V (vs. SCE) was applied to the TiO₂ electrode, a substantial increase in the rate of formic acid decomposition was observed under anaerobic and ambient conditions compared to the open-circuit electrode. However, when the solution was saturated with O₂, applying a positive bias did not produce a significant increase in decomposition rate.

A second cathodic compartment was added to the cell, enabling the simultaneous photocatalytic oxidation of formic acid and the reduction of copper ions from solution. In this system, formic acid was decomposed at the photoanode, while copper ions were efficiently reduced and deposited on the copper mesh cathode with high efficiency.