Photoelectrocatalysis is an attractive alternative to conventional electrochemical procedures mainly because this procedure allows decreasing the applied potential due to energy assistance from sunlight. The vast majority of the applications in photolectrocatalysis have mainly focused on the study of the oxidation of H₂O and the reduction of CO₂,[1-3] leaving aside its exploitation for the synthesis of more complex organic molecules with high added value. Considering the high potentials, both reducing and oxidizing, that can be obtained from photoelectrochemical processes, these are suitable candidates for designing synthetic routes that allow the preparation of organic products that involve redox transformations in the starting reagents. In this scenario, there are very few examples described in the literature to date where photoelectrodes are used to obtain added value organic species. Recently, it has been described the use of BiVO₄ and WO₃ photoelectrodes for the oxidation of 5-hydroxymethylfurfural, [4] benzyl alcohols,[5-6] furan, [7] tetralines[5], cyclohexane,[8] and glycerol;[9] and Fe₂O₃ photoanodes for the photoelectrocatalytic amination of arenes.[10] In all these cases, the desired product is generated in one of the (photo)electrodes, whereas in the other one the oxidation (or reduction) of a sacrificial agent takes place.

We propose to make a step further in this field, so that both processes, oxidation and reduction, in the photoelectrocatalytic route lead to the synthesis of chemicals of added value without the need of using agents of sacrifice or charge donors. Thus, all the chemicals used are involved in the formation of the final product. In this work we present a route to produce imines, a product of interest as building block in chemical industry, from the photoelectrocatalytic oxidation of alcohols to aldehydes combined with the reduction of nitroarenes into amines. Yields higher than 60 % have been found for the conversion of alcohol into the corresponding aldehyde, after 13 hours reaction, using BiVO₄ as photoelectrode. The contribution of the different process, i.e. alcohol UV oxidation in the presecen of O₂, photocatalytic and photoelectrocatalytic oxidation, to the overall photoelectrochemical reaction are evaluated. The production of side products of interest as H₂O₂ has also been identified.