(Photo)electrochemical catalysis, a developing discipline within the physical sciences, encompasses diverse processes across various domains. PEC cells have gained significant recognition as critical tools in energy and environmental application. Initially, PEC cells were employed for generating hydrogen fuel through water splitting, however, their utility extends to pollutant degradation, carbon dioxide reduction, and solar fuel production. Despite their established applications, their potential in organic synthesis is still in its nascent stages. Motivated by the desire for environmentally benign and sustainable synthetic routes, the integration of photochemistry and electrochemistry stands as an innovative paradigm, offering a promising approach to support new strategies of organic chemists. PEC cells are attractive due to their abundance and convenience, utilizing the affordable and environmentally friendly power of sunlight. They leverage a diverse selection of photoelectrode materials and redox mediators while operating effectively under gentle reaction conditions. They benefit from a wide range of photoelectrode materials and redox mediators, along with their capacity to operate under mild reaction conditions. In this study, a photoelectrochemical cell was used for tandem bromination of toluene within a unique two-phase electrolyte system. By incorporating a RuOx co-catalyst, the Ta3N5 photoelectrode demonstrated a remarkable selectivity for Br2 close to 100% without simultaneously generating O2. The kinetic study for charge carriers of photoelectrode reveals that the improved charge transfer at RuOx/Ta3N5 interfaces contributed to excellent photoelectrochemical Br2 evolution activity of RuOx decorated Ta3N5 photoanode. The photoelectrochemically produced Br2 was utilized for bromination of α-sp 3 carbon in toluene, (1-methyl)naphthalene, ethylbenzene, or cyclohexane by RuOx/Ta3N5 photoanode with 100% regioselectivity. The coupling of Ta3N5 photoanode and InP photocathode generated H2 and Br2 under light illumination conditions without external bias. This study provides systematic insights into the design of photoelectrodes for solar-driven tandem bromination systems within the unique environment of a two-phase electrolyte system.
