Highly Selective Tandem Photoelectrochemical C-H Activation via Bromine Evolution Reaction in Two-Phase Electrolyte.

The development of environmentally friendly and safe chemical processes using renewable energy sources is important. In this study, a photoelectrochemical (PEC) cell was used for the tandem bromination of sp 3 carbon within a unique two-phase electrolyte system. By incorporation of a RuO x cocatalyst, the Ta 3 N 5 photoelectrode demonstrated a remarkable selectivity for Br 2 close to 100%. The kinetic study for charge carriers of photoelectrodes reveals that the improved charge transfer at Ta 3 N 5 /RuO x interfaces contributed to excellent photoelectrochemical Br 2 evolution activity. The photoelectrochemically produced Br 2 was utilized for bromination of α- sp 3 carbon in toluene, 1-methylnaphthalene, ethylbenzene, or cyclohexane by the Ta 3 N 5 /RuO x photoanode with 100% regioselectivity. The coupling of the Ta 3 N 5 photoanode and InP photocathode generated H 2 and Br 2 under light illumination 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.