High-transmittance mesoporous TiO2 photoanode enables unilateral illumination to dual-photoelectrode photoelectrochemical cell with opposite configuration

The performance of a dual-photoelectrode photoelectrochemical cell highly depends on cell configuration. Conventional opposite configuration usually requires bilateral illumination at both the photoelectrodes, while the parallel configuration has a large mass transfer resistance between the two ends of the photoelectrodes. Herein, a dual-photoelectrode photoelectrochemical cell with an opposite configuration is developed, in which a high-transmittance mesoporous TiO 2 photoanode and an air-breathing Cu 2 O-CuO nanowires photocathode are adopted. The mesoporous TiO 2 photoanode can absorb incident UV light for photoanodic reactions, and its high transmittance allows for substantial visible light to pass through the photoanode to illuminate the photocathode for reduction reactions. This design not only enables unilateral illumination to the photoelectrochemical cell with an opposite configuration and spectral splitting of sunlight utilization but also enhances light harvesting. Due to these merits, the dual-photoelectrode photoelectrochemical cell with a mesoporous TiO 2 photoanode exhibits an increase in the short current density by 78.6 % and an increase in the maximum power density by 8.1 % compared to the one with the nanoparticles-packed TiO 2 photoanode.