Organic Semiconductor-BiVO4 Tandem Devices for Solar-Driven H2O and CO2 Splitting.

Abstract

Photoelectrochemical (PEC) devices offer a promising platform toward direct solar light harvesting and chemical storage through artificial photosynthesis. However, most prototypes employ wide bandgap semiconductors, moisture-sensitive inorganic light absorbers, or corrosive electrolytes. Here, the design and assembly of PEC devices based on an organic donor-acceptor bulk heterojunction (BHJ) using a carbon-based encapsulant are introduced, which demonstrate long-term H2 evolution and CO2 reduction in benign aqueous media. Accordingly, PCE10:EH-IDTBR photocathodes display long-term H2 production for 300 h in a near-neutral pH solution, whereas photocathodes with a molecular CO2 reduction catalyst attain a CO:H2 selectivity of 5.41±0.53 under 0.1 sun irradiation. Their early onset potential enables the construction of tandem PCE10:EH-IDTBR - BiVO4 artificial leaves, which couple unassisted syngas production with O2 evolution in a reactor completely powered by sunlight, sustaining a 1:1 ratio of CO to H2 over 96 h of operation.