Organic Semiconductor-BiVO<sub>4</sub> Tandem Devices for Solar-Driven H<sub>2</sub>O and CO<sub>2</sub> Splitting.

Yeung, Celine Wing See; Andrei, Virgil; Lee, Tack Ho; Durrant, James Robert; Reisner, Erwin · Adv Mater · 2024

basic_science · Level V

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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 H<sub>2</sub> evolution and CO<sub>2</sub> reduction in benign aqueous media. Accordingly, PCE10:EH-IDTBR photocathodes display long-term H<sub>2</sub> production for 300 h in a near-neutral pH solution, whereas photocathodes with a molecular CO<sub>2</sub> reduction catalyst attain a CO:H<sub>2</sub> selectivity of 5.41±0.53 under 0.1 sun irradiation. Their early onset potential enables the construction of tandem PCE10:EH-IDTBR - BiVO<sub>4</sub> artificial leaves, which couple unassisted syngas production with O<sub>2</sub> evolution in a reactor completely powered by sunlight, sustaining a 1:1 ratio of CO to H<sub>2</sub> over 96 h of operation.