Semi-artificial leaf interfacing organic semiconductors and enzymes for solar chemical synthesis
Celine W. S. Yeung, Yongpeng Liu, David M. Vahey, Samuel J. Cobb, Virgil Andrei, Ana Margarida Coito, Rita R. Manuel, Inês A. C. Pereira, Erwin Reisner
Abstract
Photoelectrochemical biohybrids combine the advantages of light-harvesting semiconductors and biocatalysts into a single compact device. However, limited device stability, the use of toxic elements, and non-innocent external components make a sustainable artificial photosynthetic reaction difficult to achieve. Here, we introduce organic photoelectrodes connected to an inverse opal TiO 2 matrix that hosts efficient hydrogenase or formate dehydrogenase, driving direct solar fuel synthesis. By co-immobilizing carbonic anhydrase, the organic bulk heterojunction photobiocathodes generate onset potentials of 1 V vs. RHE and photocurrent densities of up to −8 mA cm −2 in a pH-neutral bicarbonate solution, attaining stable H 2 production or selective CO 2 -to-formate conversion over 10 h. Sufficient aqueous formate was produced (∼2.5 mM) to serve as a hydride source for the asymmetric hydrogenation of acetophenone using a synthetic Noyori-Ikariya catalyst. The semi-artificial organic semiconductor—BiVO 4 tandem leaves achieve a solar-to-fuel efficiency of 0.6% and a Faradaic yield of 87% for formate.