Cu(In,Ga)Se2 for selective and efficient photoelectrochemical conversion of CO2 into CO.

This work describes a high efficiency and selective CIGS-based photocathode for CO 2 reduction. • We establish a photocathode for CO 2 reduction on the base of Cu(In,Ga)Se 2. • The photoelectrode reaches an photocurrent density of 4.8 mA cm−2 at −0.2 V vs. RHE. • The photocathode selectively converts CO 2 into CO at −0.2 V vs. RHE with a faradaic efficiency of 99.3%. • This is the highest record among photocathodes for CO 2 to CO. The performance of photoelectrochemical (PEC) CO 2 reduction on a photocathode is determined by the light absorption, charge separation and charge transfer efficiency of the photocathode according toη total = η abs * η sep * η tran. Herein, we for the first time establish a photocathode for CO 2 reduction on the base of commercially-available p-type Cu(In,Ga)Se 2 (CIGS). CIGS has a very high optical absorption coefficient up to 105 cm−1 in wide wavelength region. It reaches an ultrahigh photocurrent density of 4.8 mA cm−2 at −0.2 V vs. RHE and 11.5 mA cm−2 at −0.7 V vs. RHE. Importantly, by fixing the bias at −0.2 V vs. RHE, the CIGS/CdS/ZnO/AZO photocathode selectively converts CO 2 into CO with a faradaic efficiency of 99.3%. This is the highest record among the state-of-the-art photocathodes for CO 2 to CO. Our work opens new opportunity for CIGS in solar-induced chemical reactions, and is expected to be concerned by researchers who are interested in catalysis and PECs. [ABSTRACT FROM AUTHOR]