Adenine-functionalized graphene oxide as a charge transfer layer to enhance activity and stability of Cu2O photocathode for CO2 reduction reaction

Cuprous oxide (Cu 2 O) is one of the most promising light-absorbing materials for solar energy conversion, attracting extensive attention in photoelectrochemical carbon dioxide reduction reaction (PEC CO 2 RR). However, the inefficient collection of photogenerated charge carriers limits the application of Cu 2 O photocathodes. Herein, adenine biomolecules were introduced into graphene oxide (denoted as A-GO) as a charge transfer layer for coating Cu 2 O photocathode. The A-GO charge transfer layer can improve photoelectrochemical activity and stability of the Cu 2 O photocathode by facilitating the electrons transfer. Under AM 1.5 G illumination, the photocurrent density of the A-GO/Cu 2 O photocathode is 2.74 mA cm −2 at −1.1 V (vs Ag/AgCl), which is 2.23 and 1.56 times higher than that of bare Cu 2 O and GO/Cu 2 O photocathodes, respectively. The Lewis-basic and pyrimidine N sites in adenine biomolecules can assist the Cu 2 O for PEC CO 2 RR. During PEC CO 2 RR, the A-GO/Cu 2 O photocathode shows a high Faradaic efficiency of 69.25% for menthol production. Coating biomolecules functionalized GO as a charge transfer layer was a crucial strategy for building effective and stable Cu 2 O-based photocathodes for PEC CO 2 RR, as illustrated in this study.