Multisite-steered C–C coupling for photocatalytic air-concentration CO2 reduction into C2H6
Photocatalytic conversion of atmospheric CO2 (0.03%) into multi-carbon fuels remains a grand challenge due to the high energy barrier of C–C coupling and the low concentration of CO2. Here, we report the construction of multiple metal pair sites on metal oxide nanosheets to steer C–C coupling, enabling efficient photoreduction of air-concentration CO2 to ethane (C2H6). As a prototype, Au nanoparticles were anchored on Bi4Ti3O12 nanosheets (Au-Bi4Ti3O12). High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the formation of Au-Ti metal pair sites at the interface. In situ Fourier transform infrared spectroscopy revealed the presence of *OCCOH intermediate on Au-Bi4Ti3O12 during CO2 photoreduction, which was absent on pristine Bi4Ti3O12. Density functional theory calculations showed that the Gibbs free energy for *CO–COH formation on Au-Bi4Ti3O12 is 2.23 eV, significantly lower than that on Bi4Ti3O12 (3.59 eV), indicating facilitated C–C coupling. Consequently, Au-Bi4Ti3O12 exhibited a C2H6 evolution rate of 2.58 μmol g−1 h−1 under 0.03% CO2, whereas Bi4Ti3O12 produced only C1 products (CO and CH4). This work demonstrates the first single-catalyst photoreduction of atmospheric CO2 to C2H6, highlighting the effectiveness of engineered multiple active sites in overcoming the C–C coupling bottleneck.