Enhanced photocatalytic CO2 reduction in H2O vapor by atomically thin Bi2WO6 nanosheets with hydrophobic and nonpolar surface

The artificial carbon dioxide (CO 2 ) photoreduction into useful chemicals utilizing solar energy demands the stable photocatalysts with high-efficiency charge separation and effective CO 2 adsorption capacity. For all this, for the first time, Bi 2 WO 6 photocatalysts with atomically thin structure along with hydrophobic and nonpolar surface are successfully designed and prepared using CTAB as assistant. The ultrathin feature with short diffusion distance significantly facilitates the charge separation. The hydrophobic surface, modified by nonpolar long carbon chains of CTA + , boosts both the mass-transfer and adsorption of CO 2 , meanwhile suppressing the H 2 O adsorption. Hence, the prepared photocatalyst exhibits a high-efficiency photocatalytic conversion of CO 2 in H 2 O vapor without co-catalyst due to high CO 2 concentration and sufficient photogenerated carriers. The photocatalytic mechanisms including adsorption concentration and activation process of CO 2 are further revealed by the in-situ diffuse reflectance infrared fourier transform spectra (DRIFTS). As a new feature, linearly adsorbed CO at 2035 cm −1 is found on hydrophobic surface of Bi 2 WO 6 , and the absorbance of CO is critical to the next reaction step for CH 4 generation. This innovation provides a facile avenue for the design of photocatalysts with remarkable CO 2 capture ability to achieve the practical application of photocatalytic CO 2 reduction.