Figure 2.

Performance for photoreduction of CO₂ into CH₄. Amounts of CH₄ and CO produced as a function of the visible illumination time over (a) NNU-13 and (b) NNU-14; (c) the total product yield and selectivity of gas products in the photoreduction of CO₂; (d) the mass spectra of ¹³CH₄ recorded under a ¹³CO₂ atmosphere, and the detail spectra of the comparative experiments are shown in supplementary information. The photoreduction of the CO₂ reaction occurred in the H₂O/TEOA (14:1 V/V, 30 mL) solution with photocatalyst (5 mg) and illuminated via a Xe arc lamp with a UV-cutoff filter (420–800 nm).