Synthesis of formaldehyde from CO2 catalyzed by the coupled photo-enzyme system

•CO2 was converted into formaldehyde by the coupled photo-enzyme catalysis.•The enzyme reduction of CO2 is predominant compared to the photo-reduction.•EDTA is more efficient than H2O while the decomposition cannot be excluded.•For the sequence enzymatic reaction, the second step is rate-limiting.•The yield of formaldehyde can reach 3.83% with the addition of 1 mM NAD+.