A heterostructured CoAl-layered double hydroxide/MoS2 nanocomposite photocatalyst (CoAl-LDH/MoS2) for CO2 photoreduction was prepared by simple electrostatic interactions. The syngas ratio (H2 : CO) was precisely tuned from 1.3 : 1 to 15 : 1 by altering only the catalyst concentration in the photocatalytic CO2 reduction system under visible light (λ > 400 nm). Interestingly, a rather high evolution rate can be obtained from CO2 photoreduction to CO up to 4575 μmol g-1 h-1 even under irradiation above 500 nm.