Co-doped MoS2 NPs with matched energy band and low overpotential high efficiently convert CO2 to methanol

•Catalyst is consisted of anomalous spherical nanoparticles with a diameter of 30nm.•Novel catalyst exhibits narrow matching energy band and favourable light response.•The formation of methanol follows zero-order kinetics. Co-doped MoS2 NPs (30nm in diameter) was prepared by hydrothermal method and used for photoelectrocatalytic reduction of CO2. Compared with MoS2, the novel catalyst Co-doped MoS2 NPs obtained the valence band and conduction band locating at 0.89V and −0.52V, which leaded to the high efficient photocatalytic reduction performance. In the aspects of electrocatalysis, resistance reduces by 85KΩ, the conductivity of the target material was enhanced greatly, the reduction overpotential for CO2 decreases from −0.82V to −0.64V, which lead to a large improvement on electrocatalytic activity finally. Thus, the Co-doped MoS2 NPs have both excellent photocatalytic performance and excellent electrocatalytic performance. The main CO2 reduction product is methanol, and the yield of which reaches 35mmolL−1 at 350min. The results have guiding significance for the photoelectric catalyst design, which also have theoretical significance for the photoelectrocatalytic reduction of CO2.