Identification of the Active Sites on Metallic MoO2-x Nano-Sea-Urchin for Atmospheric CO2 Photoreduction Under UV, Visible, and Near-Infrared Light Illumination

We report an oxygen vacancy (V-o)-rich metallic MoO2-x nano-sea-urchin with partially occupied band, which exhibits super CO2 (even directly from the air) photoreduction performance under UV, visible and near-infrared (NIR) light illumination. The V-o-rich MoO2-x nano-sea-urchin displays a CH4 evolution rate of 12.2 and 5.8 mu mol g(catalyst)(-1) h(-1) under full spectrum and NIR light illumination in concentrated CO2, which is ca. 7- and 10-fold higher than the V-o-poor MoO2-x, respectively. More interestingly, the as-developed V-o-rich MoO2-x nano-sea-urchin can even reduce CO2 directly from the air with a CO evolution rate of 6.5 mu mol g(catalyst)(-1) h(-1) under NIR light illumination. Experiments together with theoretical calculations demonstrate that the oxygen vacancy in MoO2-x can facilitate CO2 adsorption/activation to generate *COOH as well as the subsequent protonation of *CO towards the formation of CH4 because of the formation of a highly stable Mo-C-O-Mo intermediate.

Automated summary

We report an oxygen vacancy (V-o)-rich metallic MoO2-x nano-sea-urchin with partially occupied band, which exhibits super CO2 photoreduction performance under UV, visible and NIR light. The V-o-rich MoO2-x nano-sea-urchin shows significantly higher CH4 evolution rate compared to the V-o-poor MoO2-x, and can even reduce CO2 directly from the air. Experimental and theoretical results suggest that the oxygen vacancy in MoO2-x facilitates CO2 adsorption/activation and subsequent protonation of *CO towards the formation of CH4 due to the formation of a highly stable Mo-C-O-Mo intermediate.