Defects Induced in Situ Reconstruction of CdS with Oxygen-Tolerance Up to 23% in the Photocatalytic CO2 Reduction.

Abstract

Direct driving the photocatalytic reduction of CO2 from air or flue gas to produce value-added chemicals and fuels is very challenging due to the suppressing effect of the more favorable thermodynamically oxygen reduction reaction (ORR). Herein, we presented a novel oxygen-involved reconstruction pathway on a unique defective CdS-D in the photocatalytic reduction of CO2. The material is highly tolerant to O2 and generates 2766.7 µmol g-1 h-1 of CO under visible light irradiation in the presence of up to 23% content of O2. Intriguingly, instead of inhibiting the performance of CO2 reduction, the presence of oxygen positively promotes it, CO generation rate is up to 5124 µmol g-1 h-1 after multiple experimental cycles. The meticulously structural analysis reveals that the CdS-D with abundant defects tended to accumulate photogenerated holes, and S2- is oxidized to SO4 2- in the presence of oxygen to produce Cd2SO4(OH)2 as the active center for preferable CO2 adsorption and inhibit the O2 adsorption, which is the root cause for the high tolerance of oxygen in CO2 reduction (CO2RR). This work reveals a unique reconstruction process of sulfides photo corrosion, which provides a new idea for realizing the direct conversion of low-concentration CO2 by omitting expensive carbon capture or purification in industrial carbon resource utilization.