Artificial Photosynthesis of Methanol by Mn:CdS and CdSeTe Quantum Dot Cosensitized Titania Photocathode in Imine-Based Ionic Liquid Aqueous Solution

The artificial photosynthesis (APS) of carbon-based chemicals from CO2 and water is a promising strategy for solar energy conversion and storage. A new Mn-doped CdS and CdSeTe quantum dot cosensitized TiO2 photocathode was fabricated and applied to CO2 reduction in an APS cell with modified BiVO4 as the counter electrode. The 3D structure of the photocathode constructed by Mn:CdS and CdSeTe quantum dots showed a high efficiency for light harvesting and electron transfer in this system to yield methanol at a rate of 90mh(-1)cm(-2) at -0.9V versus the saturated calomel electrode under 200mWcm(-2) irradiation. Methanol could also be produced by a two-electrode system under the same conditions. (CO2)-C-13-labeling experiments were performed to show that the carbon-based products are derived from CO2. A mechanism for CO2 reduction in this new APS cell was proposed based on the experimental results. In addition, headspace GC was used to quantify the products by an external standard method.