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

Abstract The artificial photosynthesis (APS) of carbon‐based chemicals from CO 2 and water is a promising strategy for solar energy conversion and storage. A new Mn‐doped CdS and CdSeTe quantum dot cosensitized TiO 2 photocathode was fabricated and applied to CO 2 reduction in an APS cell with modified BiVO 4 as the counter electrode. The 3 D 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 90 μ m h −1 cm −2 at −0.9 V versus the saturated calomel electrode under 200 mW cm −2 irradiation. Methanol could also be produced by a two‐electrode system under the same conditions. 13 CO 2 ‐labeling experiments were performed to show that the carbon‐based products are derived from CO 2 . A mechanism for CO 2 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.