A sustainable catalytic system for the simultaneous CO 2 reduction and alcohol oxidation driven by light Madasamy Thangamuthu , Emerson C. Kohlrausch, Tara Lemercier, Tom Burwell, Matthew Young, Jesum Alves Fernandes, Andrei N. Khlobystov School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom The conversion of carbon dioxide (CO 2 ) into liquid products is a crucial step toward achieving a net-zero economy. Coupling this process with the selective oxidation of organic molecules, rather than water oxidation, offers a dual benefit: CO 2 valorisation and the synthesis of value-added chemicals. These coupled redox reactions become significantly more sustainable when driven solely by light, without the need for an external bias. This can be achieved using a photoactive anode in a photoelectrochemical (PEC) system, a concept that has previously been demonstrated with enzymatic and precious metal-based photoanodes. The current challenge is to implement this concept using earth-abundant and sustainable materials for both the cathode and the photoanode. In this work, we have developed a highly efficient PEC system composed entirely of carbon-based electrodes and thin film materials derived from abundant elements. This system operates under bias-free conditions, enabling the simultaneous light-driven oxidation of alcohols to aldehydes and the reduction of CO 2 to formate, thereby generating two valuable products in a single step. Our photoanode consists of graphitic carbon nitride (g-C 3 N 4 ) and tungsten oxide (WO 3 ) hybrid material thin film deposited on a carbon paper electrode. Under one sun illumination, it achieves a photocurrent density of 0.34 mA cm -2 at 1.23 V vs RHE. This photoanode exhibits impressive performance in the oxidation of 4-methoxybenzyl alcohol to 4-methoxybenzaldehyde, reaching a faradaic efficiency (FE) of 72% and a production rate of 0.55 μmol h -1 . When paired with a tin (Sn) cathode, the system achieves 100% selective CO 2 reduction to formate with a FE of 97%, all under zero applied bias. These results offer a promising strategy for advancing PEC technology using sustainable materials, paving the way for scalable and bias-free CO 2 conversion that simultaneously yields valuable fine chemicals.
Schematic representation of the Co 3 O 4 /WO 3 /g-C 3 N 4 /CP photoanode and Sn/CP cathode design and the band positions alignment with CO 2 reduction and alcohol oxidation reactions.
P94
© The Author(s), 2025
Made with FlippingBook Learn more on our blog