Visible-light driven conversion of CO2 over Cu2O/MXene composites

VISIBLE LIGHT-DRIVEN CONVERSION OF CO2 OVER Cu2O/MXene COMPOSITES Magdaléna Linková, Pavla Eliášová, Luis A. M. Carrascosa, Jiří Čejka Faculty of Science, Charles University, Albertov 6, 128 00 Praha 2 This research focuses on converting carbon dioxide, a prominent greenhouse gas, into value-added products through photo-electrocatalytic processes. We investigate Cu2O as our primary photoresponsive material due to its ability to be activated by visible light and its suitable redox potential for CO2 conversion. Our approach seeks to address key challenges with Cu2O, such as photocorrosion and rapid charge recombination. To this end, we examined p,n-heterojunction semiconductors composed of Cu2O and TiO2, incorporating non-precious-metal-based co-catalysts, specifically MXenes (Scheme 1).¹ Treating MXenes, particularly Ti3C2Tx, at temperatures above 350°C and under varying atmospheres led to the in-situ formation of TiO2 directly on the MXene surface. We prepared a series of electrodes using fluorine-doped tin oxide (FTO) glass as a substrate, with a layer of electrodeposited Cu2O and MXene or TiO2-MXene spray-coated on top. On the prepared photo-electrocatalysts, we conducted linear sweep voltammetry tests using a 150W Xe-lamp in a 0.5M K2SO4, 0.5M KHCO3 electrolyte, saturated with argon or CO2. Additionally, product analysis was performed under photo-electrocatalytic conditions after 2 hours of irradiation using gas chromatography with TCD and BID detectors. CO2 conversion on the bare Cu2O electrode produced ethanol. When Cu2O was coated with pre-calcined Ti3C2Tx, product selectivity shifted toward CO, H2, and CH3COOH. In this contribution, we will explore the relationship between the in-situ formed TiO2 on Ti3C2Tx at various temperatures and atmospheres, and the overall catalytic performance of the photocathodes. Acknowledgement: Authors acknowledge Prof. Michele Aresta and Dr. Tomasz Baran for CO2RR product analysis performed at IC2R Ltd - P.IVA 07459780727 - via Camillo Rosalha 49, 70124, Bari, Italy. This work was financed by the EU within Horizon Europe Research – DESIRED project (project code: 101083355). References: 1 Low, J. et al. TiO2/MXene Ti3C2 Composite with Excellent Photocatalytic CO2 Reduction Activity. Journal of Catalysis 2018, 361, s55–266. DOI: 10.1016/j.jcat.2018.03.009 Scheme 1: Energy band structure of Cu2O, TiO2 and MXene, and redox potential of various CO2 products formation. Figure 1: Linear sweep voltammetry of FTO/Cu2O/TiO2-MXenes in 0.5M K2SO4, 0.5M KHCO3 saturated CO2 under chop light irradiation.