In-situ formation of the heterovalent 2D Ti3C2Tx@MOF-CuII/CuI for their continuous and high efficiency photothermal and photocatalytic reduction of CO2

In-situ construction of a Ti 3 C 2 T x @MOF heterojunction with the heterovalent Cu 2+ /Cu + sites. • Exceptional CO production rate of 141.6 μmol·g −1 ·h −1 via synergistic photothermal and pseudo-greenhouse effects. • The proper ratio of Cu 2+ /Cu + endows the 2D Ti 3 C 2 T x @MOF-CuII/CuI heterojunctions with good cyclic catalysis. • DFT reveals Cu + sites facilitate CO 2 adsorption and reduce energy barrier in the rate-determining step during CO 2 reduction. The direct photocatalytic reduction of CO 2 into valuable chemicals and fuels using non-precious metal catalysts offers a promising strategy to address the energy crisis and mitigate carbon emissions. However, designing highly efficient photocatalysts remains a significant challenge. In this work, we fabricate two-dimensional (2D) Ti 3 C 2 T x @MOF-CuII/CuI heterojunctions that exhibit a CO evolution rate of 141.6 μmol·g −1 ·h −1 , which is approximately 21.8 and 13.0 times that of pristine 2D Ti 3 C 2 T x and 2D MOF Cu, respectively. Furthermore, the synergistic combination of the photothermal effect of Ti 3 C 2 T x and the nanoscale pseudo-greenhouse effect of the MOF-Cu layers further enhances the photocatalytic activity of the heterojunction, surpassing that of previously reported MXene-based materials. Characterization and computational studies reveal that the high intrinsic reducibility of Ti 3 C 2 T x drives the reduction of about 53% of Cu 2+ to Cu + in the resulting 2D Ti 3 C 2 T x @MOF-CuII/CuI heterojunctions. The abundant Cu 2+ /Cu + sites are uniformly distributed throughout the heterostructure, leading to a reduced energy barrier for key reaction intermediates. In addition, the proper ratio of Cu 2+ /Cu + endow the 2D Ti 3 C 2 T x @MOF-CuII/CuI heterojunctions with good cyclic catalysis, thus realizing the continuous photocatalytic reduction. This study provides deep insights into the construction of heterovalent Cu 2+ /Cu + heterojunctions based on MOFs and MXene, enabling the highly efficient collaborative photothermal and photocatalytic CO 2 reduction. Schematic illustration of the 2D Ti 3 C 2 T x @MOF-CuII/CuI heterojunction for synergistic photothermal and photocatalytic CO 2 reduction. Download: Download high-res image (104KB) Download: Download full-size image