Two-Dimensional CuTCNQ Built From Supercritical CO2-Induced Conformational Transform for Charge Transfer and Electron Modulation.

The two-dimensional (2D) metal-organic frameworks (MOFs) features intrinsic structural peculiarities and high structural design ability, which is considered as a unique platform for prominent electrical and optical applications. A deeper understanding of the electrical and optical properties that are determined by the function of 2D MOFs is crucial for advancing optoelectronic applications. Herein, we propose a novel strategy to enhance light utilization, charge transfer ability and electron dynamics of 2D MOFs by modulating the coordinative environment. The bulk copper tetracyanoquinodimethane (CuTCNQ) is converted into 2D nanosheets (2D CuTCNQ) via the assistance of supercritical carbon dioxide (SC CO2). The solvent effects of SC CO2 significantly tune the thermodynamical kinetic of bulk CuTCNQ, leading to partial detachment of ligands and the formation of 2D CuTCNQ with unique electron configuration. Simultaneously, 2D CuTCNQ exhibits broadened visible light absorption and accelerated electronic kinetics in comparison with bulk CuTCNQ. Further, the optimized 2D CuTCNQ was employed as a photoanode and it exhibits significantly enhanced photoelectrochemical (PEC) performance, highlighting the potential application in optoelectronic technology. Therefore, such coordinative environment modulation strategy via SC CO2 opens new avenues to optimize photoelectric properties, and as well as to provide rational design on multifunctional 2D MOFs.