Molecular Activation of MoS2 Photocatalysts Enables Direct Reduction of Atmospheric CO2

Abstract The production of solar fuels directly from atmospheric CO2 remains a long-standing goal, primarily because catalysts perform poorly under highly dilute CO2 (approximately 420 ppm) and in the presence of oxygen. Herein, we report a molecular activation strategy that simultaneously enriches the local CO2 concentration and tunes the electronic structure of active sites by integrating basic organic ligands into cobalt-doped MoS2 (MoS2:Co). Density functional theory (DFT) calculations reveal that ligand basicity governs both CO2 adsorption capacity and metal–ligand interactions, enabling precise control over catalytic activity. This synergy, achieved by integrating a ligand of moderate basicity, i.e., 2-methylimidazole (2-MIm), onto the surface of MoS2:Co, results in an over 1800-fold enhancement in formic acid production with >99% selectivity in pure water and without sacrificial agents. Notably, the system can also operate under ambient air and natural sunlight, producing formic acid continuously for five days without external CO2 supply. In situ spectroscopy and DFT calculations underlie the essential role of 2-MIm in enhancing CO2 reduction kinetics by modulating the electronic structure of Co dopants, facilitating electron transfer, and stabilizing intermediates. By effectively bypassing the need for energy-intensive direct air capture, this work establishes a robust and viable pathway for developing decentralized solar refineries that convert air directly into solar fuels.