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.