Defect-Rich Carbon-Blocked Delocalized Sulfur Quantum Dots for Efficient Catalytic Acetylene Hydrochlorination

Porous carbon-supported quantum dot (QD) catalysts have attracted widespread attention due to their tunable energy level structure, electron transport capability, and quantum confinement effects. However, significant challenges remain in their controlled synthesis and large-scale production. To achieve this, a novel nanodigging technique (NDT) was developed for the facile synthesis of carbon-based catalysts loaded with sulfur quantum dots (S-QDs), and in situ Raman, in situ DRIFTS, and quasi-in situ X-ray photoelectron spectroscopy (XPS) techniques were performed to systematically investigated the formation mechanism of S-QDs on the carbon matrix during microwave heating. The optimal SC-600 catalysts exhibited appreciable catalytic performance in hydrochlorination of acetylene to vinyl chloride (VCM), demonstrating a high space-time yield (STY) of 23.74 kg_VCM kg_S^–1 h^–1, and durability (over 300 h). Experiment and theoretical calculations revealed that the S-QDs, in conjunction with surrounding carbon atoms, form a Frustrated-Lewis-Pair-like structure that displays significant surface charge polarization, thereby improving the selective adsorption and activation of reactants. Specifically, the p−π interactions and nonclassical hydrogen bonding effectively activate acetylene and HCl, respectively, and following a Langmuir–Hinshelwood mechanism to efficiently produce VCM. This discovery provides valuable insights into the design of carbon material surface charge distribution and spatial transfer, facilitating the targeted and controllable design and synthesis of high-efficiency QD catalysts.