The curvature structure unlocks an ultra-efficient metal-free carbon catalyst surpassing gold for acetylene hydrochlorination

Abstract

Metal-free carbon catalysts have garnered significant attention since their inception. Despite substantial advancements, including widely adopted strategies such as heteroatom doping and defect engineering, their catalytic performance remains inferior to that of metal-based catalysts. In this study, we have predicted and demonstrated that the curvature of carbon plays a pivotal role in the adsorption of acetylene and the overall catalytic performance. First-principles calculations suggest that a tip-enhanced local electric field at the defect site on the curved carbon catalyst enhances the reaction kinetics for acetylene hydrochlorination. The experimental results highlight the structural advantages of the curved defect site, revealing that high-curvature defective carbon (HCDC) demonstrates an adsorption capacity for acetylene that is almost two orders of magnitude higher than that of defective carbon. Notably, HCDC achieves an acetylene conversion of up to 90% at 220 °C under a gas hourly space velocity of 300 h^–1, significantly surpassing the performance of the benchmark 0.25% Au/AC catalyst. This proof-of-concept study reveals the fundamental mechanisms driving the superior performance of carbon catalysts with curved nanostructures and presents a straightforward, environmentally friendly method for large-scale production of carbon materials with precisely controlled nanostructures. It highlights the potential for commercializing metal-free carbon catalysts in acetylene hydrochlorination and related heterogenous catalytic reactions.