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 catalyt...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℃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.展开更多
It is generally acknowledged in heterogeneous catalysis that hydrogenation follows the so-called Horiuti-Polanyi(HP) mechanism. In this work, a thorough investigation of the mechanism of hydrogenation of hydroxyl grou...It is generally acknowledged in heterogeneous catalysis that hydrogenation follows the so-called Horiuti-Polanyi(HP) mechanism. In this work, a thorough investigation of the mechanism of hydrogenation of hydroxyl groups and O catalyzed by a series of transition metals was carried out through density functional theory calculations, as surface hydroxyls and O are very common species in many catalytic systems. It is found that different metal catalysts exhibit different mechanisms. On some metal catalysts, the non-HP mechanism is preferred, whereas the classic HP mechanism is favored on other catalysts. Detailed analyses of the metal-dependent mechanism shows that the activity toward the dissociation of H2 decides which mechanism is preferred. On active catalysts, such as Ni and Pt, H2 prefers to dissociate with strong H adsorption energies, which lead to the classic HP mechanism being favored. On inactive surfaces, on the other hand, the adsorption of H is weak, which results in the non-HP mechanism being preferred. The parameter η, which is a structural descriptor, was defined to understand the different mechanisms.展开更多
文摘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℃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.
基金supported by the National Natural Science Foundation of China(21673072,21333003,and 91845111)~~
文摘It is generally acknowledged in heterogeneous catalysis that hydrogenation follows the so-called Horiuti-Polanyi(HP) mechanism. In this work, a thorough investigation of the mechanism of hydrogenation of hydroxyl groups and O catalyzed by a series of transition metals was carried out through density functional theory calculations, as surface hydroxyls and O are very common species in many catalytic systems. It is found that different metal catalysts exhibit different mechanisms. On some metal catalysts, the non-HP mechanism is preferred, whereas the classic HP mechanism is favored on other catalysts. Detailed analyses of the metal-dependent mechanism shows that the activity toward the dissociation of H2 decides which mechanism is preferred. On active catalysts, such as Ni and Pt, H2 prefers to dissociate with strong H adsorption energies, which lead to the classic HP mechanism being favored. On inactive surfaces, on the other hand, the adsorption of H is weak, which results in the non-HP mechanism being preferred. The parameter η, which is a structural descriptor, was defined to understand the different mechanisms.
