期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 114, 期 8, 页码 1795-1800出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1612106114
关键词
reaction mechanism; electrocatalysis; copper; QM metadynamics; free-energy reaction barriers
资金
- Joint Center for Artificial Photosynthesis, a Department of Energy Innovation Hub through the Office of Science of the US Department of Energy [DE-SC0004993]
NA critical step toward the rational design of new catalysts that achieve selective and efficient reduction of CO2 to specific hydrocarbons and oxygenates is to determine the detailed reaction mechanism including kinetics and product selectivity as a function of pH and applied potential for known systems. To accomplish this, we apply ab initio molecular metadynamics simulations (AIMD) for the water/Cu(100) system with five layers of the explicit solvent under a potential of -0.59 V [ reversible hydrogen electrode (RHE)] at pH 7 and compare with experiment. From these free-energy calculations, we determined the kinetics and pathways for major products (ethylene and methane) and minor products (ethanol, glyoxal, glycolaldehyde, ethylene glycol, acetaldehyde, ethane, and methanol). For an applied potential (U) greater than -0.6 V (RHE) ethylene, the major product, is produced via the Eley-Rideal (ER) mechanism using H2O + e(-). The rate-determining step (RDS) is C-C coupling of two CO, with Delta G not asymptotic to = 0.69 eV. For an applied potential less than -0.60 V (RHE), the rate of ethylene formation decreases, mainly due to the loss of CO surface sites, which are replaced by H*. The reappearance of C2H4 along with CH4 at U less than -0.85 V arises from *CHO formation produced via an ER process of H* with nonadsorbed CO (a unique result). This *CHO is the common intermediate for the formation of both CH4 and C2H4. These results suggest that, to obtain hydrocarbon products selectively and efficiency at pH 7, we need to increase the CO concentration by changing the solvent or alloying the surface.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据