请选择 进入手机版 | 继续访问电脑版
搞化学,就上化学吧!·有朋自远方来不亦乐乎?欢迎新人送金币,点击进入!·社区工具·最新主题
热爱我们的家园,分享我们的生活,畅想我们的未来。

☆麦兜☆

 找回密码
 加入我们

QQ登录

只需一步,快速开始

☆麦兜☆ 门户 文章 捷报 查看内容

[JACS] Computational and Experimental Study of the Mechanism of Hydrogen Generat

2014-4-23 00:03| 发布者: Mcdull| 查看: 2066| 评论: 0|原作者: yangxz|来自: 捷报频传

摘要: Remarks: 跟Martin Head-Gordon、 Chris Chang和Jeff Long合作的一篇文章。主要是针对Chris Chang和Jeff Long大约两年前在Nature上发表的2+电催化分解水产氢反应的机理研究。这个工作其实从2010年就开始做,但因为需 ...
Eric J. Sundstrom, Xinzheng Yang, Hemamala I. Karunadasa, Sara V. Thoi, Christopher J. Chang, Jeffrey R. Long, Martin Head-Gordon*

J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/ja210949r
Publication Date (Web): February 22, 2012
Copyright © 2012 American Chemical Society

Abstract:
We investigate the mechanism for the electrocatalytic generation of hydrogen from water by the molecular molybdenum-oxo complex, [(PY5Me2)MoO]2+ (PY5Me2 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine). Computational and experimental evidence suggests that the electrocatalysis consists of three distinct electrochemical reductions, which precede the onset of catalysis. Cyclic voltammetry studies indicate that the first two reductions are accompanied by protonations to afford the Mo-aqua complex, [(PY5Me2)Mo(OH2)]+. Calculations support hydrogen evolution from this complex upon the third reduction, via the oxidative addition of a proton from the bound water to the metal center and finally an α-H abstraction to release hydrogen. Calculations further suggest that introducing electron-withdrawing substituents such as fluorides in the para positions of the pyridine rings can reduce the potential associated with the reductive steps, without substantially affecting the kinetics. After the third reduction, there are kinetic bottlenecks to the formation of the Mo-hydride and subsequent hydrogen release. Computational evidence also suggests an alternative to direct α-H abstraction as a mechanism for H2 release which exhibits a lower barrier. The new mechanism is one in which a water acts as an intramolecular proton relay between the protons of the hydroxide and the hydride ligands. The calculated kinetics are in reasonable agreement with experimental measurements. Additionally, we propose a mechanism for the stoichiometric reaction of [(PY5Me2)Mo(CF3SO3)]+ with water to yield hydrogen and [(PY5Me2)MoO]2+ along with the implications for the viability of an alternate catalytic cycle involving just two reductions to generate the active catalyst.

http://pubs.acs.org/doi/abs/10.1021/ja210949r

Remarks: 跟Martin Head-Gordon、 Chris Chang和Jeff Long合作的一篇文章。主要是针对Chris Chang和Jeff Long大约两年前在Nature上发表的[(PY5Me2)MoO]2+电催化分解水产氢反应的机理研究。这个工作其实从2010年就开始做,但因为需要等一些实验数据,合作人也比较多,所以文章拖到现在才发表。

相关分类

手机版|Archiver|chem8.org ( 闽ICP备17001654号 )  

闽公网安备 35020602000685号

GMT+8, 2017-5-25 12:30 , Processed in 0.087928 second(s), 23 queries .

Powered by Discuz! X2.5

© 2001-2012 Comsenz Inc.

回顶部