催化学报 ›› 2017, Vol. 38 ›› Issue (9): 1621-1628.DOI: 10.1016/S1872-2067(17)62760-8

• 论文 • 上一篇    下一篇

DFT计算研究碱性条件下γ-FeOOH(010)上氧析出反应机理

Miru Tang, Qingfeng Ge   

  1. 南伊利诺伊大学化学与生物化学系, 卡本代尔 IL 62901, 美国
  • 收稿日期:2016-11-30 修回日期:2016-12-26 出版日期:2017-09-18 发布日期:2017-09-06
  • 通讯作者: Qingfeng Ge
  • 基金资助:

    美国国家科学基金会化学生物环境及传递系统项目(CBET-1438440).

Mechanistic understanding on oxygen evolution reaction on γ-FeOOH (010) under alkaline condition based on DFT computational study

Miru Tang, Qingfeng Ge   

  1. Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA
  • Received:2016-11-30 Revised:2016-12-26 Online:2017-09-18 Published:2017-09-06
  • Contact: 10.1016/S1872-2067(17)62760-8
  • Supported by:

    This work was supported by the Chemical, Biological, Environmental, and Transport Systems (CBET) program of US National Science Foundation (CBET-1438440).

摘要:

一个高效经济的氧析出反应(OER)催化剂是大范围应用太阳能转化能源的关键.在众多有潜力的OER催化剂中,金属氢氧化物,尤其是FeOOH表现出很高的OER活性.我们采用DFT+U研究了γ-FeOOH(010)表面上OER反应机理;得到了OH-和空穴对的化学势,并将OH-阴离子包含在反应机理中,以此来说明碱性条件下阳极的OER过程.随后分析了催化剂中OH-,O-和Fe-终止的表面上OER反应路径.含有OH-,O-终止的表面上,O2分子是通过OH与表面氧物种(-OH*和-O*)反应,或二个表面氧物种相结合而形成的.在Fe-终止的表面上,O2只能通过首先在Fe位上吸附OH而形成.不同形式表面上O2析出的化学势决定步骤取决于每个路径中基元步骤自由能的变化.结果表明,O2的形成需要重建表面Fe位,因此,有利于部分暴露Fe位的条件也将促进O2的形成.

关键词: 水分解, 氧析出反应, DFT+U, 氢氧化铁

Abstract:

An efficient and economical oxygen evolution reaction (OER) catalyst is critical to the widespread application of solar energy to fuel conversion. Among many potential OER catalysts, the metal oxy-hydroxides, especially FeOOH, show promising OER reactivity. In the present work, we performed a DFT + U study of the OER mechanism on the γ-FeOOH (010) surface. In particular, we established the chemical potential of the OH- and hole pair and included the OH- anion in the reaction pathway, accounting to the alkaline conditions of anodic OER process. We then analyzed the OER pathways on the surface with OH-, O-and Fe-terminations. On the surface with OH-and O-terminations, the O2 molecule could form from either OH reacting with the surface oxygen species (-OH* and -O*) or the combination of two surface oxygen species. On the Fe-terminated surface, O2 can only form by adsorbing OH on the Fe sites first. The potential-limiting step of the oxygen evolution with different surface terminations was determined by following the free-energy change of the elementary steps along each pathway. Our results show that oxygen formation requires recreating the surface Fe sites, and consequently, the condition that favors the partially exposed Fe sites will promote oxygen formation.

Key words: Water splitting, Oxygen evolution reaction, DFT + U, Iron oxyhydroxides