Mistry Kallum, Snowden Henry, Darling George R, Hodgson Andrew
Surface Science Research Centre and Department of Chemistry, University of Liverpool, Liverpool L69 3BX, U.K.
J Phys Chem C Nanomater Interfaces. 2024 Jul 30;128(31):13025-13033. doi: 10.1021/acs.jpcc.4c04091. eCollection 2024 Aug 8.
We describe the hydroxyl and mixed hydroxyl-water structures formed on a stepped copper surface following the reaction of adsorbed O with water at a low temperature and compare them to the structures found previously on plane copper surfaces. Thermal desorption profiles, STM, and low-energy electron diffraction show that water reacts with O at temperatures below 130 K on Cu(511). Two well-defined phases appear as the OH/HO layer is heated to desorb excess water, a 1OH:1HO phase and a pure OH phase. The 1OH:1HO structure consists of 1D chains binding across two adjacent copper steps, with a double period along the step. Electronic structure calculations show that the structure has a zigzag chain of water along the terrace, stabilized by hydrogen bonds to OH groups adsorbed in the step bridge sites. This structure binds OH in its favored site and is similar to the structure observed on other open faces of Cu and Ni, suggesting that this structural arrangement may be common on other surfaces that have steps or rows of close packed metal atoms. The hydroxyl/water chains decompose at 210 K to leave OH adsorbed in the Cu step bridge site, with some forming H-bonded trimers that bridge between two Cu steps. Heating the surface causes hydroxyl to disproportionate near 300 K, desorbing water to leave chemisorbed O.
我们描述了在低温下吸附的氧与水反应后在阶梯状铜表面形成的羟基和混合羟基 - 水结构，并将它们与先前在平面铜表面发现的结构进行比较。热脱附谱、扫描隧道显微镜（STM）和低能电子衍射表明，在Cu(511)上，水在130 K以下的温度与氧反应。当OH/HO层被加热以解吸过量的水时，出现两个明确的相，即1OH:1HO相和纯OH相。1OH:1HO结构由跨越两个相邻铜阶梯的一维链组成，沿阶梯方向具有双周期。电子结构计算表明，该结构在台面上有一条锯齿状的水链，通过与吸附在阶梯桥位的OH基团形成氢键而稳定。这种结构将OH结合在其有利的位置，并且与在Cu和Ni的其他开放表面上观察到的结构相似，这表明这种结构排列在其他具有阶梯或紧密堆积金属原子行的表面上可能很常见。羟基/水链在210 K时分解，留下吸附在铜阶梯桥位的OH，其中一些形成在两个铜阶梯之间桥连的氢键三聚体。加热表面会使羟基在300 K附近发生歧化反应，解吸水并留下化学吸附的氧。
