期刊
CHEMELECTROCHEM
卷 6, 期 13, 页码 3507-3515出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/celc.201900659
关键词
boron-doped diamond; scanning electrochemical microscopy; water splitting; surface chemistry; reactive intermediates
资金
- Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub - U.S. Department of Energy, Office of Science, Basic Energy Sciences
Boron-doped diamond (BDD) electrodes are widely used in electrochemical sensing and water purification owing to their chemical and structural stability under harsh reaction conditions. Water oxidation at BDD electrodes is known to produce reactive oxygen species, but the discharged and surface chemistries involved in these processes have not been studied in depth. Here, we present scanning electrochemical microscopy (SECM) studies of electrogenerated intermediates and products formed on sp(2) carbon-containing BDD electrodes that display stark differences in their reactivity as a function of electrolyte type and pH during water oxidation. The most reactive and abundant species discharged from the electrode were observed at pH 11 in sulfate electrolyte. With the surface interrogation mode of SECM, two kinetically distinct surface intermediates were clearly distinguished, with one forming two orders of magnitude faster than the other but displaying a slower desorption rate. The surface coverage of these species was estimated in the range of 4-7x10(-5) mol/cm(2) for the first, and 3-4.4x10(-5) mol/cm(2) for the second one. SECM imaging suggested that regions of increased product evolution have decreased electron transfer kinetics and limited surface sites for intermediate binding. This work establishes methods for studying highly reactive intermediates found in BDD and paves the way for the inspection of other interfaces where solvolysis impacts their reactivity and evolution.
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