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Laser Fragmentation‐Induced Defect‐Rich Cobalt Oxide Nanoparticles for Electrochemical Oxygen Evolution Reaction
Author(s) -
Yu Mingquan,
Waag Friedrich,
Chan Candace K.,
Weidenthaler Claudia,
Barcikowski Stephan,
Tüysüz Harun
Publication year - 2020
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201903186
Subject(s) - tafel equation , cobalt , cobalt oxide , materials science , oxygen evolution , nanoparticle , x ray photoelectron spectroscopy , catalysis , water splitting , oxide , chemical engineering , electrochemistry , inorganic chemistry , chemistry , photochemistry , photocatalysis , nanotechnology , electrode , biochemistry , engineering , metallurgy
Sub‐5 nm cobalt oxide nanoparticles are produced in a flowing water system by pulsed laser fragmentation in liquid (PLFL). Particle fragmentation from 8 nm to 4 nm occurs and is attributed to the oxidation process in water where oxidative species are present and the local temperature is rapidly elevated under laser irradiation. Significantly higher surface area, crystal phase transformation, and formation of structural defects (Co 2+ defects and oxygen vacancies) through the PLFL process are evidenced by detailed structural characterizations by nitrogen physisorption, electron microscopy, synchrotron X‐ray diffraction, and X‐ray photoelectron spectroscopy. When employed as electrocatalysts for the oxygen evolution reaction under alkaline conditions, the fragmented cobalt oxides exhibit superior catalytic activity over pristine and nanocast cobalt oxides, delivering a current density of 10 mA cm −2 at 369 mV and a Tafel slope of 46 mV dec −1 , which is attributed to a larger exposed active surface area, the formation of defects, and an increased charge transfer rate. The study provides an effective approach to engineering cobalt oxide nanostructures in a flowing water system, which shows great potential for sustainable production of active cobalt catalysts.