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Inexpensive Amorphous Fe III Oxo‐/Hydroxide as Highly Active and Ultradurable Electrocatalyst for Water Electrolysis
Author(s) -
Mathi Selvam,
Jayabharathi Jayaraman
Publication year - 2021
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.202001547
Subject(s) - overpotential , tafel equation , electrocatalyst , oxygen evolution , electrolysis of water , water splitting , electrolysis , chemistry , catalysis , nanoparticle , chemical engineering , alkaline water electrolysis , amorphous solid , inorganic chemistry , materials science , nanotechnology , electrode , electrochemistry , crystallography , photocatalysis , biochemistry , engineering , electrolyte
Developing highly active, cost‐effective, and robust electrocatalysts for the oxygen evolution reaction (OER) still remains a crucial challenge for enhancing the conversion of sustainable energy resources. The performances of existing electrocatalysts is restricted by low electronic conductivity and the limited amount of active sites. Herein, newly synthesized Fe III OH nanoparticles (NPs) are shown to be efficient and durable electrocatalysts for the OER reaction. Fe III OH NP‐coated nickel foam (Fe III OH NPs/NF) operates at an overpotential of 300 mV (@10 mA cm −2 ) with excellent stability even after 30 h and shows higher stability relative to a cell voltage of 1.55 V in alkaline media, which is substantially lower than the commercial electrocatalyst IrO 2 (1.61 V). The Fe III OH NPs/NF overpotential of 300 mV at 10 mA cm −2 is 89 and 127 mV lower than IrO 2 /NF (389 mV) and NF (427 mV), respectively. The Tafel slope of Fe III OH NPs/NF (104 mV dec −1 ) is lower than IrO 2 /NF (164 mV dec −1 ) and NF (199 mV dec −1 ). The calculated turnover frequency (TOF) of Fe III OH NPs (0.0128 s −1 ) is approximately five times higher than that of the IrO 2 catalyst (0.0089 s −1 ) at 1.60 V. This reflects that the Fe III OH NP catalyst is intrinsically active, giving outstanding OER performances and showing satisfactory kinetics to overcome the sluggish water oxidation rate. Solar water electrolysis shows continuous evolution of oxygen and hydrogen gas at the anode and cathode, respectively, at 1.55 V. The amount of hydrogen generated during solar water electrolysis was calculated as 3.22 mmol h −1 cm −2 , which is close to the coulombic efficiency at 1.55 V. This demonstration develops the hope for superior exploration of Fe III OH NPs/NF toward the expansion of real and large‐scale hydrogen production with the lowest price.