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Gold Doping in a Layered Co‐Ni Hydroxide System via Galvanic Replacement for Overall Electrochemical Water Splitting
Author(s) -
Sultana Ummul K.,
Riches James D.,
O'Mullane Anthony P.
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201804361
Subject(s) - oxygen evolution , materials science , water splitting , electrochemistry , electrolysis , electrolysis of water , galvanic cell , chemical engineering , alkaline water electrolysis , hydroxide , electrolyte , bifunctional , electrode , inorganic chemistry , metallurgy , catalysis , chemistry , biochemistry , photocatalysis , engineering
The development of active yet stable bifunctional materials to produce hydrogen and oxygen via electrochemical water splitting is an ongoing challenge. Here, a system based on electrodeposited Ni(OH) 2 and Co(OH) 2 containing highly distributed gold nanoparticles at less than 0.25 at% to facilitate the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline conditions is developed. The key aspect is using galvanic replacement to deposit gold on a layer of electrodeposited Co(OH) 2 prior to electrodepositing Ni(OH) 2 . The fabrication of a composite system based on Co(OH) 2 ‐Au‐Ni(OH) 2 is required for optimal activity for both the HER and OER. The composite is characterized with helium ion microscopy, transmission electron microscopy, depth profiling X‐ray photoelectron microscopy, and a variety of electrochemical techniques. This material exceeds the activity of Pt for the HER at current densities greater than 40 mA cm −2 and is stable for both reactions for prolonged periods of electrolysis. In a two‐electrode configuration, current densities greater than 175 mA cm −2 for overall water splitting could be readily achieved at an applied voltage of 1.90 V in a commercially relevant electrolyte of 6 m NaOH.