Amorphous Cobalt–Iron Hydroxide Nanosheet Electrocatalyst for Efficient Electrochemical and Photo‐Electrochemical Oxygen Evolution

Abstract

Finding efficient electrocatalysts for oxygen evolution reaction (OER) that can be effectively integrated with semiconductors is significantly challenging for solar‐driven photo‐electrochemical (PEC) water splitting. Herein, amorphous cobalt–iron hydroxide (CoFeH) nanosheets are synthesized by facile electrodeposition as an efficient catalyst for both electrochemical and PEC water oxidation. As a result of the high electrochemically active surface area and the amorphous nature, the optimized amorphous CoFeH nanosheets exhibit superior OER catalytic activity in alkaline environment with a small overpotential (280 mV) to achieve significant oxygen evolution (j = 10 mA cm−2) and a low Tafel slope (28 mV dec−1). Furthermore, CoFeH nanosheets are simply integrated with BiVO4 semiconductor to construct CoFeH/BiVO4 photoanodes that exhibit a significantly enhanced photocurrent density of 2.48 mA cm−2 (at 1.23 V vs reversible hydrogen electrode (RHE)) and a much lower onset potential of 0.23 V (vs RHE) for PEC‐OER. Careful electrochemical and optical studies reveal that the improved OER kinetics and high‐quality interface at the CoFeH/BiVO4 junction, as well as the excellent optical transparency of CoFeH nanosheets, contribute to the high PEC performance. This study establishes amorphous CoFeH nanosheets as a highly competitive candidate for electrochemical and PEC water oxidation and provides general guidelines for designing efficient PEC systems.

Ultrathin Porous NiFeV Ternary Layer Hydroxide Nanosheets as a Highly Efficient Bifunctional Electrocatalyst for Overall Water Splitting

“…Hence, the discovery of earth‐abundant, low‐cost, and high activity bifunctional electrocatalysts to achieve low energy‐intensive water electrolysis is still highly desired. A wide range of earth abundant catalytic materials with different morphologies, structure or loaded on various substrates have been developed for OER and HER, including transition metal oxides/hydroxides, carbides, and phosphides . Nevertheless, as stated in recent report, metal chalcogenides, nitrides, and phosphides are very sensitive in the strongly oxidizing OER conditions .…”

Electroactive Edge‐Site‐Enriched α‐Co0.9Fe0.1(OH)x Nanoplates for Efficient Overall Water Splitting

“…[17] Besides, it is widely accepted that the edge sites of MoS 2 are highly catalytically active and are thus preferred at the catalyst surface over the MoS 2 basal planes, which are inert. Because it can provide larger active surface area and interfacial contact area of electrode/electrolyte, facilitating the interfacial charge transfer of reaction.…”

Recent Progress on Multimetal Oxide Catalysts for the Oxygen Evolution Reaction

“…www.advenergymat.de nanosheets, [179] and hollow structures [142] have been applied to amorphous multimetal oxides, resulting in outstanding performance as listed in Table 3. To increase the mass activity, Yang et al devised a nanoporous structure, which was obtained by applying anodic galvanostatic treatments to an amorphous Co-Ni oxide synthesized via electrodeposition.…”

“…Reproduced with permission. [179] Copyright 2017, Wiley-VCH. b) Synthesis process, c) TEM image, and (inset) SAED pattern of Ni-Co amorphous double hydroxide nanocages.…”

“…Liu et al utilized the nanosheet morphology to enhance the efficiency of Co-Fe hydroxide. [179] During the electrodeposition synthesis process, NO 3 − ions were cathodically reduced to NH 4 + ions, yielding OH − ions. These OH − ions were coprecipitated slowly with Co 2+ and Fe 3+ ions to produce amorphous Co-Fe nanosheets (Co:Fe = 1:1) with uniform metal distribution.…”