Synthesis of Co(II)-Fe(III) Hydroxide Nanocones with Mixed Octahedral/Tetrahedral Coordination toward Efficient Electrocatalysis

Abstract

Layered double hydroxides (LDHs) with di-/trivalent metal cations are considered as one of the most promising materials for highperformance electrocatalysts. On the other hand, α-type hydroxides, with cations in controllable mixed octahedral/tetrahedral coordination, have been rarely investigated. Here, we report a general approach to prepare novel Co(II) 4 Fe(III) 1 hydroxide nanocones (NCs) with both features of α-type mixed octahedral(O h )/tetrahedral(T d ) coordination and LDH-analogous mixed di-/trivalences, i.e., mix-O h /T d LDH. Specifically, Co(II) 4 Fe(III) 1 hydroxide NCs in such a mix-O h /T d LDH structure were synthesized and tested as electrocatalysts for the oxygen evolution reaction (OER) and were found to be capable of delivering a current density of 10 mA cm −2 at a low overpotential of ∼263 mV, with a remarkable turnover frequency (TOF) that is 1 order of magnitude higher than that of Co(II) 4 Fe(III) 1 LDH nanoplatelets with octahedral coordination only. It was also found that the NCs exhibited a very high electrochemical active surface area (ECSA) due to their hollow conical morphology and large interlayer spacing. More importantly, spectroscopic characterizations of the samples after the electrochemical reaction, associated with density functional theory (DFT) calculations, proved that mix-O h /T d LDH NCs are more likely to form oxyhydroxides with cobalt and iron toward higher oxidation states. As a result, the ability to adsorb oxygen free radicals may be significantly enhanced and the energy barrier of OER is substantially lowered.

A metal-free photocatalyst for highly efficient hydrogen peroxide photoproduction in real seawater

“…S22a ). The smaller semicircle for PM-CDs-30 indicates a faster electron transfer than others, suggesting that PM-CDs-30 possess the best migration property 30 . Time-dependent photo-response curves of these samples are tested with intermittent visible light ( λ ≥ 420 nm) at open-circuit voltage in seawater (Fig.…”

Unveiling the Occurrence of Co(III) in NiCo Layered Electroactive Hydroxides: The Role of Distorted Environments

“…Then, this unique and inherently complex structure, herein named "meta layered hydroxide"( mLH), combines in a single phase the inherentf unctionalities of the layered double hydroxides and the simonkolleite-like layered basic salts. [87]…”

“…In fact, the current experimental and computational findings, mutually confirm the occurrence of a new type of layered structure, where two different environments (octahedral and tetrahedral) and two oxidation states (divalent and trivalent) coexist. Then, this unique and inherently complex structure, herein named “ meta layered hydroxide” (mLH), combines in a single phase the inherent functionalities of the layered double hydroxides and the simonkolleite‐like layered basic salts [87] …”

Anchoring Active Sites by Pt2FeNi Alloy Nanoparticles on NiFe Layered Double Hydroxides for Efficient Electrocatalytic Oxygen Evolution Reaction

“…With the aggravation of energy crisis and environmental pollution, it is significant to seek sustainable and eco‐friendly energy. [ 1–3 ] Oxygen evolution reaction (OER) has attracted extensive research interests as a kinetically sluggish process in water splitting [ 4–6 ] and metal air batteries. [ 7–9 ] In the electrocatalytic water splitting, compared with hydrogen evolution reaction (HER), OER demands a higher overpotential to drive the complex four proton coupled electron transfers and the formation of oxygen‐oxygen bond.…”