CoOOH Nanosheets with High Mass Activity for Water Oxidation

Abstract

Endowing transition‐metal oxide electrocatalysts with high water oxidation activity is greatly desired for production of clean and sustainable chemical fuels. Here, we present an atomically thin cobalt oxyhydroxide (γ‐CoOOH) nanosheet as an efficient electrocatalyst for water oxidation. The 1.4 nm thick γ‐CoOOH nanosheet electrocatalyst can effectively oxidize water with extraordinarily large mass activities of 66.6 A g−1, 20 times higher than that of γ‐CoOOH bulk and 2.4 times higher than that of the benchmarking IrO2 electrocatalyst. Experimental characterizations and first‐principles calculations provide solid evidence to the half‐metallic nature of the as‐prepared nanosheets with local structure distortion of the surface CoO6−x octahedron. This greatly enhances the electrophilicity of H2O and facilitates the interfacial electron transfer between Co ions and adsorbed ‐OOH species to form O2, resulting in the high electrocatalytic activity of layered CoOOH for water oxidation.

Selectively Etching Vanadium Oxide to Modulate Surface Vacancies of Unary Metal–Based Electrocatalysts for High‐Performance Water Oxidation

“…Interestingly, we directly synthesized CoOOH according to the previous report, [20] and Co 0.5 (V 0.5 ) shows better OER performance than the direct-synthesized CoOOH ( Figure S21, Supporting Information), further confirming the electrocatalytic improvement by oxygen vacancy modulated by etching vanadium oxides. Interestingly, we directly synthesized CoOOH according to the previous report, [20] and Co 0.5 (V 0.5 ) shows better OER performance than the direct-synthesized CoOOH ( Figure S21, Supporting Information), further confirming the electrocatalytic improvement by oxygen vacancy modulated by etching vanadium oxides.…”

“…Remarkable current stability is exhibited by Co 0.5 (V 0.5 ) at 350 mV overpotential ( Figure S14, Supporting Information), without any distinct long-term structural changes, after a minimum duration of 9 h, according to TEM studies ( Figure S15, Supporting Information). In fact, to the best of our knowledge, Co 0.5 (V 0.5 ) appears to perform even better than the most efficient unary metal-(CoOOH nanosheet [20] ) and bimetal-based (CoMn LDH [6] ) electrocatalysts, and functions as well as the best OER multimetal electrocatalyst reported so far (FeCoWOOH). Figure 4b shows the Tafel slopes, ranging between 56 and 64 mV dec −1 (average values) without any clear trend, corresponding to different compositions Co x (V 1−x ) in 1 m KOH, as a function of the Co content (x).…”

Unraveling Geometrical Site Confinement in Highly Efficient Iron‐Doped Electrocatalysts toward Oxygen Evolution Reaction

“…[48] The half-full configuration in crystal field diagrams of Fe 3+ (Oh) /Fe 3+ (Td) and the energetical similarity in Δ oct and Δ tet resulted in an identical electronic structure, and a theoretical study of absorption spectra in varying the corresponding crystal field stabilization energies predicted this argument as well. In the case of cobalt ions, for the reason that t 2g orbitals were related to the π-bonding with oxygen-related intermediate, [50,51] a full occupation of t 2g orbitals in Co 3+ (Oh) suppressed the adsorption of intermediates and the reaction of active species for OER. In the case of cobalt ions, for the reason that t 2g orbitals were related to the π-bonding with oxygen-related intermediate, [50,51] a full occupation of t 2g orbitals in Co 3+ (Oh) suppressed the adsorption of intermediates and the reaction of active species for OER.…”

Effective Construction of High-quality Iron Oxy-hydroxides and Co-doped Iron Oxy-hydroxides Nanostructures: Towards the Promising Oxygen Evolution Reaction Application

“…Importantly, the overpotential of Co 0.54 Fe 0.46 OOH was 390 mV (at a current density of 10 mA/cm2), which was lower than those of FeOOH1 (750 mV), FeOOH2 (530 mV), FeOOH3 (630 mV) electrodes. Notably, in comparison with the behavior of most metal oxy-hydroxide nanomaterials in alkaline electrolytes30313233, the overpotential was promising (listed in Supplementary Table S2). …”