Activating Metal Oxides Nanocatalysts for Electrocatalytic Water Oxidation by Quenching-Induced Near-Surface Metal Atom Functionality

Abstract

Developing a reliable strategy for the modulation of the texture, composition, and electronic structure of electrocatalyst surfaces is crucial for electrocatalytic performance, yet still challenging. Herein, we develop a facile and universal strategy, quenching, to precisely tailor the surface chemistry of metal oxide nanocatalysts by rapidly cooling them in a salt solution. Taking NiMoO 4 nanocatalysts an example, we successfully produce the quenched nanocatalysts offering a greatly reduced oxygen evolution reaction (OER) overpotential by 85 mV and 135 mV at 10 mA cm −2 and 100 mA cm −2 respectively. Through detailed characterization studies, we establish that quenching induces the formation of numerous disordered stepped surfaces and the near-surface metal ions doping, thus regulating the local electronic structures and coordination environments of Ni, Mo, which promotes the formation of the dualsite active and thereby affords a low energy pathway for OER. This quenching strategy is also successfully applied to a number of other metal oxides, such as spinel-type Co 3 O 4 , Fe 2 O 3 , LaMnO 3 , and CoSnO 3 , with similar surface modifications and gains in OER activity. Our finding provides a new inspiration to activate metal oxide catalysts and extends the use of quenching chemistry in catalysis.

Heterostructured FeNi hydroxide for effective electrocatalytic oxygen evolution

“…This increase is corroborated by the decrease in the ratio of Ni 2+ /Ni 3+ from 1.87 to 1.53, indicative of oxidation of Ni 2+ . 42 In addition, we also compared FeNi/Ni HS with other transition…”

The Perfect Imperfections in Electrocatalysts

“…The schematic design of 0D and part of 3D defects are adapted from Zheng et al Joule 2018, 2, 2551. [2] solutions, [17] surface changes made by pretreatment and etching, [6] the 2D cavities created by etching, [18] atom/ion interstitials or vacancies to form undercoordinated sites, [19] and creation of low or high-angle GBs. [20] At nanoscale dimensions, the existence of defects is inevitable but the literature is mostly limited in demonstrating the mechanism by which these intrinsic defects can control the chemical reactivity of the catalyst materials.…”

Intermolecular Energy Gap‐Induced Formation of High‐Valent Cobalt Species in CoOOH Surface Layer on Cobalt Sulfides for Efficient Water Oxidation

“…Generally, these kinds of electrocatalysts, known as pre‐catalysts, will undergo an irreversible structural reconstruction by forming metal oxyhydroxides on their surfaces during OER process. Consequently, the obtained hybrids with the core–shell structure have been widely regarded as the “true electrocatalysts” towards OER [13–17] . More interestingly, these reconstructed active metal oxyhydroxide hybrids usually display much higher OER performances than their bulk counterparts synthesized through conventional methods.…”