Abstract
The incorporation of defects, such as vacancies, into functional materials could substantially tailor their intrinsic properties. Progress in vacancy chemistry has enabled advances in many technological applications, but creating new type of vacancies in existing material system remains a big challenge. We show here that ionized nitrogen plasma can break bonds of iron-carbon-nitrogen-nickel units in nickel-iron Prussian blue analogues, forming unconventional carbon-nitrogen vacancies. We study oxygen evolution reaction on the carbon-nitrogen vacancy-mediated Prussian blue analogues, which exhibit a low overpotential of 283 millivolts at 10 milliamperes per square centimeter in alkali, far exceeding that of original Prussian blue analogues and previously reported oxygen evolution catalysts with vacancies. We ascribe this enhancement to the in-situ generated nickel-iron oxy(hydroxide) active layer during oxygen evolution reaction, where the Fe leaching was significantly suppressed by the unconventional carbon-nitrogen vacancies. This work opens up opportunities for producing vacancy defects in nanomaterials for broad applications.
Highlights
The incorporation of defects, such as vacancies, into functional materials could substantially tailor their intrinsic properties
A new type of vacancy created in Prussian blue analogues (PBAs) would trigger the change of local electronic environment, which subsequently leads to regions of enhanced energetics for catalysis
The NiMoO4 was dispersed in a K4Fe(CN)63H2O aqueous solution under ultrasonication for 2 h, which templates the formation of one-dimensional K2NiFe(CN)[6] Prussian blue analogues (PBAs; Supplementary Fig. 1)
Summary
The incorporation of defects, such as vacancies, into functional materials could substantially tailor their intrinsic properties. We study oxygen evolution reaction on the carbon-nitrogen vacancy-mediated Prussian blue analogues, which exhibit a low overpotential of 283 millivolts at 10 milliamperes per square centimeter in alkali, far exceeding that of original Prussian blue analogues and previously reported oxygen evolution catalysts with vacancies We ascribe this enhancement to the in-situ generated nickel-iron oxy(hydroxide) active layer during oxygen evolution reaction, where the Fe leaching was significantly suppressed by the unconventional carbon-nitrogen vacancies. The most common defect observed is vacancy, and typically, vacancy engineering can lead to substantial structural perturbations in catalysts, with the capability to tailor surface electronegativity, charge concentration, and redistribution[18,19] Once overcoming their formation energy, both anion and/or cation vacancies can be formed, giving diverse vacancy defects like oxygen[21,22], sulfur[20,23], iodine[24], nickel[25], iron[26], and sometimes dual vacancies[27,28]. Our work widens the family of vacancy defects, which provides access to enhanced functionalities of PBA materials for various applications
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