Etched High-Entropy Prussian Blue Analogues as Trifunctional Catalysts for Water, Ethanol, and Urea Electrooxidation

NH3 & BULL;H2O-etchedhigh-entropy PBAsare constructed to function as a trifunctional catalyst toward electrocatalyticOER, EOR, and UOR. The introduction of high-entropy and high specific surfaceareainto Prussian blue analogues (PBAs) has yet to create interest inthe field of electrocatalytic small-molecule oxidation reactions.Herein, we synthesize a novel class of high-entropy (HE) PBAs witha high specific surface area via a simple NH3 & BULL;H2O-etching strategy and systematically investigate the electrocatalyticperformance of HE-PBA toward electrocatalytic water, ethanol, andurea oxidation reactions. Importantly, the NH3 & BULL;H2O-etched HE-PBA (denoted as HE-PBA-e) demonstrated enhancedelectrocatalytic performance toward small-molecule oxidation comparedto the pristine HE-PBA, reaching 10 mA cm(-2) withpotentials of 1.56, 1.41, and 1.37 V for the oxygen evolution reaction(OER), ethanol oxidation reaction (EOR), and urea oxidation reaction(UOR), respectively. Deep characterizations suggest that the NH3 & BULL;H2O etching treatment not only creates richnanopores to enlarge the surface area and boosts the mass transportand electron transfer but also facilitates the formation of high-valencemetal oxides to improve the intrinsic activity. This demonstrationof how systematically increasing the high oxidation state of metalswill serve as a governing principle for the rational design of moreadvanced HE-PBAs toward the electrooxidation of small molecules.

Automated summary

NH3 & BULL;H2O-etched high-entropy PBAs are used as trifunctional catalysts for electrocatalytic OER, EOR, and UOR. The NH3 & BULL;H2O etching treatment enhances the electrocatalytic performance of high-entropy PBAs, achieving higher current densities for small-molecule oxidation reactions. This study demonstrates the importance of increasing the high oxidation state of metals for the rational design of advanced high-entropy PBAs for electrooxidation of small molecules.