Tuning Metal Elements in Open Frameworks for Efficient Oxygen Evolution and Oxygen Reduction Reaction Catalysts

Abstract

Electrochemical methods are promising technical routes for future clean energy storage and conversion. Most of the electrochemical methods involve oxygen reactions. Unfavorable kinetics and sluggish reactions are the main challenges for these processes. We report here a facile synthesis of highly efficient oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts. The catalysts are synthesized through the fine-tuning of metal ions (M, specifically Co, Ni, Zn, and Cu) in Prussian blue analogues (PBAs) and thus termed as M-PBAs. The CoNi-PBA-2 catalyst shows the highest activity toward OER with an onset potential at 280 mV and a Tafel slope of 63 mV dec–1. Zn-PBA catalysts demonstrate high selectivity in two-electron-transfer ORR. The H2O2 yield is as high as 88% at 0 V vs RHE. Density functional theory (DFT) calculations also confirm the high selectivity of Zn-PBA toward H2O2 in ORR.

Amorphous Nickel Oxides Supported on Carbon Nanosheets as High-Performance Catalysts for Electrochemical Synthesis of Hydrogen Peroxide

“…The mass transport-corrected kinetic partial current density for H 2 O 2 production ( J k ), which is a common metric for 2e-ORR, , is shown in Figure c for our amorphous NiO x -C and the reported catalysts. ,,,− Obviously, the amorphous NiO x -C shows an outstanding performance. Considering the easy fabrication and excellent performance, the amorphous NiO x supported on carbon nanosheets can be a promising catalyst for H 2 O 2 production.…”

Crystal Engineering Enables Cobalt-Based Metal–Organic Frameworks as High-Performance Electrocatalysts for H2O2 Production

“…The PXRD patterns of the two particles are nearly the same with slight variation in relative intensity (Figure i). The peak intensity ratio of (110)/(002) for ZnCo-ZIF-R3 (5.65) is higher than that of ZnCo-ZIF-C3 (4.33), in accordance with the predominant exposure of {110} and {001} facets in ZnCo-ZIF-R3 and ZnCo-ZIF-C3, respectively …”

Concurrently Engineered Lewis Acid Sites and Coordination Sphere Vacancies in CoFe Prussian Blue Analogues for Boosted Bifunctional Oxygen Electrocatalysis

“…From the OER and ORR electrocatalytic analysis, it was depicted that the highest electrocatalytic performance was shown by an optimum doping concentration of 3 mole % Zn. This effect can be better understood from the mechanism of OER that can be divided into the four electron–proton transfer steps ,, .25em * + normalH 2 normalO → normalH normalO * + normalH + + normale − normalH normalO * → normalO * + normalH + + normale − normalO * + normalH 2 normalO → normalH normalO normalO * + normalH + + normale − normalH normalO normalO * → normalO 2 + normalH + + normale − where * refers to the active site of the catalyst. The mechanism for ORR in an alkaline medium is the same as above but in a reverse order.…”

“…From the OER and ORR electrocatalytic analysis, it was depicted that the highest electrocatalytic performance was shown by an optimum doping concentration of 3 mole % Zn. This effect can be better understood from the mechanism of OER that can be divided into the four electron−proton transfer steps 32,71,72…”

“…From the OER and ORR electrocatalytic analysis, it was depicted that the highest electrocatalytic performance was shown by an optimum doping concentration of 3 mole % Zn. This effect can be better understood from the mechanism of OER that can be divided into the four electron–proton transfer steps ,, where * refers to the active site of the catalyst. The mechanism for ORR in an alkaline medium is the same as above but in a reverse order.…”