Partial deligandation activated ZIF-67 for efficient electrocatalytic oxygen reduction reaction

Abstract

Removing the blocked molecular groups and fully exposing the intrinsic active sites of metal-organic frameworks (MOFs) could give full play to their advantages of multi-active sites and multi-channel mass transfer, which will benefit the electrocatalytic oxygen reduction reaction (ORR) in fuel cells. Here, the partial diligandation-activated ZIF-67 (named as ZIF-67–400) with excellent ORR performance was obtained by simple low-temperature pyrolysis. The ORR electrocatalytic activity exhibits a half-wave potential of 0.82 V and the stability of maintaining 96% activity after 10 h of operation, which is comparable to commercial Pt/C. Further research studies reveal that the morphology, special dodecahedron configuration, and crystal structure of ZIF-67-400 are maintained well during the pyrolysis, but some hydrocarbon groups in the ligands are eliminated, resulting in the active sites being exposed and coordinated with the intrinsic porosity, improving the catalytic performance. This work may provide an alternative path for activating the electrocatalytic performance of metal-organic frameworks by low-temperature annealing.

XRD and Spectroscopic Investigations of ZIF—Microchannel Glass Plates Composites

“…The Raman spectra of powder samples jn-01 and jn-04 are presented in Figure 4 a,b. In the Raman spectra, peaks are seen that match up with the peaks of the corresponding ZIFs, which is in good agreement with data from the literature [ 52 , 53 , 54 , 55 , 56 , 57 , 58 ]. As seen in Figure 4 a, sample jn-01 shows the vibrational band characteristics of ZIF-8 (ZIF-L) that have been previously published in various papers [ 52 , 56 ].…”

In Situ Pyrolysis of ZIF-67 to Construct Co2N0.67@ZIF-67 for Photocatalytic CO2 Cycloaddition Reaction

“…As shown in Figure a, ZIF-67 begins to decompose at about 445 °C. The temperature at which ZIF-67 exhibits maximum weight loss is 540 °C, which is consistent with the literature. , By carefully adjusting the calcination temperature just below the point of carbonization, localized dissociation occurs within the structure, resulting in the emergence of intriguing properties in ZIF-67 . Therefore, ZIF-67 was calcined at various target temperatures (350, 400, 450, and 500 °C) under a N 2 atmosphere for 2 h to prepare various samples.…”

“…31,32 By carefully adjusting the calcination temperature just below the point of carbonization, localized dissociation occurs within the structure, resulting in the emergence of intriguing properties in ZIF-67. 33 Therefore, ZIF-67 was calcined at various target temperatures (350, 400, 450, and 500 °C) under a N 2 atmosphere for 2 h to prepare various samples. Subsequently, XRD was conducted to elucidate the structure of the obtained materials (Figure S2).…”