Selective synthesis of ZIFs from zinc and nickel nitrate solution for photocatalytic H2O2 production

Zinc-ion hybrid supercapacitor-batteries with a leaf-like ZIF-L/MgNiO2 micro-sphere composite and a Zn2+/sulfonated poly(ether ether ketone) gel

“…33,38 ZIF-L shows a cluster of peaks with the principal ones at 2q = 10.80°, 12.50°, 14.90°, 16.45°, 17.90°and 20.00°corresponding to the (200), ( 211), ( 220), (310), ( 222) and (114) planes of the orthorhombic crystal structure of ZIF-L. The pattern and the assignments match well with reported XRD patterns of ZIF-L. [39][40][41][42] The ZIF-L structure (shown in Fig. 2) affords multiple sites via the nitrogens and the Zn 2+ nodes and they serve as the binding sites for electrolyte ions during charge-discharge.…”

“…ZIF-L is bridged by N–H⋯N hydrogen bonds which impart stability to the 2D-layered networked structure. 40 The ZIF-L morphology consists of several oriented facets. These planes drag through an array of Zn and O atoms, resulting in increased exposure of the MOF on the surface, thus imparting a very high effective surface area to ZIF-L. TEM images shown in Fig.…”

Determining Optical Band Gaps of MOFs

“…In general, literature reports employ Tauc analysis to analyze the optical absorption spectra of MOFs, giving rise to optical gaps that vary by more than 1 eV, likely because of discrepancies between linear fits. For example, reported “band gaps” (used interchangeably with optical gap) of ZIF-8 (Zn-(imidazolate) 2 ) vary between 3.87 and 5.45 eV, − UiO-66 (Zr 6 O 4 (OH) 4 (terephthalate) 12 ) vary between 2.50 and 4.07 eV, − and MIL-125 (Ti 8 O 8 (OH) 4 (terephthalate) 6 ) range from 3.1 to 4.62 eV. − Furthermore, calculated electronic band structures indicate most MOFs possess localized bonding, with discrete, nonoverlapping states . Given their molecular, rather than band-type, nature as well as the empirical observation that experimental spectra bear well-resolved peaks, suggests that MOFs should be well-suited to Gaussian peak-fitting, not Tauc analysis , to obtain optical gaps.…”

Recent progress in the design of photocatalytic H2O2 synthesis system

“…Therefore, various modification strategies have been devised, such as double substrate metal-organic framework, metal nanoparticles and MOF composite, etc ( Wang Z. et al, 2020 ; Duan et al, 2020 ; Younis et al, 2020 ; Fang et al, 2021 ). The results showed that the activity of H 2 O 2 synthesis was improved by modification of ZIF ( Chang et al, 2020 ) and MIL ( Isaka et al, 2019 ) type metal-organic framework materials. It was mainly attributed to the wider bandgap energy.…”