Substituted Ti(IV) in Ce-UiO-66-NH₂ Metal–Organic Frameworks Increases H₂ and O₂ Evolution under Visible Light

Abstract

Metal–organic frameworks (MOFs) as photocatalysts have received increasing attention. In this work, a dual metal-substituted UiO-66-NH2 (Ti/Ce-MOF) containing different Ti/Ce mole ratios (x = 0–2.46) has been prepared via post-synthetic exchange between Ce-UiO-66 and TiCl4, followed by amination. The solid had a high surface area (828–937 m2/g) and a large pore volume (0.451–0.507 m3/g). Under visible light, Ti/Ce-MOF showed x-dependent activity for H2O reduction and oxidation on a film electrode, respectively. However, such a change for H2 evolution in a Na2S/Na2SO3 aqueous solution was observed only after CdS loading. In combination with the photoluminescence and band parameters, we propose that the photoactivity of Ti/Ce-MOF for redox reaction is determined by its ability for electron transfer. Furthermore, there is an interfacial electron transfer from Ti/Ce-MOF to CdS and a hole transfer from CdS to Ti/Ce-MOF, respectively, significantly improving the efficiency of charge separation for redox reactions. This work offers a new insight that Ti substitution benefits the performance of Ce-based MOF.

Pristine and Postsynthetically Modified UiO-66-NH2 (Ce) MOF for Efficient Capture of Uranium from Aqueous Solutions

“…The as prepared and activated UiO-66-NH 2 (Ce) MOF was initially characterized by powder XRD (pXRD) to ensure purity and crystal structure. The pXRD pattern of the solid product (Figure a) revealed set of reflections which can be indexed to pure UiO-66-NH 2 (Ce) MOF as reported in literature. , Moreover, it is well-known fact that amine (−NH 2 ) group is an excellent functionality for anchoring different functional groups, leading to tailor-made MOF materials for targeted applications . Thus, it was perceived that modification of the tethered amine group by diphenylphosphinyl (Ph 2 PO−) group fixation to afford −NHPOPh 2 (phosphinic amide) functionality could enhance the uranium uptake capacity of the MOF, which is the primary aim of the present work.…”

Competitive CO2/H2O Adsorption on CALF-20

“…Recently, Ho and Paesani used molecular dynamics to explain the competitive behavior of H 2 O and CO 2 on CALF-20. 56 They showed that in the presence of CO 2 , water molecules form a more connected hydrogen-bonded network that decreases water entropy leading to a retardation in its capacity. Such a unique behavior where the presence of CO 2 retards H 2 O adsorption, to the best of our knowledge, has not been noticed before.…”

Ionothermal Synthesis and Photoactivity of Ti17 and Ti19‐Oxo Clusters Functionalized by Sulfate and 1,10‐Phenanthroline Ligands

“…[ 1‐14 ] TOCs are adorned with various functional ligands, including carboxylates, phosphonates, sulfates, azoles, calixarenes, hydroxyls, and more. [ 15‐27 ] These ligands play crucial roles in modulating the cluster structures and physicochemical characteristics, while also offering abundant applications in photocatalysis, semi conductivity, environmental remediation (such as dye degradation), and wastewater treatment. [ 28‐38 ] Moreover, recent advances in the decagram‐scale synthesis of TOCs for various applications show their commercial potential as future sustainable catalysts to be utilized at the industrial scale.…”