Room temperature design of Ce(iv)-MOFs: from photocatalytic HER and OER to overall water splitting under simulated sunlight irradiation

Abstract

The development of MOF-based efficient and reusable catalysts for hydrogen production under simulated sunlight irradiation, especially through overall water splitting, remains challenging. This is mainly due to either the inappropriate...

MOF-on-MOF Composites with UiO-66-Based Materials as Photocatalysts for the Overall Water Splitting under Sunlight Irradiation

“…Other factors, such as the saturation of the MOF porosity network by O 2 , which is more soluble than H 2 or the saturation of a deareated water solution with O 2 (more water soluble than H 2 ), can justify the observation of the measured H 2 to O 2 ratio. 53 Interestingly, UiO-66(Zr)-NH 2 @UiO-66(Ce) composites were more active compared to UiO-66(Zr)-NH 2 or UiO-66(Ce) solids for the OWS into H 2 and O 2 under both UV−vis and simulated sunlight irradiation. Among the various solids tested, UiO-66(Zr)-NH 2 -25@UiO-66(Ce) sample exhibited the highest activity of H 2 and O 2 production rate of 375 and 170 μmol g −1 in 22 h under simulated sunlight irradiation (Figure 6).…”

“…In this study, attempts to measure possible formation of H 2 O 2 by titration with titanyl oxalate, as previously reported do not reveal its formation during the photocatalytic OWS using UiO-66­(Zr)-NH 2 -25@UiO-66­(Ce). Other factors, such as the saturation of the MOF porosity network by O 2 , which is more soluble than H 2 or the saturation of a deareated water solution with O 2 (more water soluble than H 2 ), can justify the observation of the measured H 2 to O 2 ratio . Interestingly, UiO-66­(Zr)-NH 2 @UiO-66­(Ce) composites were more active compared to UiO-66­(Zr)-NH 2 or UiO-66­(Ce) solids for the OWS into H 2 and O 2 under both UV–vis and simulated sunlight irradiation.…”

“…The somewhat lower oxygen content observed compared to the H 2 O stoichiometry may be due to several reasons, including the partial consumption of the photogenerated holes by spurious electron donor impurities or the in situ reaction of O 2 evolved during the photocatalytic reaction . In fact, several previous studies of photocatalytic OWS using MOFs such as MIL-125­(Ti)-NH 2 , UiO-66­(Zr/Ce/Ti), UiO-66­(Ce)-NH 2 , MIL-173­(Zr/Ti), and IEF-11, among other precedents, have also reported a H 2 to O 2 molar ratio higher than the theoretical value of 2. These observations can be related to several factors with different contributions that include H 2 O oxidation to H 2 O 2 that later could be decomposed to O 2 .…”

Rapid synthesis of cerium-UiO-66 MOF nanoparticles for photocatalytic dye degradation

“…The precipitation of the Ce-UiO-66-X (X = NH 2 , OH, H, NO 2 , COOH) materials can be compared to other aqueous-based room temperature methods recently reported in literature which have been performed for periods between 15 min and few hours. 36 For example, Ce-UiO-66-NH 2 was synthesised in 2 hours at room temperature with yield of 42%, 37 which is lower than the yield of 58% by the method reported here. The synthesis of Ce-UiO-66-NH 2 by Zaremba et al in water and DMF with different modulators (acetic and formic acid) showed that using DMF required a time of synthesis from 30 to 15 min.…”

MOFs as Versatile Catalysts: Synthesis Strategies and Applications in Value-Added Compound Production

“…The highly crystalline Ce-UiO-66-NH 2 and Zr-UiO-66-NO 2 were fabricated as active photocatalysts for HER and OER. Also, Ce-UiO-66-NH 2 with supported Pt NPs demonstrated water splitting into H 2 and O 2 under simulated sunlight irradiation . Hematite@ZIF-67 core–shell p–n junction can improve the charge carrier transfer between ZIF-67 and hematite due to hematite as a catalyst with its high chemical stability for photoelectrochemical water splitting or water oxidation and enhanced surface oxygen evolution reaction (OER) kinetics .…”