Radiolytic Water Splitting Sensitized by Nanoscale Metal–Organic Frameworks

Abstract

High-energy radiation that is compatible with renewable energy sources enables direct H 2 production from water for fuels; however, the challenge is to convert it as efficiently as possible, and the existing strategies have limited success. Herein, we report the use of Zr/Hf-based nanoscale UiO-66 metal− organic frameworks as highly effective and stable radiation sensitizers for purified and natural water splitting under γ-ray irradiation. Scavenging and pulse radiolysis experiments with Monte Carlo simulations show that the combination of 3D arrays of ultrasmall metal-oxo clusters and high porosity affords unprecedented effective scattering between secondary electrons and confined water, generating increased precursors of solvated electrons and excited states of water, which are the main species responsible for H 2 production enhancement. The use of a small quantity (<80 mmol/L) of UiO-66-Hf-OH can achieve a γ-rays-to-hydrogen conversion efficiency exceeding 10% that significantly outperforms Zr-/Hf-oxide nanoparticles and the existing radiolytic H 2 promoters. Our work highlights the feasibility and merit of MOF-assisted radiolytic water splitting and promises a competitive method for creating a green H 2 economy.

A Multifunctional Covalent Organic Framework Nanozyme for Promoting Ferroptotic Radiotherapy against Esophageal Cancer

“…Highenergy radiation, including X-rays, may induce the production of ROS via the ionization and excitation of water and oxygen through a process known as radiolysis, 69 and Hf-based MOFs, such as UiO-66(Hf), have been shown to catalyze this process. 70 With due consideration given to the fact that TADI-COF has a stronger X-ray absorption capacity than UiO-66(Hf), the radiolytic effect exerted by TADI-COF on water under 6 MV X-ray radiation was investigated (Figure 3A). Specifically, exposure of TADI-COF (1.0 mg/mL), supplemented with dihydroethidium (DHE), to X-ray radiation (10 Gy) resulted in a significant enhancement of fluorescence at 620 nm due to the oxidation of DHE to ethidium ions by radiolytically generated •O 2 − ; 71 the resulting fluorescence intensity being 4.2 times greater than that of the radiated DHE solution (Figures 3B and S6).…”

“…High-energy radiation, including X-rays, may induce the production of ROS via the ionization and excitation of water and oxygen through a process known as radiolysis, and Hf-based MOFs, such as UiO-66­(Hf), have been shown to catalyze this process . With due consideration given to the fact that TADI-COF has a stronger X-ray absorption capacity than UiO-66­(Hf), the radiolytic effect exerted by TADI-COF on water under 6 MV X-ray radiation was investigated (Figure A).…”

Ambient γ‐Rays‐Mediated Noble‐Metal Deposition on Defect‐Rich Manganese Oxide for Glycerol‐Assisted H2 Evolution at Industrial‐Level Current Density

“…Commercial 60 Co γ-rays are a practical, versatile, scalable technique for synthesizing metal NPs. [13] γ-rays ionize and excite the water to produce abundant reactive species such as solvated electrons and H * radicals. [14] The transient reducing species can quickly reduce metal ions to the zero valent states and give rise to metal NPs in metal oxides.…”

Water Radiocatalysis for Selective Aqueous-Phase Methane Carboxylation with Carbon Dioxide into Acetic Acid at Room Temperature

“…In the mechanism, the reactive H 2 production was always observed (Figure S9 and Table S7). For pure water, H 2 is produced mainly by reactions of e aq − , •H, and water, 38 including the e aq − + H 2 O reaction to produce H 2 and OH − , the •H + e aq − + H 2 O reaction to produce H 2 and OH − , and the coupling of •H radicals to produce H 2 . The introduction of CH 4 to water significantly increased the H 2 production, probably because the trapping of •OH radicals by CH 4 stabilized e aq − to facilitate the H 2 production, whereas the introduction of CO 2 to water consumed e aq − so as to slightly decrease the H 2 production.…”