The present study proposes a new approach for direct CO2 conversion using primary radicals from water irradiation. In order to ensure reduction of CO2 into CO2 -• by all the hydrated electrons, we use formate ions to scavenge simultaneously the parent oxidizing radicals H • and OH • producing the same transient CO2 -• radicals. Conditions are optimized to obtain the highest conversion yield of CO2. The goal is achieved under mild conditions of room temperature, neutral pH and 1 atm of CO2 pressure. All the available radicals are exploited for selectively converting CO2 into oxalate that is accompanied by H2 evolution. The mechanism presented accounts for the results and also sheds light on the data in the literature. The radiolytic approach is a mild and scalable route of direct CO2 capture at the source in industry and the products, oxalate salt and H2, can be easily separated.

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.

The efficient use of renewable X/γ-rays or accelerated electrons for chemical transformation of CO2 and water to fuels holds promise for a carbon-neutral economy; however, such processes are challenging to implement and require the assistance of catalysts capable of sensitizing secondary electron scattering and providing active metal sites to bind intermediates. Here we show atomic Cu-Ni dual-metal sites embedded in a metal-organic framework enable efficient and selective CH3OH production (~98%) over multiple irradiated cycles. The usage of practical electron-beam irradiation (200 keV; 40 kGy min−1) with a cost-effective hydroxyl radical scavenger promotes CH3OH production rate to 0.27 mmol g−1 min−1. Moreover, time-resolved experiments with calculations reveal the direct generation of CO2•‒ radical anions via aqueous electrons attachment occurred on nanosecond timescale, and cascade hydrogenation steps. Our study highlights a radiolytic route to produce CH3OH with CO2 feedstock and introduces a desirable atomic structure to improve performance.

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A water stable tetrazolate‐containing metal‐organic framework, [Cd2(L)(OH)(H2O)2]n (1) [H3L = 5‐(4‐(tetrazol‐5‐yl)phenyl)isophthalic acid], was synthesized under solvothermal conditions and structurally characterized. Compound 1 displays a three dimensional porous network with one dimensional tubular channels based on trinuclear cluster [Cd3(μ3‐OH)N4C] units. Notably, 1 exhibits highly sensitive response to Cu2+ and Cr2O72– through luminescence quenching effects with the detection limit of 0.666 ppm for Cu2+ and 0.846 ppm for Cr2O72–, respectively. The possible mechanism of the luminescence quenching was discussed in detail.

The efficient use of renewable high-energy radiation (X/γ-rays or accelerated e‒) as the energy input for the chemical transformation of carbon dioxide (CO2) and water to energy-rich fuels holds new promise for a carbon-neutral, sustainable energy economy; however, such processes are challenging to implement, and require the assistance of catalysts capable of sensitizing the secondary electron scattering and providing active metal sites to bind intermediates. Herein, we report that atomic Cu-Ni dual-metal-sites embedded in a metal-organic framework matrix enable efficient and selective (~ 98%) conversion of CO2 to CH3OH in irradiated aqueous solutions. The reaction is initiated by the direct generation of CO2•‒ radicals via aqueous electrons attachment, followed by a series of interfacial reactions. We showed that the UiO-66(Hf) matrix serves as a radiation sensitizer to break electron yield limitation in water radiolysis, dramatically promoting CO2 activation and conversion efficiency. With the synergistic metal centers and a hydroxyl radical scavenger, we achieved stable and selective CH3OH production over multiple irradiation cycles. Pulse radiolysis experiments with theoretical calculations revealed the transient kinetics occurred on the nanosecond timescale and cascade hydrogenation steps. Our study highlighted an unprecedented catalytic route to produce CH3OH with CO2 feedstock and introduced a desirable atomic structure to improve performance.