Reduction of soluble hexavalent uranium (U(VI)) to sparingly soluble tetravalent uranium (U(IV)) with semiconductor photocatalysts is recognized as a novel, green, and simple U‐extraction method. Furthermore, effective charge separation and utilization are critical factors to achieve high‐efficiency U(VI) photoreduction. Herein, a UiO‐66‐based heterostructured photocatalyst (MnOx/UiO‐66/Ti3C2Tx) with spatially separated dual cocatalysts (MnOx nanoparticles and Ti3C2Tx MXene nanosheets) is successfully developed for efficient U(VI) photoreduction without sacrificial agents. As co‐catalysts, MnOx nanoparticles favor the trapping of holes, while Ti3C2Tx MXene nanosheets tend to collect electrons. Consequently, the photogenerated holes and electrons flow into and out of the photocatalyst, respectively, achieving efficient charge separation required by MnOx/UiO‐66/Ti3C2Tx to remove U(VI). Impressively, the U(VI) removal ratio via MnOx/UiO‐66/Ti3C2Tx reaches to 98.4% in the U(VI) solution after 60 min, with a photoreaction rate constant of 0.0948 min−1. Moreover, MnOx/UiO‐66/Ti3C2Tx exhibits brilliant U(VI) extraction capacity in various U(VI) wastewater and U(VI)‐spiked real seawater. Further mechanistic studies indicates that the photogenerated electrons are transferred from the conduction band of UiO‐66 to Ti3C2Tx MXene to reduce U(VI) and generate ·O2–, further leading to a stable crystal phase of (UO2)O2·2H2O. Furthermore, the photogenerated holes are extracted by MnOx nanoparticles in MnOx/UiO‐66/Ti3C2Tx to oxidize water.
The
unsatisfactory performance of dehydrogenation catalysts has
been the bottleneck for liquid organic hydrogen carrier (LOHC) development.
After systematic experiments, the Au/Pd core/shell catalysts were
screened from a series of Pd–M (M = Au, Ag, Ru, Rh) combinations
for dehydrogenation of dodecahydro-N-ethylcarbazole
(12H-NEC) through a one-pot wet chemical synthesis. The ratio of Pd
to Au is also within the scope of the experiment, and it was found
that the catalytic activity was following the order of Au1Pd1.3 > Au1Pd2 > Au1Pd1 > Ru1Pd1.3 > Au1Pd0.7 > Rh1Pd1.3 > Ag1Pd1.3 supported on rGO for the dehydrogenation
process. Au1Pd1.3/rGO greatly improves the efficiency
of the dehydrogenation
reaction, specifically; while maintaining selectivity and conversion
rate of 100%, the reaction time was shortened by 43% compared to the
monometallic Pd/rGO catalyst with the highest activity we prepared
before, and compared to the best performing bimetallic catalyst in
the literature, the optimal reaction time in this work was reduced
by 71% when the hydrogen storage requirements of the US DOE (Department
of Energy) are met. A cycle performance experiment was performed to
verify its excellent catalytic stability. Further catalyst characterization
also proves that it has good morphology and stability. A kinetics
calculation was carried out to obtain fundamental reaction parameters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.