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Atmospheric-pressure ammonia synthesis on AuRu catalysts enabled by plasmon-controlled hydrogenation and nitrogen-species desorption
The Haber–Bosch process for ammonia synthesis contributes up to ~3% of global greenhouse gas emissions. Plasmonic catalysts strongly concentrate light and can alter the reaction intermediates via out-of-equilibrium processes, providing the potential for an alternative, less-energy-intensive pathway to synthesize ammonia. Here, in this study, we show that gold-ruthenium (AuRu) bimetallic nanoparticles can synthesize ammonia at room temperature and pressure using visible light. We create AuRu alloys with varying compositions and achieve ammonia production rates of ~60 μmol per gram of catalyst bed per hour. In situ infrared spectroscopy reveals that light accelerates the hydrogenation of nitrogen intermediates compared to conventional thermal catalysis. Through computational modelling, we demonstrate that photo-excited electrons enable associative hydrogenation pathways for nitrogen activation rather than direct nitrogen–nitrogen bond breaking. This light-assisted mechanism requires both hydrogen and light working together to overcome the nitrogen activation barrier, mimicking how biological enzymes produce ammonia naturally and providing fundamental insights for developing sustainable, energy-efficient chemical synthesis.
Mitigated ammonium nitrate inhibition in SCR over Cu-SSZ-13 + Ce/Mn-oxide composite catalysts: insights from temperature-programmed desorption analysis
Ce/Mn-oxide reduces the quantity and stability of NH 4 NO 3 deposits in Cu-SSZ-13.
Accelerating strain phenotyping with desorption electrospray ionization-imaging mass spectrometry and untargeted analysis of intact microbial colonies
Significance Synthetic biology has entered an era in which reading and writing DNA sequences are no longer rate-limiting steps in microbial strain engineering. Indeed, analytical methods measuring the resulting metabolic outcomes of specific gene edits have lagged behind the ability to generate new recombinant strains. Herein, we report a mass spectrometry strategy to accelerate these analytical workflows by directly analyzing metabolites and molecules produced from engineered microorganisms in a multiplexed process. Using untargeted acquisitions and unsupervised analytics, we assess the molecular features that change across discrete strains including primary target species, secondary products, and species outside the engineered fatty acid biosynthesis pathway.
Desorption and Co–Dissolution of Uranium–Bearing Solids During Alkalinity–Enhanced Flushing of Contaminated Sediments
Elevated uranium concentrations in groundwater remain a persistent challenge at contaminated sites. Several sites rely on natural flushing of uranium as a remediation strategy. Uncertainties in conceptual models can cause remediation strategies to underestimate timeframes required to reach remediation goals. In this study, laboratory experiments were conducted to investigate uranium flushing of sediments from a site with persistent groundwater contamination. Six columns were used to simulate alkalinity-enhanced flushing of uranium from sediments, by switching influent alkalinity after ~12 pore volumes. About 20% to 31% of sediment uranium was consistently flushed from the sediments. K d values varied greatly (5.3 to 117 L/kg) but were consistently lower (20% to 50%) during influents with elevated alkalinity. The mass of uranium recovered from the columns also was consistently higher (5% to 80%) during alkalinity-enhanced flushing periods. However, column experiments with sequentially increasing alkalinity showed diminishing returns in uranium elution at higher carbonate concentrations. The loss of flushing efficiency is attributed to significant calcite precipitation at higher alkalinities. Furthermore, the results show that alkalinity-enhanced flushing of uranium could be employed as a viable remediation scheme if calcite precipitation could be minimized in a field application.
Ab initio Molecular Dynamics Simulations of Rare Earth (III) Ion Desorption from Silica Surfaces.
Abstract not provided.
Matrix-assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry for Advanced Polymer Charaterization
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Parylene-N Coatings of Thin Foils for the Mitigation of Neutral Contaminant Desorption and Plasma Formation
Previous experiments utilizing the planar MITL foil platform (T.J. Smith et al. RSI 2021) on the 1-MA, 100-ns Mykonos facility have shown neutral atomic and molecular hydrogen in the gap after rapid heating of the foil surfaces before breakdown. Additionally, previous attempts at using parylene-N as a coating for power flow surfaces on the 1-MA, 100-ns Zebra facility have shown tamping of the electrothermal instability at thicknesses of 50-60 μm (T.M. Hutchinson et al. Phys. Rev. E 2018).
Towards Portable Laser Desorption Postionization Mass Spectrometry Utilizing Microchip Laser Pulses
A 355 nm, 1.5 ns, up to 1 kHz microchip laser system has been tested to both yield ablation spots and postionize material within a plasma plume. A 30 µJ pulse energy microchip laser successfully ablated all samples: 6601 aluminum, 316 and 304 stainless steel, and Mo metal. While visible ablation craters were observed on all samples mentioned above, the stainless-steel samples displayed visible color changes in the resolidified iron, indicating ionization with the 355 nm pulses during ablation. Additionally, when used to intercept a plasma plume of Cs 2 CO 3 made with a separate laser system, the microchip laser pulses yielded Cs + emission signal otherwise not observed. With these experiments completed, the microchip laser has been successfully verified for readiness to be integrated into the front end of a mass spectrometer system as the ion source.
Demonstration Test Report: Vacuum Thermal Desorption (VTD) Testing to Support West Area Waste Feed Test 2
Approximately 54 million gallons of radioactive and hazardous waste are stored in underground storage tanks at the U.S. Department of Energy’s (DOE’s) Hanford Site in southeastern Washington State. The Hanford Waste Treatment and Immobilization Plant (WTP) is being constructed to immobilize the waste in glass waste forms. The baseline configuration of the WTP includes a Pretreatment Facility to separate the wastes into a small volume of high-level waste (HLW) containing most of the radioactivity and a larger volume of low-activity waste (LAW) containing most of the non-radioactive chemicals. The HLW will be converted to glass in the HLW vitrification facility for ultimate disposal at a federal repository.
Indirect solution analysis - Desorption electrospray Ionization
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Advancing Indirect Solution Analysis with Desorption Electrospray Ionization for Rapid Contaminant Analysis
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Adsorbent Facilitated, Rapid Environmental Mass Spectrometric Sampling; ISA-DESI: Indirect Solution Analysis-Desorption Electrospray Ionization
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Measuring the Interfacial Chemistry of Micro- and Nano-Plastics Using Matrix Assisted Laser Desorption Ionization Mass Spectrometry (MALDI)
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Advancing Detection of Per- and Polyfluoroalkyl Substances via Indirect Solution Analysis with Desorption Electrospray Ionization
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