skip to main content

Title: Origin of Thermal and Hyperthermal CO 2 from CO Oxidation on Pt Surfaces: The Role of Post-Transition-State Dynamics, Active Sites, and Chemisorbed CO 2
Award ID(s):
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
Angewandte Chemie International Edition
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    Two platinum precursors, Pt(CO) 2 Cl 2 and Pt(CO) 2 Br 2 , were designed for focused electron beam-induced deposition (FEBID) with the aim of producing platinum deposits of higher purity than those deposited from commercially available precursors. In this work, we present the first deposition experiments in a scanning electron microscope (SEM), wherein series of pillars were successfully grown from both precursors. The growth of the pillars was studied as a function of the electron dose and compared to deposits grown from the commercially available precursor MeCpPtMe 3 . The composition of the deposits was determined using energy-dispersive X-ray spectroscopy (EDX) and compared to the composition of deposits from MeCpPtMe 3 , as well as deposits made in an ultrahigh-vacuum (UHV) environment. A slight increase in metal content and a higher growth rate are achieved in the SEM for deposits from Pt(CO) 2 Cl 2 compared to MeCpPtMe 3 . However, deposits made from Pt(CO) 2 Br 2 show slightly less metal content and a lower growth rate compared to MeCpPtMe 3 . With both Pt(CO) 2 Cl 2 and Pt(CO) 2 Br 2 , a marked difference in composition was found between deposits made in the SEM and deposits made in UHV. In addition to Pt, the UHV deposits contained halogen species and little or no carbon, while the SEM deposits contained only small amounts of halogen species but high carbon content. Results from this study highlight the effect that deposition conditions can have on the composition of deposits created by FEBID. 
    more » « less
  2. Abstract

    As the majority of fossil fuel carbon dioxide (CO2) emissions originate from cities, the use of novel techniques to leverage available satellite observations of CO2and proxy species to constrain urban CO2is of great importance. In this study, we seek to empirically determine relationships between satellite observations of CO2and the proxy species nitrogen dioxide (NO2), applying these relationships to NO2fields to generate NO2‐derived CO2fields (NDCFs) from which CO2emissions can be estimated. We first establish this method using simulations of CO2and NO2for the cities of Buenos Aires, Melbourne, and Mexico City, finding that the method is viable throughout the year. For the same three cities, we next calculate empirical relationships (slopes) between co‐located observations of NO2from the Tropospheric Monitoring Instrument and Snapshot Area Mode observations of CO2from Orbiting Carbon Observatory‐3. Applying varying combinations of slopes to generate NDCFs, we evaluate methodological uncertainties for each slope application method and use a simple mass balance method to estimate CO2emissions from NDCFs. We demonstrate monthly urban CO2emissions estimates that are comparable to emissions inventory estimates. We additionally prove the utility of our method by demonstrating how large uncertainties at a grid cell level (equivalent to ∼1–3 ppm) can be reduced substantially when aggregating emissions estimates from NDCFs generated from all NO2swaths (about 1%–6%). Rather than rely on prior knowledge of emission ratios, our method circumvents such assumptions and provides a valuable observational constraint on urban CO2emissions.

    more » « less