2 research outputs found
Unraveling Dimensional Tuning: From 2D to 3D in Covalent Organic Frameworks for Enhanced 2e– Oxygen Reduction Reaction
No full textCovalent organic frameworks (COFs) with a two-dimensional (2D) topology have recently emerged as promising catalyst systems for the electrosynthesis of hydrogen peroxide (H2O2) from oxygen (O2). However, designing 2D catalysts to achieve higher H2O2 selectivity presents a significant challenge because of the extensive layer stacking and the aggregated active sites located in the basal planes. It results in lower atom utilization, which requires attention. In this study, we present two functionally similar COFs: one with a 2D rhombus topology (2D@BT_TPA-COF) and another with a three-dimensional (3D) noninterpenetrated pts topology (3D@BT_TPA-COF). Both COFs were utilized for the 2e– oxygen reduction reaction (2e– ORR). Tunning the dimensionality from 2D to 3D resulted in an increase in H2O2 selectivity from approximately ∼56% to approximately ∼96% (at 0.4 V) and a rise in the turnover frequency (TOF) from 0.05 to 0.08 s–1 at 0.3 V. Nonaggregated active site distribution over 3D topology, featuring higher active site exposure, provides better access to the O2/electrolyte and facilitates electron transfer leading to higher 2e– ORR activity and selectivity compared to the 2D counterpart
Water Reclamation from Synthetic Urine Using Tandem Proteus mirabilis and Pt-Ni/Boron-Doped Diamond Electrodes
No full textAbayomi Omoogun, University of Texas - El Paso, United StatesGalilea De La O, University of Texas - El Paso, United StatesRuma Paul, University of Texas - El Paso, United StatesAngelica A. Chacon, University of Texas - El Paso, United StatesSuzatra Chatterjee, University of Texas - El Paso, United StatesNicole I. Jones, University of Texas - El Paso, United StatesJennifer Apodaca, University of Texas - El Paso, United StatesCarlos R. Cabrera, University of Texas - El Paso, United StatesICES303: Physico-Chemical Life Support- Water Recovery &
Management Systems- Technology and Process DevelopmentThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.This study introduces a bioelectrochemical system (BES) for
water reclamation from synthetic urine, addressing the
critical need for efficient wastewater recycling in
long-duration space missions. The system integrates the
ureolytic bacterium Proteus mirabilis with a
platinum-nickel-modified boron-doped diamond electrode
(Pt-Ni/BDDE) to convert urea, a major component of
synthetic urine, into ammonia, which is then
electrochemically oxidized to nitrogen gas. Proteus
mirabilis was immobilized on the Pt-Ni/BDDE under various
applied potentials (open circuit, –0.1 V, –0.2 V, and –0.3
V vs. Ag/AgCl (4 M KCl)) to investigate the effect of mild
cathodic bias on bacteria adhesion, viability, and biofilm
formation. The results indicate that increasingly negative
potential promotes stronger bacteria attachment and
enhanced ureolytic activity. When exposed to synthetic
urine containing 0.1 M urea at 8.00 pH, the bacteria
catalyze urea hydrolysis via urease, producing ammonia and
carbon dioxide. The ammonia is subsequently oxidized at the
electrode surface, monitored using cyclic voltammetry from
0.2 V to 0.8 V vs. Ag/AgCl (4M KCl) at a scan rate of 1
mV/s. Results show that higher bacteria immobilization
potential improve both bacteria adhesion and ammonia yield,
as evidenced by increased ammonia oxidation reaction (AOR)
peak current densities. This approach offers dual benefits:
it facilitates urea removal to reduce water loss and
harnesses energy from ammonia oxidation, contributing to a
more efficient and self-sustaining Environmental Control
and Life Support System (ECLSS). This research provides a
foundation for biologically integrated water treatment
technologies suited for space habitats and potentially for
wastewater systems on earth
