Engineering topics

Oddo, Alexander M

Publications and source records attributed to Oddo, Alexander M.

3 records

DOE OSTI2025

Multistep catalytic abiotic CO2 conversion to sugars through C1 intermediates

Carbon dioxide (CO2) to multicarbon (Cn) upgrading for commodity chemicals, fuel production, or artificial food synthesis using renewable energy input is a golden target for researchers in sustainable carbon emission reduction. Here, we explore and analyze a flexible modular roadmap for the task, utilizing sequential electro-, photo-, and organocatalysis to develop a strategy for CO2 conversion using the key and elusive formaldehyde precursor of interest for sugar generation. We study the electrochemical carbon dioxide reduction reaction to methanol in a flow cell and its discontinuous photooxidation to formaldehyde (PMOR) with excellent selectivity. Utilizing a highly active N-heterocyclic carbene catalyst enables tunable generation of C4-C6 aldoses without undesirable byproducts, with carbon conversion yield reaching 60 to 80% for desired pentose, tetrose, and triose product mixtures and over 20% for hexose. This approach presents a roadmap for CO2 valorization, aiming to bridge carbon waste streams with sustainable sugar synthesis and opening broad avenues for green chemical production.

CO2 valorization↗

DOE OSTI2025

Exploring the Structural Origins of Optically Efficient One-Dimensional Lead Halide Perovskite Nanostructures

Metal halide perovskites have excellent optoelectronic properties. This study aims to determine how the optoelectronic properties of a model perovskite, cesium lead bromide (CsPbBr3), change with length and thickness in one dimension (1D). By examining the photophysics of CsPbBr3 quantum dots (QDs), nanowires (NWs), and nanorods (NRs), we observe the influence of confinement, exciton diffusion, and trapping on their optical properties. Our findings reveal that exciton diffusion to trap states limits the photoluminescence quantum yield (PLQY) of 1D CsPbBr3 in the weakly confined regime (8-14 nm) and explains their long-lived exciton dynamics, while enhanced radiative rates contribute to achieving near-unity PLQY in the strongly confined regime (<7 nm). Consequently, blue-emitting, 2.4 nm-thick CsPbBr3 NRs were 3.6X more emissive than the conventional CsPbBr3 QDs. This study underscores how structural optimization can improve the optoelectronic performance of CsPbBr3 and provides insight into the complex interplay of radiative and nonradiative processes in 1D ionic semiconductors.

Oddo, Alexander M↗

DOE OSTI2025

Photocatalytic Methanol Dehydrogenation with Switchable Selectivity

Switchable selectivity achieved by altering reaction conditions within the same photocatalytic system offers great advantages for sustainable chemical transformations and renewable energy conversion. In this study, we investigate an efficient photocatalytic methanol dehydrogenation with controlled selectivity by varying the concentration of nickel cocatalyst, using zinc indium sulfide nanocrystals as a semiconductor photocatalyst, which enables the production of either formaldehyde or ethylene glycol with high selectivity. Control experiments revealed that formaldehyde is initially generated and can either serve as a terminal product or intermediate in producing ethylene glycol, depending on the nickel concentration in the solution. Mechanistic studies suggest a unique role of ionic nickel as an additional photoelectron competitor that can significantly influence selectivity, alongside its well-established function as a hydrogen evolution reaction cocatalyst under photocatalytic conditions. The demonstrated switchable selectivity provides a new tool for producing diverse products from methanol, while advancing the understanding of cocatalyst behavior for versatile catalytic performance.

Luo, Jie↗