RESEARCH

Mauricio C. Diaz and Perla B. Balbuena, “On the Role of Surface Oxygen during Nascent Single-Walled Carbon Nanotube Cap Spreading and Tube Nucleation on Iron Catalysts,” Carbon, 184, 470-478 (2021).

Single-walled carbon nanotubes (SWCNTs) are commonly grown in oxygen-rich environments. The precursor used as input for the SWCNT synthesis reaction typically provides oxygen atoms either as a pure gas or as an oxygen-containing compound. Similarly, metal oxide substrates are used to support the catalysts or as reactor wall materials and can transfer oxygen atoms while in contact with the catalytic particles… View more 

Hsin-Yun Chao, Hua Jiang, Francisco Ospina Acevedo, Perla B. Balbuena, Esko I. Kauppinen, John Cumings, and Renu Sharma, “Structure and Activity Relationship for Single-Walled Carbon Nanotube Growth Confirmed by In-Situ observations and Modeling,” Nanoscale, 12, 21923-21931 (2020).

The structure and phase transformation of a cobalt (Co) catalyst, during single walled carbon nanotube (SWCNT) growth, is elucidated for inactive, active and deactivated nanoparticles by in situ imaging using an environmental transmission electron microscope. During nanotube growth, the structure was analyzed using Miller indices to determine the types of planes that favor anchoring or liftoff of nanotubes from the Co catalyst… View more

Mauricio C. Diaz, Hua Jiang, Esko Kauppinen, Renu Sharma and Perla B. Balbuena, “Can single-walled carbon nanotube diameter be defined by catalyst particle diameter?,” J. Phys. Chem. C, 123, 30305-30317, (2019).

The need of designing and controlling single-walled carbon nanotube (SWCNT) properties is a challenge in a growing nanomaterials-related industry. Recently, great progress has been made experimentally to selectively control SWCNT diameter and chirality. However, there is not yet a complete understanding of the synthesis process, and there is a lack of mathematical models that explain nucleation and diameter selectivity of… View more 

Behnaz Rahmani Didar and Perla B. Balbuena, “Methane Dehydrogenation on Cu and Ni Surfaces with Low and Moderate Oxygen Coverage,” Int. J. Quantum Chemistry, 2019; e26065.

First-principles density functional theory calculations are carried out to evaluate energy barriers and mechanisms for the dehydrogenation reactions of CH4 on clean and oxygen-covered surfaces of Cu (111) and Ni (111) with low and moderate oxygen coverage. In the presence of oxygen, two possible pathways have been evaluated. The more likely pathway, which is further analyzed, is that CH4 loses an H to the surface O… View more 

Behnaz Rahmani Didar and Perla B. Balbuena, “Reactivity of Cu and Co Nanoparticles Supported on Mo-doped MgO,” Ind.& Eng. Chem. Res., 58, 18213-18222, (2019).

First-principles density functional theory calculations are used to study the presence of Mo in the MgO support and its effect on the adsorption of Cu and Co nanocatalyst particles, as well as the mechanisms of C2H2 adsorption onto those nanoparticles. Furthermore, the initial steps of C2H2 dissociation on MgO-supported Cu and Co catalyst nanoparticles are investigated. Calculated formation energies suggest that the most likely locations of Mo-dopant atoms are on the top layer of the MgO support and under the overlying catalyst nanoparticles… View more