Electrochemical nitrate reduction to ammonia on cu based nanoparticles using quantum mechanical simulations

Author

Kathan Bhavin Shukla, New Jersey Institute of TechnologyFollow

Document Type

Thesis

Date of Award

5-31-2024

Degree Name

Master of Science in Chemical Engineering - (M.S.)

Department

Chemical and Materials Engineering

First Advisor

Joshua Young

Second Advisor

Xianqin Wang

Third Advisor

Wen Zhang

Abstract

Nitrate reduction to ammonia (NRA) is critical for environmental remediation and energy conservation, as it can remove harmful nitrate (NO₃^-) from water sources while producing usable ammonia (NH₃). Cu represents one of the most promising non-noble-metal NRA electrocatalysts. However, the intrinsic catalytic activity of Cu facets and their influence under different pH conditions remain unclear, particularly in the presence of ions commonly found in wastewater such as Cl^-, Na⁺, Mg²⁺, and Ca²⁺. Using density functional theory (DFT) calculations, we evaluated the nitrate reduction to ammonia (NRA) pathways on Cu(111), Cu(100), and Cu(110) surfaces across varying pH levels and contaminating ions. Our systematic thermodynamic and kinetic analysis revealed that proceeding through an *NOH intermediate is the most probable across all pH ranges. We observed that both the catalytic deoxygenation and hydrogenation processes in NRA are substantially affected by pH, and the presence of ions with pH- and ion-dependent rate-determining steps. Furthermore, we found that the presence of ions, especially Cl ions, enhances NO₃^- adsorption on all Cu facets. However, it influences the rate determining steps as well on each surface, with some steps, such as *NO to *NOH hydrogenation, becoming increasingly unfavorable.

Finally, we investigated NRA pathways on Cu-decorated Mxene surfaces to understand the effect of scaling Cu down to the atomic level. Cu functionalization of Ti₂CO₂ Mxene-led to a significant increase in the NRA catalytic activity. These findings offer new strategies for the rational design of MXene-based NRA electrocatalysts with significance in environmental and energy-related applications.

Recommended Citation

Shukla, Kathan Bhavin, "Electrochemical nitrate reduction to ammonia on cu based nanoparticles using quantum mechanical simulations" (2024). Theses. 2591.
https://digitalcommons.njit.edu/theses/2591