03/31/2022
By Sokny Long

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a doctoral dissertation defense by Jie Hu on “Non-thermal Plasma Assisted Pd Catalyst Deactivation in Electrochemical CO2 Reduction Reaction.”

Ph.D. Candidate: Jie Hu
Defense Date: Tuesday, April 12, 2022
Time: 11 a.m. to 1 p.m. EST
Location: This will be a virtual defense via Zoom. Those interested in attending should contact jie_hu@student.uml.edu and committee advisor, Fuqiang_liu@uml.edu, at least 24 hours prior to the defense to request access to the meeting.

Committee Chair (Advisor): Fuqiang Liu, Associate Professor, Department of Mechanical Engineering

Committee Members:

  • Xinfang Jin, Assistant professor, Department of Mechanical Engineering, UMass Lowell
  • Ertan Agar, Assistant professor, Department of Mechanical Engineering, UMass Lowell
  • KwokFan Chow, Associate professor, Department of Chemistry, UMass Lowell

Brief Abstract:

Electrochemical CO2 reduction reaction (CO2RR) through renewable electricity is deemed as one of the promising processes to convert this notorious green-house gas to useful products. In CO2RR, Pd based catalysts are commonly used due to their high product selectivity toward formic acid or formate. Formate has a high market value per energy (cents/kWh), making it a candidate of particular interest. However, efficient conversion of CO2 to formate is typically plagued by rapid catalyst deactivation due to strong adsorption of CO as an inevitable minor product. In this Ph.D. dissertation, non-thermal plasma was employed to assist electrochemical CO2RR. Particularly, the reactive oxidative species generated by a non-thermal plasma jet ignited above the electrolyte in an electrochemical system are hypothesized to be able oxidize and remove the adsorbed CO on the catalyst. To verify the hypothesis, we conducted studies and analysis of electrochemical CO2 reduction reaction using Pd catalysts in the presence of a low-temperature non-thermal plasma jet. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) studies showed greatly improved CO2RR activity, and the enhanced activity was found to directly correlate to the enlarged hydrogen desorption peak in the presence of plasma discharge. The formate yields of electrochemical CO2RR detected by NMR suggested a great enhancement in the presence of plasma discharge. To elucidate the improved performance in CO2RR, multi-component physics-based simulation was conducted to study species transport and physicochemical kinetics at the plasma-electrolyte interface. Simulation results reveal that instead of solvated electrons, hydroxyl radicals and other short-lived species, the generated H2O2 is long-lived and is responsible for deactivation of Pd catalysts in electrochemical CO2RR. The oxidizing environment due to the presence of H2O2 generated by plasma could prevent the Pd surface from being poisoned by CO. Further electrochemical studies showed that H2O2 electroreduction may alter hydrogen sorption and desorption of on Pd, possibly creating the active PdHx phase for effective CO2RR. Future work will extend this discovery and investigate non-thermal plasma assisted electrochemical conversion of other systems.

All interested students and faculty members are invited to attend the online defense via remote access.