Plasmon-enhanced electrocatalysis over Cu-based bimetallic tandem catalysts

Zhu, Li (2025): Plasmon-enhanced electrocatalysis over Cu-based bimetallic tandem catalysts. Dissertation, LMU München: Fakultät für Physik

Abstract

The carbon dioxide electroreduction reaction (CO₂RR) and hydrogen evolution reaction (HER) are recognized as promising pathways toward a carbon-neutral energy cycle by enabling renewable electricity-driven carbon recycling and green hydrogen (H₂) production. However, the practical implementation of these technologies remains limited by intrinsic kinetic barriers and insufficient control over interfacial reaction pathways. CO₂RR suffers from the high CO₂ activation barrier and inefficient protonation and coupling of key intermediates *CO (an adsorbed carbon monoxide on the catalyst surface), while alkaline HER is hindered by sluggish water dissociation kinetics at the Volmer step. To address these challenges, this thesis explores plasmon-enhanced electrocatalysis as an advanced strategy to modulate interfacial electronic structure and reaction energetics through localized surface plasmon resonance (LSPR). Benefiting from its unique catalytic function and plasmonic response in the visible light region, copper (Cu) serves as a versatile platform for constructing Cu-based bimetallic tandem catalysts toward both CO₂ conversion and H₂ production. This thesis first elucidates the governing mechanisms of plasmon-enhanced electrocatalysis, including electromagnetic near-field enhancement, hot carriers generation and transfer, and localized photothermal heating, as well as their synergistic roles in accelerating reaction rate, stabilizing reaction intermediates, and steering product selectivity. Based on these principles, three representative Cu-based bimetallic systems, CuPd, CuNi and CuAg, were rationally designed and comprehensively investigated through experimental and theoretical studies. For CO₂RR, a CuPd tandem catalyst was developed by seed growth method. Under resonant illumination, plasmon excitation accelerates *CO formation on CuPd interfacial sites, which subsequently diffuse to Cu sites for coupling, thereby significantly improving the yield of C₂H₄ by 27%. For alkaline HER, a CuNi catalyst was constructed via pulsed electrodeposition to achieve strong interfacial coupling. Hot electrons generated on Cu are rapidly injected into Ni active sites, enhancing water dissociation, while the photothermal heating facilitates mass transport. Remarkably, the illuminated CuNi catalyst delivers performance surpassing commercial Pt. For the CuAg system, Ag nanoneedles serve as highly active *CO formation centers and catalyze *CO protonation toward methane. The balance of the ratio of Ag and Cu sites is highlighted as a key determinant of tandem catalytic selectivity toward hydrocarbon products, with potential of additional enhancement from plasmon excitation. Overall, this work establishes a unified plasmon engineering approach for Cu-based tandem electrocatalysts that enables efficient CO₂ conversion and green H₂ production. By revealing how plasmon excitation dynamically modulates charge transfer and reaction kinetics at complex bimetallic systems, this thesis provides valuable design principles for next-generation plasmon-enhanced electrocatalysts and supports the future integration of optical excitation into scalable electrochemical energy systems.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: Plasmon, electrocatalysis, CO2RR, HER, Cu-based catalysts
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 530 Physik
• Fakultäten: Fakultät für Physik
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 11. Dezember 2025
• 1. Bericht­erstatter:in: Cortes, Emiliano