Details

Autor(en) / Beteiligte

• Wang, Vincent C.-C

Titel

Beyond the Active Site: Mechanistic Investigations of the Role of the Secondary Coordination Sphere and Beyond in Multi-electron Electrocatalytic Reactions

Ist Teil von

• ACS catalysis, 2021-07, Vol.11 (13), p.8292-8303

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The development of an electrocatalyst with a rapid turnover frequency, low overpotential, and long-term stability is highly desired for fuel-forming reactions, such as water splitting and CO2 reduction. The findings of the scaling relationships between the catalytic rate and thermodynamic parameters (i.e., free energy relationship) over a wide range of electrocatalysts provide useful guidelines and predictions for designing better catalysts for those redox reactions. However, such relationships also suggest that a catalyst with a high catalytic rate is typically associated with a high overpotential for a given reaction in the molecular system. Inspired by enzymes, the introduction of additional interactions through the secondary coordination sphere (SCS) beyond the active site, such as hydrogen-bonding or electrostatic interactions, has been shown to offer a promising avenue to disrupt these unfavorable relationships. Herein, the influence of these cooperative interactions on the faster chemical steps is further investigated, in addition to the rate-limiting step widely examined before, for molecular electrocatalysts with the structural and electronic modifications designed to facilitate the dioxygen reduction reaction, CO2 reduction reaction, and hydrogen evolving reaction. Based on the electrocatalytic kinetic analysis, the rate constants for faster chemical steps and their correlation with the corresponding thermodynamic parameters are evaluated. The results suggest that the effects of the SCS and beyond on these fuel-forming reactions are not necessarily beneficial for promoting all chemical steps and no apparent relation between rate constants and thermodynamic parameters is found in some cases studied here, which may implicate the design of electrocatalysts in the future. Finally, these analyses demonstrate that the characteristic features for voltammograms and foot-of-the-wave-analysis plots are associated with the specific kinetic phenomenon among these multi-electron electrocatalytic reactions. Such an analysis provides a useful framework to probe the influence of chemical and electronic modifications on the catalytic steps quantitatively beyond the rate-limiting step.