A unified model for surface electrocatalysis based on observations with enzymes.

Area of Science:

• Biophysical Chemistry
• Electrocatalysis
• Enzyme Engineering

Background:

• Enzymes function as efficient electrocatalysts, enabling chemical transformations near reversible conditions.
• Electrocatalytic voltammograms of surface-confined enzymes offer unique insights into fundamental electrocatalysis.
• Enzymes, unlike small-molecule catalysts, possess buried active sites, remaining largely unaffected by electrode interfaces.

Purpose of the Study:

• To present a general model for electrocatalysis by surface-confined enzymes.
• To explain the origins of 'catalytic bias' in enzymatic electrocatalysis.
• To highlight considerations for developing advanced surface-confined electrocatalysts.

Main Methods:

• Systematic dissection of complex electrocatalytic processes using enzymes.
• Characterization of enzyme components using diffraction and spectroscopy.
• Optimization of enzyme roles via genetic engineering.
• Application of a general model to recently studied enzymes.

Main Results:

• A model is extended to explain electrocatalysis by surface-confined enzymes.
• Two secondary effects controlling catalytic bias are identified: electron transfer potential and potential-dependent catalyst state interconversions.
• The model provides a framework for understanding and developing enzyme-based electrocatalysts.

Conclusions:

• Catalytic bias in electrocatalysis arises from secondary effects beyond the elementary catalytic cycle.
• Understanding these secondary effects is crucial for designing efficient and selective electrocatalysts.
• The presented model is applicable to various surface-confined enzyme systems.