Repository logo
 

Model-Based Experimental Investigation of Hydrogenase-Like Electrocatalytic Inactivation and Activation Mechanisms


Type

Thesis

Change log

Authors

Wang, Yian 

Abstract

This thesis describes an experimental design framework study which is focused on the investigation of highly complex electrocatalytic mechanisms. Fully model-based approaches combined with the Butler-Volmer model is employed from a pure theoretical model to a validation of practical chemical reactions. The initial chapters introduce the fundamentals and applications of the electrochemistry. Chapter 1 provides an overview of the electrode processes and the governing physical factors which may limit an electrolysis reaction. In Chapter 2, detailed simulation techniques are introduced to interpret an abstractive system into a mathematic problem then to find an accurate, efficient and stable path to the solution. The results begin in Chapter 3, in which a novel high-order operator-splitting (OS) scheme, with fully implicit finite difference (FIFD) method is first time proposed to numerically solve the stiff nonlinear problems in electrochemistry, particularly in electrocatalysis. The developed algorithm is tested through a series of validations for different electrochemical reactions on large planar electrodes. The model predictions employing this method were verified against a classic two-point time evolution implicit finite difference method for typical electrochemical systems. In Chapter 4, the numerical methods are applied to explore a complex redox system, a recently observed hydrogenase-like reaction. Subtle kinetic and mechanistic information is extracted from the voltammetric behaviour and quantitative mechanistic insights obtained. In Chapter 5, an alternative chronoamperometric voltammetry is introduced to explore the same electrocatalytic system described in Chapter 4 in order to explore some unusual current features observed in the redox chemistry. These stepwise studies support a mechanism for glucose oxidation that proceeds most likely through a complex electrocatalytic (EC’CE) scheme with catalytic steps similar to the ones reported for [NiFe] hydrogenases. The overall mechanism of the molecular inactivation and activation process (IAP) was detailed on the basis of our experimentally validated models and compared to [NiFe] hydrogenase IAP. Our findings offer novel perspectives to design finely optimised catalysts by eliminating the inactivation phenomena.

Description

Date

2018-09-30

Advisors

Fisher, Adrian

Keywords

molecular catalyst, hydrogenase, heterogeneous catalysis, activation and inactivation mechanism, mathematical model, glucose oxidation, finite difference method, operator-splitting

Qualification

Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge