Modelling water splitting reactions at the electrochemical interface under operating conditions

Objective

This project will investigate aqueous semiconductor interfaces for water splitting applications, using advanced computational chemistry methods. Green hydrogen, produced from water electrolysis using renewable energy, is expected to play a key role in the energy transition and cover approximately 10% of the EU’s energy needs by 2050. One promising production route is using photoelectrochemical cells (PECs), where photogenerated charge carriers in semiconductor electrodes catalyse the hydrogen and oxygen evolution reactions. However, the commercialization of PECs is hindered by low efficiencies, material instability, and cost. Optimizing the performance of PECs requires a thorough understanding of the solid/electrolyte interface under operating conditions. These systems are challenging to probe experimentally, and most computational studies, while extremely useful, often ignore the experimentally relevant effect of the applied electrode potential. Moreover, the few approaches that allow the incorporation of bias in the simulations, come with several shortcomings, such as relying on implicit solvents or requiring the use of prohibitively large systems for the accurate modelling of semiconductors. With bismuth vanadate (BiVO₄) as our model system, in this project we will leverage recent advances in computational chemistry to (i) develop and apply machine learning interatomic potentials to simulate BiVO₄ in contact with explicit water and selected electrolytes, (ii) examine the impact of electrode potential on interfacial structure and electronic properties, and (iii) explore water oxidation pathways using enhanced sampling techniques. This project will advance the atomic-scale modelling of electrochemical interfaces in realistic conditions through an integrated simulation framework, and will provide valuable insights into interfacial structures, electronic properties, and reaction mechanisms, that will guide the design of efficient, stable photoelectrodes.