Electrocatalysis at nanostructures: can we build a bridge between theory and experiment?

JUAREZ, M.F.; AVILA, M.; SANTOS, E.; RUDERMAN, A.; QUAINO, P.

Xiamen

Seminario; Seminario Invitado; 2017

Xiamen University

The investigation of promising materials for electrocatalysis using both experimental tools and theoretical models is a big challenge. Nowadays, the advances in the nanotechnology and in computational methods have facilitated the construction of bridges between these two approaches. The expansion of highly sensitive characterization techniques in surface science has allowed a detailed description at an atomic level, and the development of very sophisticated software applying the density functional theory (DFT) has provided realistic explanations. However, there are still some difficulties to achieve the right connections, particularly in electrochemical systems. Reactions occurring at these interfaces are affected by the presence of the solvent and ions, which also makes the characterization more difficult. The electrochemical potential plays a fundamental role in the driving forces of electron transfer and these aspects are not easy to be modelled only by DFT.We have selected some systems that are interesting for the electrocatalysis and discuss their behaviour in a framework of our own theory, which combines a model Hamiltonian with DFT calculations, molecular dynamics and Kinetic Monte Carlo to describe electron transfer reactions in an electrochemical environment. This method is not limited to single crystal surfaces, but the effect of different nanostructures such as steps, overlayers, and alloying can be incorporated as well. The advantage of our combined methodology is that it makes possible to calculate the effect of the electronic structure on the energy of activation, while DFT alone can give very useful information about thermodynamic processes. The other important aspect is that in our model is included the solvent reorganization, which plays a fundamental role in electrochemical reactions. We consider the hydrogen adsorption and evolution reactions as test for the investigations of the electrocatalytic properties, mainly focusing on the Volmer electrochemical step.