pH-Dependent Surface Chemistry from First Principles: Application to the BiVO₄(010)-Water Interface

Area of Science:

• Computational Materials Science
• Surface Chemistry
• Electrochemistry

Background:

• Understanding semiconductor-water interfaces is critical for applications like photocatalysis and energy conversion.
• The pH-dependent behavior of these interfaces influences surface charge, adsorption, and reactivity.
• Accurate theoretical models are needed to predict these interfacial properties.

Purpose of the Study:

• To develop a general theoretical framework for calculating pH-dependent interfacial coverage.
• To determine the acidity of surface sites, pH at the point of zero charge (pH_PZC), and water adsorption modes.
• To apply the methodology to the BiVO₄(010)-water interface.

Main Methods:

• Ab initio electronic structure calculations.
• Molecular dynamics simulations.
• Thermodynamic integration method.

Main Results:

• Calculated pH_PZC for BiVO₄(010) shows excellent agreement with experimental data.
• An ab initio concentration diagram illustrates pH-dependent surface coverage and adsorption species.
• Proton adsorption is significant only in highly acidic conditions; molecular water dominates from pH 2-8; hydroxyl ions dominate above pH 8.2.

Conclusions:

• The developed methodology provides a robust tool for studying semiconductor-water interfaces.
• The findings offer insights into surface charge regulation and water adsorption mechanisms.
• This work advances the predictive capability for designing semiconductor materials for aqueous environments.