Abstract
Surface complexation modeling (SCM) has been wildly applied in the field of environmental science to simulate and explain the interaction between particulate surfaces and pollutant ions via a stoichiometric reaction based on the thermodynamics. We report herein the application of SCM to manipulate the dispersion of cocatalysts on the surface of hematite. In the preliminary trial in a backer system, observations from TEM images confirm that the pH and loaded Co2+ concentrations lead to either homogeneous distribution or coarse clusters of cobalt cocatalysts on hematite surfaces, which is consistent with our SCM simulation. This can be attributed to adsorption or precipitation of cobalt on the hematite surface. Different distribution of surface cobalt cocatalysts further influence the reactivity of photodegradation of organic dyes (RhB) and photoelectrochemical (PEC) water oxidation. Furthermore, when SCM was applied to decorate hematite electrodes with cobalt-phosphate (Co-Pi) cocatalysts, it was found that Pi also plays an important role in the enhanced PEC performance. This is because surface Pi might induce Co-Pi cocatalysts developing into either a continuous or a mesostructured layer, leading to the latter has the photocurrent two folds higher than the former. Our results substantially demonstrate that the application of SCM can not only manipulate the dispersion of surface cocatalyst on hematite surface but also provide an opportunity to explore the interface phenomenon of this distribution and consequential photocatalytic reactivity of hematite electrodes.