Application of surface complexation modeling on modification of hematite surface with cobalt cocatalysts: a potential tool for preparing homogeneously distributed catalysts†
The knowledge required to synthesize homogeneously distributed catalysts on the support surfaces is strongly reliant on understanding the interaction between the catalyst and surface of support, which is identical to the descriptions of interactions between environmental pollutants and adsorbents in the field of environmental chemistry. The connection between catalyst synthesis and environmental chemistry is demonstrated herein by using surface complexation modeling (SCM), whose physical foundation is built on the stoichiometric reaction between one solute and one adsorption site on the surface of adsorbents. As suggested by our simulation and supported by TEM images, the manipulation of either homogeneous distribution or coarse clusters of cobalt cocatalysts over hematite surfaces can be achieved by adjusting the pH and initial Co2+ concentration. This is attributed to the conversion of adsorbed Co2+ or Co(OH)2 precipitates on hematite surfaces. Different surface distributions of cobalt cocatalysts further influence the reactivity of photodegradation of organic dyes and photoelectrochemical reactions, which is strongly dependent on the occurrence of the Fenton reactions or charge transport. Our results not only demonstrate the potential of SCM on guiding the preparation of homogeneously distributed catalysts but also indicate that the abundant amount of knowledge in environmental science could be adopted to design an appropriate protocol for catalyst synthesis.