Cetyltrimethylammonium bromide – Oleic acid (CTAB-OA) bilayer coated iron oxide nanocrystals for enhanced chromium (VI) photoreduction via ligand-to-metal charge transfer mechanism

Elucidating the Role of Capping Agents in Facet-Dependent Adsorption Performance of Hematite Nanostructures

“…Because adsorption is the first step in the catalytic process, the presence of surface ligands can play an influential role in the catalytic behavior of nanomaterials by distinctly interacting with the target sorbate molecule. Studies have demonstrated that beyond simply controlling the shape and size of the nanomaterial, capping agents can enhance or impede desirable reaction outcomes due to steric, electronic, or solvent interactions. ,,− Sometimes, the presence of surface ligands is advantageous for enhanced performance, and metal (oxides) can be strategically coated or synthesized with capping agents to induce this behavior. , For example, CTAB-coated iron oxide nanoparticles were shown to have specific affinity for Cr­(VI) and a favorable ligand-to-metal charge transfer mechanism, resulting in enhanced Cr­(VI) sorption and photoreduction . However, when the assumption of a clean surface is needed to make facet-dependent structure–property–function assignments, persistent capping agents can play a confounding role. − Beyond merely affecting the performance of materials, the presence of surface ligands obfuscates structure–function relationships on faceted nanomaterials, raising the question whether the observed performance can be attributed to facet dependence or if it can be partially or fully attributed to the presence of capping agents.…”

“…23,24 For example, CTAB-coated iron oxide nanoparticles were shown to have specific affinity for Cr(VI) and a favorable ligand-to-metal charge transfer mechanism, resulting in enhanced Cr(VI) sorption and photoreduction. 25 However, when the assumption of a clean surface is needed to make facet-dependent structure−property−function assignments, persistent capping agents can play a confounding role. 26−28 Beyond merely affecting the performance of materials, the presence of surface ligands obfuscates structure−function relationships on faceted nanomaterials, raising the question whether the observed performance can be attributed to facet dependence or if it can be partially or fully attributed to the presence of capping agents.…”