Studying the surface of heterogeneous photocatalysts has been a long-standing challenge in the catalysis community. This project investigates the effect of surface loading on the properties and performance of colloidal photocatalysts. Using detailed spectroscopic analyses, this research addresses challenges with catalysis and will help understand how surface engineering influences the properties of photocatalysts in different organic solvents. These studies will help improve the synthesis of complex organic compounds and high recovery rates for the photocatalysts used for catalyzing reactions. To synthesize our photocatalyst particles, (3-Aminopropyl)triethoxysilane (APTES) was bound to silica particles before covalently attaching the photocatalyst perylene tetracarboxylic acid dianhydride (PTCDA). The photocatalysts were characterized using several spectroscopic and chemical analyses. To assess the performance of these catalysts, the oxidation of sulfide to sulfoxide with the PTCDA-bound modified silica was tested in a photoreactor using 450 nm blue LED light over 12 hours. This reaction has wide applications in the synthesis of commercial pharmaceutical drugs, making it the best reaction to test these silica particles. The photocatalytic oxidation of sulfide was monitored by thin layer chromatography and nuclear magnetic resonance. The catalytic performance at varying photocatalyst loading on silica was tested. Analyses of these data showed a faster rate with lower photocatalyst concentration, which is the opposite of expected results. A plausible reason for this observation could be attributed to the effect of photocatalyst loading on their excited state lifetimes. Excited states of photocatalysts can be more effectively quenched at higher surface concentrations, leading to poor catalytic performance. To test this hypothesis, the surface loading–photophysical property relationships will be further assessed. Moreover, careful photochemical studies were performed to confirm that both the photocatalyst and the light illumination were required to drive sulfide oxidation. With this collected data, more experiments will be conducted to test the reproducibility of observed outcomes.