CdS QD gels were synthesized from trioctylphosphine oxide-capped CdS QDs following a previously reported electrogelation procedure. Briefly, the trioctylphosphine oxide ligands of QDs were first exchanged with redox-active thioglycolate ligands. Under anodic electrolysis, thiolate ligands are oxidatively removed as disulfides, and CdS QDs are also oxidized to form interparticle dichalcogenide bonds between QDs, forming a three-dimensional QD gel network (Figure ). The synthesized gel has an average crystallite size of ~3.4 nm and UV-vis absorption at ~400 nm, like its colloidal QD precursors (Figure ).