Semiconducting single-walled carbon nanotubes (SWCNTs) exhibit unique photophysical processes from the visible to near-infrared that are ascribed to excitation and decay of excitonic transitions. Here we show that polyelectrolytic dispersants and aqueous electrolytes interact directly with charge carriers in the semiconducting nanotubes, resulting in carrier modulation that can be probed through photoluminescence (PL) intensity and frequency changes. Laser photocarrier generation may therefore induce a potential on the nanotube which interacts, through screening and adsorption, with solvent ions, described by ionic activity in the environment. A systematic exploration of various environmental parameters such as the type of polyelectrolyte dispersant and amphoteric surface is investigated to gain increased sensitivity for eventual use in modern potentiometry. Based upon the nanotube’s demonstrated role in double-layer and pseudo-capacitors, we developed models to explain observed phenomena and propose nanotubes can serve as circuit-free optical electrodes for electroanalytical applications on surfaces and cell membranes.

SVR was partially supported by National Science Foundation (ECCS-1509786)