Single-atom doping of MoS2 with manganese enables ultrasensitive detection of dopamine: Experimental and computational approach

Two-dimensional transition metal dichalcogenides (TMDs) emerged as a promising platform to construct sensitive biosensors. We report an ultrasensitive electrochemical dopamine sensor based on manganese-doped MoS2 synthesized via a scalable two-step approach (with Mn similar to 2.15 atomic %). Selective dopamine detection is achieved with a detection limit of 50 pM in buffer solution, 5 nM in 10% serum, and 50 nM in artificial sweat. Density functional theory calculations and scanning transmission electron microscopy show that two types of Mn defects are dominant: Mn on top of a Mo atom (Mn-t(opMo)) and Mn substituting a Mo atom (Mn-Mo). At low dopamine concentrations, physisorption on Mn-Mo. dominates. At higher concentrations, dopamine chemisorbs on Mn-topMo, which is consistent with calculations of the dopamine binding energy (2.91 eV for Mn-topMo versus 0.65 eV for Mn-Mo). Our results demonstrate that metal-doped layered materials, such as TMDs, constitute an emergent platform to construct ultrasensitive and tunable biosensors.