Boosting the electrochemcial activity of Fe-MIL-101 via acid modulators for highly sensitive detection of o-nitrophenol

Introducing modulators during the synthesis process has been proved as an efficient strategy to adjust MOFs’ intrinsic catalytic properties. Herein, a series of Fe-MIL-101 with promoted electrochemical activity was synthesized via addition of acetic acid, hydrochloric acid and nitric acid as modulators. Their crystal size, surface area, pore structure and the Fe2+/Fe3+ ratio of Fe-MIL-101 were effectively tailored. Their electrochemical behavior was further investigated to probe the density of Fe2+ active sites and electrochemcial surface area. Importantly, relative to the original MIL-101(Fe), the above modified materials exhibited remarkably boosted electrochemical activity toward the oxidation of o-nitrophenol (o-NP). The phenomenon was evident and originated from the faster electron transfer kinetics and stronger adsorption capacity. Finally, a novel and highly sensitive electrochemical sensing platform for the efficient detection of o-NP was fabricated with a wide linear range (0.036–86.4 μM) and the limit of detection was as low as 0.013 µM, which was comparable or even more sensitive than many other established sensors.