Metal–organic framework functionalized sulphur doped graphene: a promising platform for selective and sensitive electrochemical sensing of acetaminophen, dopamine and H2O2

Abstract

We present a simple in situ self-assembly approach for crafting a heteroatom doped graphene supported metal–organic framework (MOF) nanocomposite, which is a highly conductive redox active 2D platform with excellent potential for selective and sensitive electrochemical sensing of biologically important molecules. The hybrid nanocomposite comprises of 1,4-benzene dicarboxylic acid organic linker based Cu-MOF self-assembled over sulfur doped graphene nanosheets (S-Gr). Our detailed structural characterization and electrochemical investigations carried over the so-crafted Cu-MOF@S-Gr composite suggest that S-Gr sheets, besides inducing a directional growth of MOF crystals, endow this nanohybrid with numerous electroactive sites. The synergism between the Cu-MOF and S-Gr components and the presence of too many electroactive sites facilitate faster heterogeneous electron transfer and mass transfer, thereby imparting Cu-MOF@S-Gr with excellent conductivity, electrocatalytic activity and electroanalytical utility. The excellent electroanalytical utility of the Cu-MOF@S-Gr hybrid nanocomposite was explored toward selective and sensitive sensing of acetaminophen (AC), dopamine (DA) and H₂O₂. We demonstrate that using the Cu-MOF@S-Gr hybrid nanocomposite, AC and DA can be electrochemically sensed with a resolution of 2.22 and a sensitivity of 0.85 μA μM⁻¹ cm⁻² and 0.58 μA μM⁻¹ cm⁻² in the concentration ranges of 2 μM to 98 μM and 10 μM to 80 μM with detection limits as low as 12.00 ± 0.05 nM and 37.00 ± 0.06 nM, respectively. We also demonstrate that with the Cu-MOF@S-Gr hybrid, H₂O₂ can be electrochemically sensed in the concentration range as low as 0.1–3.0 μM with an extremely low detection limit of 11.3 ± 0.04 nM and a very high sensitivity of 63.82 μA μM⁻¹ cm⁻². We opine that the present study will stimulate an intense research activity toward the design of highly sensitive, selective and stable MOF based electroanalytical devices.