An enhanced sensitivity towards H₂O₂ reduction based on a novel Cu metal–organic framework and acetylene black modified electrode

Highlights: • A novel Cu metal–organic framework (Cu-MOF) has been synthesized under hydrothermal condition. • The Cu-MOF modified electrode shows good electrocatalytic activity towards H₂O₂ reduction in alkaline solution. • The addition of acetylene black improves the response performance of the modified electrode towards H₂O₂ reduction. - Abstract: As a large class of highly crystalline hybrid materials, metal-organic frameworks (MOFs) have the potentials to act as electrochemical sensors due to their active metal sites and diverse structures. However, the poor electron-conductive property limits their application as electrocatalyst. An effective strategy is to introduce conductive phases to the MOFs. In this paper, a novel Cu metal–organic framework {[Cu₂(bep)(ada)₂]·H₂O}_n (Cu-MOF) (beb = 1,4-bis(2-ethylbenzimidazol-1-ylmethyl) benzene, H₂ada = 1,3-adamantanediacetic acid) was synthesized under hydrothermal condition. Single-crystal X-ray analysis revealed that the Cu-MOF was a three-dimensional pillar-layered framework with two kinds of paddle-wheel secondary building units. Subsequently, the Cu-MOF modified glassy carbon electrode (GCE) was applied in the H₂O₂ detection in alkaline solution, and it exhibited the good electrocatalytic activity towards H₂O₂ reduction. When acetylene black (AB) was added to the Cu-MOF, the electrocatalytic performance of the Cu-MOF modified electrode was greatly improved. The results of amperometric response to H₂O₂ with different AB addition showed that the Cu-MOF/AB-2%/GCE exhibited a wide linear relationship in the H₂O₂ concentration range of 0.05–3 μM with a rather high sensitivity of 5.56 μA μM⁻¹ cm⁻², a low detection limit of 0.014 μM as well as a fast response time of 4 s. The Cu-MOF/AB-2%/GCE also exhibited the good selectivity towards H₂O₂ reduction, and had no response to its normal co-existences of glucose, glycerin, alcohol and lactose. In addition, the modified electrode showed a good stability in the test period.