Integrated tetrahydroxyphthalocyanine-coated graphene decorated with ionic liquid-functionalized gold nanoparticles for highly sensitive and selective electrochemical determination of ascorbic acid in fruit juices

Surface functionalization and the combined utilization of zero‐dimensional and two‐dimensional nanomaterials is an effective method to achieve highly sensitive detection for electrochemical analysis. Using an all-in-one strategy, phthalocyanine, gold nanoparticles, and ionic liquid were successively modified on the graphene surface as a highly integrated electrode modification material. Phthalocyanine can repair the defects of reduced graphene oxide by binding to the graphene structure surface through non-covalent functionalization. The combination of ionic liquid on the surface of gold nanoparticles can enhance their physical and chemical activity while preserving their stability. The obtained phthalocyanine-coated graphene nanosheets decorated with ionic liquid-functionalized gold nanoparticles nanocomposites had enhanced electrocatalysis and conductivity ability, and were used for highly sensitive electrochemical detection of ascorbic acid in fruit juices. Excellent results were obtained for the detection of ascorbic acid in the linear range 0.05 to 50 µmol/L with a detection limit of 6.80 nmol/L (S/N = 3) and a sensitivity of 2.68 μA μM⁻¹ cm⁻², indicated that the proposed sensor strategy with multiple signal amplification can achieve higher detection sensitivity. Furthermore, the sensor was used to quantify ascorbic acid content in grapefruit and orange juice with good selectivity and accuracy. The highly integrated electroactive nanocomposites construction method described may also be used with other electrode modification materials and is anticipated to yield fresh perspectives on the advancement of ultrasensitive detection.

Graphical Abstract