The development of an effective method for detecting heavy-metal ions remains a serious task because of their high toxicity to public health and environments. Herein, a new electrochemical method based on a graphene aerogel (GA) and metal–organic framework (MOF) composites was developed for simultaneous detection of multiple heavy-metal ions in aqueous solutions. The GA-MOF composites were synthesized via the in situ growth of the MOF UiO-66-NH2 crystal on the GA matrix. GA not only serves as the backbone for UiO-66-NH2 but also enhances the conductivity of the composites by accelerating the electron transfer in the matrix. UiO-66-NH2 worked as a binding site for heavy-metal ions because of the interaction between hydrophilic groups and metal cations. The detection performance of the GA-UiO-66-NH2 composite-modified electrodes was determined. The developed electrochemical method can be successfully applied for individual and simultaneous detection of heavy-metal ions, namely, Cd2+, Pb2+, Cu2+,and Hg2+, in aqueous solutions with high sensitivity and selectivity. The method can also be used for simultaneous detection of Cd2+, Pb2+, Cu2+, and Hg2+ in river water and the leaching solutions of soil and vegetable with high accuracy and reliability. This work provides a new approach for simultaneous detection of multiple heavy-metal ions in practical applications.

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Materials that have both conductivity and photocatalytic activity are widely applied in electrical devices and as environmental pollution handles. Based on such requirements, phosphorus and aluminium co-doped conductive zinc oxide nanocrystals (PAZO NCs) with novel visible-light catalytic activities have been mass produced by the combustion method. The PAZO NCs have diameters of 30-100 nm and BET specific surface areas of 15.27-18.99 m 2 g -1 . These PAZO NCs exhibited novel photocatalytic activity and good conductivity [the powder conductivity was (0.98-1.76) ϫ[a] 3708 10 -4 S cm -1 ], the reason being mainly attributed to the increase in carrier concentration and defects through P and Al co-doping. In addition, we found that the 3PAZO NCs, in which the molar ratio of Zn to P atoms is 100:3, had the best visible-light catalytic efficiency of the PAZO NCs, and the size of PAZO NCs decreased with increasing doping of phosphorus and aluminium. This study is useful as a reference for the mass production of modified ZnO NCs and its applications, such as in environmental management, photocatalysis, and anti-static electricity.