Ceria and gold co-decorated porous MoS2@graphene nanocomposite electrochemical electrode integrated with smartphone-controlled microstation for simultaneous dual metal ions detection

Continuous increase in release of toxic metals into ecosystem posed a threat to public ecology, leading to demand for the portable monitoring system to control contamination source and monitor disease progression. Herein, ceria and gold co-decorated porous MoS2@graphene nanocomposite was synthesized to construct electrochemical chip and integrate with smartphone-controlled hand-held microstation for simultaneous detecting Zn(II) and Cu(II). Concretely, MoS2 nanosheets coated polyimide were firstly laser-induced into 3D frame-structured MoS2/graphene with abundant oxygen-containing groups and active breaking edges, thereby accelerating the electron transfer and improving the absorptivity and reductive affinity for divalent ions. Double electro-deposition of ceria and gold provide vast oxygen vacancies for sensing, and Ce(III)/Ce(IV) cycle inhibit the recombination of electrons and holes, prolonging the life of carriers to enhance its electro-conductibility. The hydroxylation of ceria under acidic conditions is favorable for ions adsorption. Benefitting from synergetic effect among materials, the smartphone-controlled sensing system exhibits high sensitivity and low detection limit for Cu(II) of 2.8 ppt and Zn(II) of 103.6 ppt. Low energy barrier of target plating/stripping kinetics were also substantiated via calculating activation energy upon composite using Arrhenius formula. Furthermore, its outstanding flexibility, reusability, and anti-interference performance was verified, indicating the potential implementation possibilities in complex environment.