Indicator/catalyst displacement assay: design of a latent catalyst for the selective detection and degradation of cyanide by Prussian blue analog-modified TiO2 nanoparticles

Abstract

Prussian blue bimetallic analog (PBA)-modified TiO₂ particles (NP1–3) were explored as a new generation of latent catalytic materials for the simultaneous detection and removal of cyanide using the indicator/catalytic displacement approach (ICDA). These PBAs not only act as ‘colored coats’ but also quench the oxidative degradation properties of TiO₂ by facilitating the recombination of its electrons and holes. The obtained results revealed that among common organic/inorganic pollutants (e.g., cyanide, aniline, 1,5-naphthalenedisulfonic acid, benzoic acid, and 4-nitrophenol), only CN⁻ could selectively induce a colorimetric response and the photocatalytic oxidative degradation of TiO₂, while analytes bearing amine, sulfate, carboxylate, and phenol functionalities did not induce any response. These functional materials were also found to be applicable in real water bodies.