typical and widely used AIEgen due to its facile synthesis and modification. Among the researches, TPE has been intensively studied with metal ions or metal complexes, including metal ion detection, [7] metal organic gels, [8] nanoparticles, [9] metal-organic frameworks, [10] metal coordination. [11] To the best of our knowledge, AIEgens have been rarely investigated on the surface of metal or alloy, though they have been studied on some other materials' surfaces or interfaces, such as glass, polymer matrix, ice crystals, and biointerfaces. [1,12] Meanwhile, adsorption of organic compounds at metal surface have shown exceptional functionalities and promising applications in catalysis, photovoltaics, energy materials, [13] and corrosion mitigation. As is known, metal corrosion is a ubiquitous and detrimental problem in all walks of life, especially in industry such as oil and gas recovery and processing, acid pickling and marine infrastructures, and water treatment. According to statistics, metal corrosion can cause severe economic losses as high as 2-6% of GDP in many countries each year, along with security incidents and environmental risks. [14] Addition of corrosion inhibitor is a prevalent and effective technique to resist corrosion in industrial operations. As adsorbed onto metal surface, the corrosion inhibitor could form a protective film and segregate the corrosive factors. [14] There are several methods to assess the adsorption film of the inhibitors on metal surface, for example, FTIR, SEM, XPS, AFM, and SERS. Nevertheless, these methods are non-visual and time consuming.Brass, an alloy mainly composed of copper and zinc, is amply used in industries such as petrochemical condensers, heat exchangers, and marine constructions, due to its good mechanical workability, excellent electrical, and thermal conductivity. Brass has a certain resistance to corrosion in some cases, but still corrodes heavily in acidic solutions or other corrosive media containing chloride, nitride, and ammonia if not properly protected. [15] Herein, we design a novel corrosion inhibitor for brass which incorporates a soft Lewis base thiocyanate anion (SCN − ) and a
