Sustainable Phthalocyanine-Modified TiO2 Nanofilm as a Light-Operated Nanozyme for Colorimetric Determination of L‑Penicillamine

Although nanozyme-based colorimetric sensors have been studied, there is still a great challenge of light-operated colorimetric sensors constructed by sustainable nanozymes. Herein, we have first prepared the sustainable 2(3), 9(10), 16(17), 23(24)-octamethoxyphthalocyanine (Pc­(OH)8)-modified TiO2 films on a glass substrate as light-operated nanozymes. Interestingly, the peroxidase-like activity of Pc­(OH)8-TiO2 nanofilms can be tuned by the light irradiation. Pc­(OH)8-TiO2 nanofilms exhibit the higher peroxidase-like activity under the light irradiation than that of pure TiO2. Moreover, the active species including •O2 – and h+ play an important role in enhancing the catalytic activity of Pc­(OH)8-TiO2 by virtue of the synergistic effect of Pc­(OH)8 as an organic conductor and TiO2 as an inorganic semiconductor. Other than the light-operated colorimetric reaction, another advantage is the facile placement of Pc­(OH)8-TiO2 nanofilms into or out of the reaction solutions, avoiding of being discarded carelessly and thus benefiting sustainable development. Furthermore, a sustainable colorimetric platform has been operated by the light irradiation for determining H2O2 and L-penicillamine (LPA) in good linear ranges of 40–100 and 6–10 μM with limit of detection (LOD) of 4.68 and 0.842 μM, respectively. This work can provide guidelines to synthesize high-activity nanozymes for hazardous substance detection and material sustainability.