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The graphite-phase carbon nitride (g-C 3 N 4) photocatalytic materials were prepared by one-step calcination method to degrade methylene blue (MB) and potassium butyl xanthate (PBX) under visible light irradiation. The prepared g-C 3 N 4 photocatalytic materials were investigated in detail by various characterizations, and the experiments showed that the graphitic phase carbon nitride photocatalytic materials were successfully prepared by the one-step calcination method. The material possesses excellent optical properties and strong visible light absorption, thus achieving photocatalytic degradation of MB and PBX. The catalyst dosage, pH, the initial concentration of pollutants have important effects on photocatalytic activity of MB and PBX. The photocatalytic degradation efficiency was 98.99% for MB and 96.83% for PBX under the optimal conditions (catalyst dosage, initial pollutant concentration and pH value were 500 mg L−1, 20 mg L−1 and 7, respevtively). The photocatalytic mechanisms on MB and PBX were elucidated. ·OH was the key specie for MB, while ·O 2 − was the key specie for PBX. This study advances the development of photocatalytic technology for mineral wastewater. [Display omitted] • g-C 3 N 4 photocatalyst was prepared by pyrolysis. • The separation of photogenerated electron-hole pairs lead to high efficiency. • Superoxide radicals and hydroxyl radicals are the main reactive groups. [ABSTRACT FROM AUTHOR]

Porous Au@Pt nanoparticles (NPs) with electron-rich Pt shells exhibited significantly enhanced peroxidase-like activity by changing the catalytic reaction path, which offered valuable opportunities to construct sensitive colorimetric biosensors, as exemplified by detection of spike 1 protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). [Display omitted] The development of colorimetric assays for rapid and accurate diagnosis of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is of practical importance for point-of-care (POC) testing. Here we report the colorimetric detection of spike (S1) protein of SARS-CoV-2 based on excellent peroxidase-like activity of Au@Pt nanoparticles, with merits of rapidness, easy operation, and high sensitivity. The Au@Pt NPs were fabricated by a facile seed-mediated growth approach, in which spherical Au NPs were premade as seeds, followed by the Pt growth on Au seeds, producing uniform, monodispersed and porous Au@Pt core–shell NPs. The as-obtained Au@Pt NPs showed a remarkable enhancement in the peroxidase-mimic catalysis, which well abided by the typical Michaelis-Menten theory. The enhanced catalysis of Au@Pt NPs was ascribed to the porous nanostructure and formed electron-rich Pt shells, which enabled the catalytic pathway to switch from hydroxyl radical generation to electron transfer process. On a basis of these findings, a colorimetric assay of spike (S1) protein of SARS-CoV-2 was established, with a linear detection range of 10–100 ng mL−1 of protein concentration and a low limit of detection (LOD) of 11 ng mL−1. The work presents a novel strategy for diagnosis of COVID-19 based on metallic nanozyme-catalysis. [ABSTRACT FROM AUTHOR]