A novel photocatalytic selective oxidative transformation of amines to imines using water as a primary oxidant is achieved under oxygen-free conditions. In the presence a single 1%Pt@TiO2-500 catalyst, the photocatalytic oxidative coupling of benzylamine to N-benzylidenebenzylamine has been efficiently performed using water as an oxidant, in which a 99.8% conversion and a 92.5% selectivity were obtained at room temperature; meanwhile, a certain amount of hydrogen was detected that confirms the simultaneous occurrence of water splitting reaction. Further investigations revealed that the introduction of the Pt element facilitates the formation of O-holes on the surface of TiO2, which efficiently promotes the generation of active oxygen species from water and the following oxidative coupling of benzylamine. Then, the photocatalytic oxidative coupling of various aromatic and aliphatic amines with water as the primary oxidant were also studied, and excellent conversion and high selectivities to corresponding products were attained. Based on the control experiment and the catalytic principle, a possible reaction mechanism is proposed for the oxidative coupling of benzylamine with water as the primary oxidant.
This article presents an integrated strategy that couples high-efficiency photocatalytic degradation with low-cost, rapid detection to overcome the main drawbacks of conventional TiO2-based photocatalysts, including a weak visible-light response, rapid charge–carrier recombination, and reliance on expensive instrumentation for dye concentration detection. Platinum-decorated TiO2(Pt/TiO2) was prepared by photoreduction deposition, and systematic characterization confirmed the successful loading of zero-valent Pt nanoparticles onto the TiO2surface, significantly improving charge separation and extending absorption into the visible region. Methylene blue degradation was quantified under ultraviolet (UV) and simulated sunlight; radical-scavenging tests clarified the reaction pathway. In parallel, smartphone images of the reaction mixture were processed in ImageJto extract red–green–blue (RGB) values, which were related to dye concentration through a partial least-squares (PLS) model validated against reference UV–Vis data. Pt/TiO2removed 95.0% of methylene blue within 20 min of UV irradiation and 90.2% within 160 min of simulated sunlight—31.8% and 19.1% faster, respectively, than pristine TiO2. The RGB-based PLS model achieved a coefficient of determination (R2) of 0.961 for the prediction set. By integrating photocatalysis with smartphone-based colorimetry, the proposed method enables rapid monitoring of organic dyes concentration, providing an intelligent and economical platform for industrial wastewater treatment.
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