Comprehensive experimental design for regulating the coordination environment of single-atom platinum catalysts and selective hydrogenation

Single-atom catalysts (SACs) have become a research frontier in heterogeneous catalysis owing to their maximum atomic utilization efficiency, uniform active sites, and adjustable electronic properties. Platinum (Pt)-based SACs exhibit superior chemoselective hydrogenation, in which the coordination environment of single atoms of Pt dominantly regulates reactant adsorption and activation. Nevertheless, traditional undergraduate chemistry experimental teaching focuses primarily on the synthesis and performance testing of nanocatalysts. There is a lack of experimental training in atomic-scale active site regulation and in establishing structure–activity relationships. To connect cutting-edge catalysis research with undergraduate experimental teaching, this work develops a comprehensive experiment on modulating the coordination environment of single-atom Pt catalysts to help students understand the correlation between the local coordination structure of Pt and its catalytic performance.

This experiment employs a comprehensive research workflow encompassing catalyst preparation, coordination modulation, multicharacterization, catalytic evaluation, and structure–activity relationship analysis. PtO₂/Fe₂O₃ single-atom catalysts were fabricated via co-precipitation followed by calcination at 400 ℃. The Pt coordination environment was tuned from Pt—O to Pt—N by thermal treatment with NH₃ at 300 ℃ for 10, 60, and 90 min, yielding catalysts denoted as Pt/ Fe₂O₃-N300-X. The structural evolution, electronic states, and metal–support interactions were analyzed via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature-programmed reduction (H₂-TPR) characterizations. The catalytic performance was evaluated through chemoselective hydrogenation with 3-nitrostyrene in a high-pressure batch reactor under mild conditions (40 ℃, 0.5 MPa H₂). The optimal catalyst was further assessed for substrate universality and cycling stability.

XRD results confirmed that the crystalline structure of the Fe₂O₃ support remained intact, and the Pt species underwent atomic dispersion without forming metallic Pt particles after NH₃ treatment. XPS analysis results revealed that the Pt 4f binding energy decreased from 72.8 eV to 71.1 eV with prolonged treatment time, indicating a gradual reduction of the Pt species. This phenomenon was further confirmed by the H₂-TPR test results, which showed that the reduction peak of the Pt species disappeared after long-term NH₃ treatment. Moreover, N 1s XPS quantification confirmed successful Pt—N coordination, with the Pt—N species content increasing from 10 min to 60 min and declining at 90 min. In selective hydrogenation with 3-nitrostyrene, the fresh PtO₂/Fe₂O₃ catalyst exhibited no activity even after treatment for 3 h. In contrast, the Pt/Fe₂O₃-N300-60 catalyst achieved 100% conversion of 3-nitrostyrene within 10 min, with 98.7% selectivity toward 3-aminostyrene and a high turnover frequency of 2549 h⁻¹. The results indicate that catalytic activity declines with shorter and longer treatment times. A distinct volcano-type correlation exists among NH₃ treatment duration, Pt—N content, and catalytic activity, demonstrating that moderate N coordination constructs optimal active sites. Moreover, the optimized catalyst exhibits excellent recyclability and universal applicability for various functionalized nitroarenes.

This experiment introduces frontier research on SAC coordination regulation into undergraduate teaching. By adjusting the NH₃ treatment time, students can modulate Pt coordination configurations and establish the structure–activity relationship. The experiment combines the core knowledge of inorganic, physical, and structural chemistry, enabling students to master catalyst synthesis, data analysis, catalytic evaluation, and multidimensional data correlation. It effectively strengthens students’ scientific research thinking, complex data analysis capabilities, and teamwork awareness. Thus, it provides a practical approach for cultivating high-level innovative skills in chemistry.