Kokumai Tathiana M, Ferreira Larissa E R, Strapasson Guilherme B, Pasquale Lea, Manna Liberato, Colombo Massimo, Zanchet Daniela
Institute of Chemistry, University of Campinas, Campinas, SP 13083-970, Brazil.
Brazilian Synchrotron Light Laboratory, CNPEM, Campinas, SP 13083-100, Brazil.
ACS Appl Mater Interfaces. 2025 Mar 5;17(9):13221-13231. doi: 10.1021/acsami.4c21397. Epub 2025 Feb 22.
Modulation-excitation spectroscopy coupled to diffuse reflectance infrared Fourier transform spectroscopy (ME-DRIFTS) was explored in this work to obtain valuable insights into the structure-reactivity relations in nanostructured Pt catalysts for the water-gas shift (WGS) reaction. By using model Pt catalytic systems composed of colloidal Pt nanoparticles (NPs) deposited on CeO (i.e., reducible) and SiO (i.e., nonreducible) supports, it was possible to probe distinct Pt active sites and correlate them to the reaction intermediates and pathways. The analysis revealed that PtNPs/SiO favored the participation of well-coordinated (WC) and under-coordinated (UC) Pt sites in the reaction mechanism. In contrast, on PtNPs/CeO/SiO, the additional involvement of highly under-coordinated (HUC) Pt sites was also observed. Additionally, both fast and slow formate species were identified as active intermediates on the surface of the PtNPs/CeO/SiO catalyst by ME-DRIFTS. More importantly, the faster reaction pathway was correlated to HUC and UC Pt sites, while the slower route was associated with WC Pt sites. Carbonates, on the other hand, were spectators. ME-DRIFTS experimentally demonstrate differences in the participation of Pt active sites according to the support, the involvement of interfacial sites, and the correlation of Pt local coordination to the surface intermediates in the WGS reaction.
本工作探索了调制激发光谱与漫反射红外傅里叶变换光谱联用技术（ME-DRIFTS），以深入了解用于水煤气变换（WGS）反应的纳米结构铂催化剂的结构-反应性关系。通过使用由沉积在CeO（即可还原）和SiO（即不可还原）载体上的胶体铂纳米颗粒（NPs）组成的模型铂催化体系，能够探测不同的铂活性位点，并将它们与反应中间体和反应途径相关联。分析表明，PtNPs/SiO有利于配位良好（WC）和配位不足（UC）的铂位点参与反应机理。相比之下，在PtNPs/CeO/SiO上，还观察到高度配位不足（HUC）的铂位点的额外参与。此外，通过ME-DRIFTS在PtNPs/CeO/SiO催化剂表面鉴定出快速和慢速甲酸物种均为活性中间体。更重要的是，较快的反应途径与HUC和UC铂位点相关，而较慢的途径与WC铂位点相关。另一方面，碳酸盐是旁观者。ME-DRIFTS通过实验证明了在WGS反应中，根据载体不同，铂活性位点参与情况的差异、界面位点的参与情况以及铂局部配位与表面中间体的相关性。
