The development of high efficiency oxygen reduction catalysts is of great significance for promoting the large-scale application of fuel cells. However, oxygen reduction reaction (ORR) involves a complex process of multi-step proton electron transfer, and the study of its mechanism is challenging. As a result, the design and preparation of practical catalysts lack rational guidance and rely more on empirical rules. For this bottleneck, our group introduce a surface-enhanced Raman spectroscopic (SERS) “borrowing” strategy for investigating ORR processes catalyzed by Au@PtNi nanoparticles (NPs). The bond vibration of adsorbed peroxide intermediate species (*OOH) was obtained, and the effect of Ni on the interaction between surface Pt and *OOH was studied by varying the Ni content in the alloy. The frequency of the *OOH spectral band has an obvious red-shift with increasing Ni content. Combined with density functional theory (DFT) calculations, we show that Ni-doping can optimize *OOH surface binding on the Pt surface, achieving more efficient electron transfer, thus improving the ORR rate. However, there is a significant material gap between the modal core-shell borrowing strategy and the actual nano-catalyst system. On this basis, AuCu nano-catalysts were assembled on the surface of Au@SiO<sub>2</sub> with high Raman enhancement ability, and the intermediate species involved in ORR reaction process, such as hydroxyl group, were captured by constructing nanosatellite structure, and the molecular configuration and its evolution with electrochemical environment were determined. Direct Raman spectroscopic evidence of key intermediate (*OH) demonstrates that the active site is the combination site of Au and Cu. Moreover, two distinct *OH species are observed on the ordered and disordered structure, and the ordered site is more beneficial for ORR due to its lower affinity to *OH. This work deepens the understanding on the important role of ordering degree on BNs and enables the design of improved catalysts.

Molecular insight of the intermediates on the surface of bimetallic catalysts for improving the oxygen reduction reaction probed using an <i>in situ</i> electrochemical-SERS

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Molecular insight of the intermediates on the surface of bimetallic catalysts for improving the oxygen reduction reaction probed using an in situ electrochemical-SERS