@article{nokey,

title = {Selective anode catalyst for the mitigation of start-up/shut-down induced cathode degradation in proton exchange membrane fuel cells},

author = {B M St\"{u}hmeier and A M Damjanovi\'{c} and K Rodewald and H A Gasteiger},

url = {https://www.sciencedirect.com/science/article/pii/S037877532201549X},

doi = {https://doi.org/10.1016/j.jpowsour.2022.232572},

issn = {0378-7753},

year  = {2023},

date = {2023-02-28},

journal = {Journal of Power Sources},

volume = {558},

pages = {232572},

abstract = {Reducing cathode degradation during start-up and shut-down (SUSD) events is one of the remaining challenges for the widespread application of proton exchange membrane fuel cells (PEMFC). An anode catalyst that is selective for the hydrogen oxidation reaction (HOR) while its activity for the oxygen reduction reaction (ORR) is severely reduced, could substantially prolong the SUSD lifetime of the cathode. Herein, we report on single-cell measurements with a Pt/TiOx/C (x ≤ 2) catalyst that has been shown to be HOR selective by rotating disk electrode (RDE) measurements. The HOR activity of the catalyst was compared to conventional Pt/C by H2-pump measurements at ultra-low loadings. The ORR activity of Pt/TiOx/C was compared to Pt/C anodes with high and low Pt loadings, showing a diminished selectivity in MEA compared to RDE measurements. Unfortunately, the PEMFC performance with the Pt/TiOx/C catalyst was compromised by TiOx dissolution, deduced from voltage loss analysis of the H2/O2 performance curves and by ex-situ SEM/EDX of the MEAs. Finally, the successful mitigation of cathode carbon corrosion was shown over the course of 3200 SUSD cycles, whereby the retention of Pt surface area when using a Pt/TiOx/C anode by far exceeded the improvements expected from the reduced ORR kinetics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Ligand Chemistry of Inorganic Lead Halide Perovskite Nanocrystals},

author = {N Fiuza-Maneiro and K Sun and I L\'{o}pez-Fern\'{a}ndez and S G\'{o}mez-Gra\~{n}a and P M\"{u}ller-Buschbaum and L Polavarapu},

url = {https://doi.org/10.1021/acsenergylett.2c02363},

doi = {10.1021/acsenergylett.2c02363},

year  = {2023},

date = {2023-01-26},

journal = {ACS Energy Letters},

pages = {1152-1191},

abstract = {Lead halide perovskite nanocrystals (LHP NCs) have emerged as next-generation semiconductor materials with outstanding optical and optoelectronic properties. Because of the high surface-to-volume ratio, the optical and optoelectronic performance and the colloidal stability of LHP NCs largely depend on their surface chemistry, especially the ligands and surface termination. On one hand, the capping ligands improve the colloidal stability and luminescence; on the other hand the highly dynamic binding nature of ligands is detrimental to the colloidal stability and photoluminescence of LHP NCs. In addition, the surface functionalization with desired molecules induces new functionalities such as chirality, light harvesting, and triplet sensitization through energy/electron transfer or use as X-ray detectors. In this review, we present the current understanding of an atomic view of the surface chemistry of colloidal LHP NCs, including crystal termination, vacancies, and different types of capping ligands. Furthermore, we discuss the ligand-induced functionalities, including photocatalysis and chirality.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Does cluster encapsulation inhibit sintering? Stabilization of size-selected Pt clusters on Fe $ _3 $ O $ _4 $(001) by SMSI},

author = {S Kaiser and J Plansky and M Krinninger and A Shavorskiy and S Zhu and U Heiz and F Esch and B A J Lechner},

url = {https://arxiv.org/abs/2301.10845},

doi = {https://doi.org/10.48550/arXiv.2301.10845},

year  = {2023},

date = {2023-01-25},

urldate = {2023-01-25},

journal = {arXiv preprint arXiv:2301.10845},

abstract = {The metastability of supported metal nanoparticles limits their application in heterogeneous catalysis at elevated temperatures due to their tendency to sinter. One strategy to overcome these thermodynamic limits on reducible oxide supports is encapsulation via strong metal-support interaction (SMSI). While annealing-induced encapsulation is a well-explored phenomenon for extended nanoparticles, it is as yet unknown whether the same mechanisms hold for sub-nanometer clusters, where concomitant sintering and alloying might play a significant role. In this article, we explore the encapsulation and stability of size-selected Pt5, Pt10 and Pt19 clusters deposited on Fe3O4(001). In a multimodal approach using temperature-programmed desorption (TPD), x-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM), we demonstrate that SMSI indeed leads to the formation of a defective, FeO-like conglomerate encapsulating the clusters. By stepwise annealing up to 1023 K, we observe the succession of encapsulation, cluster coalescence and Ostwald ripening, resulting in square-shaped crystalline Pt particles, independent of the initial cluster sizes. The respective sintering onset temperatures scale with the cluster footprint and thus size. Remarkably, while small encapsulated clusters can still diffuse as a whole, atom detachment and thus Ostwald ripening are successfully suppressed up to 823 K, i.e. 200 K above the H\"{u}ttig temperature that indicates the thermodynamic stability limit.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}