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The stability of nanoparticles is a major challenge in thermal and electrocatalysis. This is especially true for core-shell nanoparticles where only a few monolayers of noble metal protect the usually non-noble core material. In this work, we utilize the practical nobility concept to engineer stable core-shell nanoparticles with a self-passivating core material. Specifically, tantalum carbide as core material in combination with a 1–3 monolayer thick platinum shell exhibits exceptional stability in aqueous media. The core-shell catalyst shows no sign of structural changes after 10,000 degradation cycles up to 1.0 VRHE. Due to the efficient passivation of tantalum carbide at the solid/liquid interface, the dissolution reduces by a factor of eight compared to bare Pt. Our findings confirm that passivating core materials are highly beneficial for the stabilization of core-shell nanomaterials in aqueous media. They open up new ways for the rational design of cost-efficient but stable non-noble core – platinum shell nanoparticles where harsh, oxidizing conditions are employed

115 p.-4 fig.-45 fig. supl.-14 tab supl., Mixed plastics waste represents an abundant and largely untapped feedstock for the production of valuable products. The chemical diversity and complexity of thesematerials, however, present major barriers to realizing this opportunity. In this work, we show that metal-catalyzed autoxidation depolymerizes comingled polymers into a mixture of oxygenated small molecules that are advantaged substrates for biological conversion. We engineer a robust soil bacterium, Pseudomonas putida, to funnel these oxygenated compounds into a single exemplary chemical product, either b-ketoadipate or polyhydroxyalkanoates. This hybrid process establishes a strategy for the selective conversion of mixed plastics waste into useful chemical products., Funding was provided by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office (AMO), and Bioenergy Technologies Office (BETO). This work was performed as part of the BOTTLE Consortium and was supported by AMO and BETO under contract no. DE-AC36- 08GO28308 with the National Renewable Energy Laboratory (NREL),operated by the Alliance for Sustainable Energy, LLC. The BOTTLE Consortium includes members from MIT, funded under contract no. DE-AC36-08GO28308 with NREL. Contributions by S.S.S. were supported by the US Department of Energy, Office of Basic Energy Sciences, under award no. DEFG02-05ER15690.