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Platinum functions exceptionally well as a nanoparticulate catalyst in many important fields, such as in the removal of atmospheric pollutants, but it is scarce, expensive and not always sufficiently durable. Here, we report a perovskite system in which 0.5 wt% Pt is integrated into the support and its subsequent conversion through exsolution to achieve a resilient catalyst. Owing to the instability of most Pt oxides at high temperatures, a thermally stable platinum oxide precursor, barium platinate, was used to preserve the platinum as an oxide during the solid-state synthesis in an approach akin to the Trojan horse legend. By tailoring the procedure, it is possible to produce a uniform equilibrated structure with active emergent Pt nanoparticles strongly embedded in the perovskite surface that display better CO oxidation activity and stability than those of conventionally prepared Pt catalysts. This catalyst was further evaluated for a variety of reactions under realistic test environments—CO and NO oxidation, diesel oxidation catalysis and ammonia slip reactions were investigated. Nanoparticulate platinum is a highly active catalyst, but it is scarce, expensive and not always sufficiently durable. Now, barium platinate has been used as a vehicle to preserve platinum as an oxide during the solid-state synthesis of a Pt-doped titanate perovskite; this enables the production of a structure with active and stable Pt nanoparticles on the perovskite surface that catalyses CO oxidation.

Topological states of matter exhibit many novel properties due to the presence of robust topological invariants such as the Chern index. These global characteristics pertain to the system as a whole and are not locally defined. However, local topological markers can distinguish between topological phases, and they can vary in space. In equilibrium, we show that the topological marker can be used to extract the critical behaviour of topological phase transitions. Out of equilibrium, we show that the topological marker spreads via a flow of currents emanating from the sample boundaries, and with a bounded maximum propagation speed. We discuss the possibilities for measuring the topological marker and its flow in experiment.