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DOI: 10.1002/adma. 201404314 amphoteric substance, which reacts with both acids and bases. To achieve superior control using ALD, area-selective deposition can be done, taking advantage of the high sensitivity of the process to substrate surface conditions.[11b, 12] Doing this requires surface functional groups to be manipulated or patterned in advance of material deposition, resulting in areaselective ALD. The materials are deposited only where needed using area-selective ALD, which avoids blocking the active site of catalysts by deposited materials. The use of highly stable supports is another way to improve Pt stability. Numerous investigations have been carried out to improve the activity and durability of Pt catalysts. For instance, much effort has been devoted to develop novel durable catalyst support materials such as nitrogen-doped carbon nanotube (NCNT),[13] and ceramic support.[1c, 14] Recently, NCNTs have been reported as support materials in fuel cell catalysts.[5b, 15] NCNTs not only exhibit higher electrochemical corrosion resistance than carbon black [13] but also improve Pt catalytic activity toward ORR.[16] In addition, it has been proven that the NCNT can favor the ALD process due to their defective surface, which is an ideal support for the growth of ALD metal or metal oxide.[17]

Here, we demonstrate a facile approach to stabilize Pt catalysts encapsulated in stable zirconia nanocages by area-selective ALD. The Pt NPs were encapsulated in zirconia nanocages to enhance Pt stability and activity. An outline of the synthetic strategy for the Pt encapsulated in zirconia nanocage is depicted in Figure 1. Pt NPs were initially …