Nanocatalysts have shown remarkable potential for various catalytic reactions due to their high specific surface area. But the inherently high surface energy of these nanocatalysts promotes spontaneous growth, leading to their instability under harsh catalytic conditions. Additionally, high-temperature treatment is an important way to prepare nanocatalysts because it can enhance atomic diffusion and generate a wide range of nanocatalysts. Unfortunately, many nanocatalysts suffer from inevitable aggregation and fusion during the high-temperature treatment procedure and thus face challenges in controlling their sizes and morphologies. In recent decades, significant progress has been achieved in synthesizing silica with a controllable thickness and mesoporous structures. The construction of silica on nanocatalysts as a protective shell, including core@shell, yolk@shell, or reverse bubble-ball structures, proves to be an effective strategy to prevent aggregation under harsh catalytic conditions. Furthermore, the subsequent etching of the silica shell, similar to protection/deprotection procedures in organic synthesis, enables the successful synthesis of nanocatalysts with controllable size and morphology under high-temperature conditions.

中文翻译：

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用于保护和可控合成纳米催化剂的二氧化硅封装策略

纳米催化剂由于其高比表面积，在各种催化反应中显示出巨大的潜力。但这些纳米催化剂固有的高表面能会促进自发生长，导致它们在恶劣的催化条件下不稳定。此外，高温处理是制备纳米催化剂的重要方法，因为它可以增强原子扩散并产生多种纳米催化剂。不幸的是，许多纳米催化剂在高温处理过程中不可避免地会发生聚集和融合，因此在控制其尺寸和形态方面面临挑战。近几十年来，在合成具有可控厚度和介孔结构的二氧化硅方面取得了重大进展。在纳米催化剂上构建二氧化硅作为保护壳，包括核@壳、蛋黄@壳或反向气泡球结构，被证明是防止恶劣催化条件下聚集的有效策略。此外，随后对二氧化硅壳进行蚀刻，类似于有机合成中的保护/脱保护程序，使得能够在高温条件下成功合成具有可控尺寸和形貌的纳米催化剂。