New mechanisms were found for the formation of metal oxide microspheres with yolk–shell and filled structures by applying carbonaceous template microspheres with high porosity. Repeated impregnation first adopted to achieve a high loading rate of metal precursor in the carbonaceous template provided the breakthrough. The carbonaceous template with an appropriate loading rate of the metal precursor produced metal oxide microspheres with filled and yolk–shell structure depending on the ramping rate and oxygen concentration during the post-treatment process. Combustion of the carbonaceous template—which occurs during the moderate post-treatment process in air with a high oxygen concentration—must occur to form yolk–shell structured microspheres. On the other hand, the decomposition of carbon by post-treatment at a slow ramping rate in an atmosphere with a low oxygen concentration without burning produced filled-structured metal oxide microspheres. The carbonaceous template with a high loading rate of the metal precursor produced metal oxide microspheres with filled structures even at a fast ramping rate and high oxygen concentration during the post-treatment process. The new strategy was applied to synthesize various metal oxide microspheres including SnO₂, Fe₂O₃, NiO, and Mn₂O₃ microspheres.

中文翻译：

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通过应用碳质模板来合成填充的和卵壳结构的金属氧化物微球的新通用方法

通过使用高孔隙率的碳质模板微球，发现了形成卵黄壳和填充结构的金属氧化物微球的新机制。首次采用重复浸渍以实现碳质模板中金属前体的高负载率提供了突破。含碳模板具有适当的金属前体负载率，这取决于后处理过程中的升温速率和氧浓度，会生成具有填充的卵黄壳结构的金属氧化物微球。碳质模板的燃烧（发生在适度的后处理过程中，在空气中的氧气浓度很高）必须发生，以形成卵黄壳结构的微球。另一方面，通过在低氧浓度的气氛中以缓慢的升温速率进行后处理而分解碳，而不会燃烧生成的填充结构的金属氧化物微球。具有较高金属前体负载率的碳质模板即使在后处理过程中也能以快速的升温速率和高的氧气浓度生产出具有填充结构的金属氧化物微球。该新策略被用于合成包括SnO在内的各种金属氧化物微球_{如图2所示}，Fe ₂ O ₃，NiO和Mn ₂ O ₃微球。