Nickel-based heterogeneous catalysts are economical alternatives to traditional Pt or Au-based materials, but their specific activity and stability fall short of these precious metals. Many questions remain regarding the active Ni phase for CO oxidation and how the supporting oxide affects its activity and stability under operating conditions. We demonstrate that CeO₂ aerogel-supported Ni(OH)₂ nanoparticles (NPs) show superior activity compared to Ni(OH)₂ NPs supported by commercial, nanometric CeO₂ powder or TiO₂ aerogels. Ex situ X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy reveal that intimate contact between Ni(OH)₂ NPs and the bonded nanoparticulate CeO₂ network prevents the conversion to NiO seen with larger aerogel-supported aggregates of Ni(OH)₂ NPs and unsupported Ni(OH)₂ NPs. The best stability and activity per mole of Ni is achieved at 2.5 wt % Ni(OH)₂ on the CeO₂ aerogel, which converts 95% of CO at 200 °C and maintains activity after 12 h of continuous reaction under dry or humid feedstreams. Computational analysis indicates that CO has far lower adsorption energy on Ni(OH)₂ compared to NiO, resulting in less poisoning of the active surface sites.

中文翻译：

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CeO2 气凝胶在氧化条件下催化 Ni(OH)2 的弹性

镍基多相催化剂是传统 Pt 或 Au 基材料的经济替代品，但它们的比活性和稳定性不及这些贵金属。关于用于 CO 氧化的活性 Ni 相以及支持氧化物如何影响其在操作条件下的活性和稳定性，仍然存在许多问题。我们证明，与商业、纳米 CeO ₂粉末或 TiO _{2气凝胶支持的 Ni(OH) 2} NPs相比，CeO ₂气凝胶负载的 Ni(OH) ₂纳米颗粒 (NPs) 显示出优异的活性。异位 X 射线光电子能谱和 X 射线吸收近边光谱表明 Ni(OH) _{2之间的紧密接触}NPs 和键合的纳米颗粒 CeO _{2网络阻止了 Ni(OH) 2} NPs 和非支撑 Ni(OH) ₂ NPs的较大气凝胶负载聚集体向 NiO 的转化。每摩尔 Ni 的最佳稳定性和活性在 CeO ₂气凝胶上达到 2.5 wt% Ni(OH) ₂时，其在 200 °C 下转化 95% 的 CO 并在干燥或潮湿的原料流下连续反应 12 小时后保持活性. 计算分析表明，与 NiO 相比，CO 在 Ni(OH) ₂上的吸附能要低得多，从而减少了活性表面位点的中毒。