The interest of nanoparticle-based aerogels—3-dimensional (3D) nanoparticle assemblies of macroscopic sizes—in photocatalysis is mainly their versatility for tailoring properties. However, little is known about the true viability of the aerogels as photocatalysts in part because of their 3D structure that is unusual for this application. Here, we investigate the mass and light transport effectiveness in the whole aerogel network and evaluate their photoactivity. We used anatase-based aerogels as model samples and designed a continuous-flow reactor to perform such analyses. It was found that the photons with suitable energy to initiate the reaction can propagate through the entire monolith because of their diffusive transport, making the 3D network fully active. The mass transport in the aerogels was also effective but is influenced by the reactor design. The aerogels showed promising activity, e.g., Pd-anatase aerogels with a volume of only 0.5 ± 0.04 cm³ generated 92 μmol h⁻¹ of H₂ with an apparent quantum efficiency of 13% at 375 nm.

中文翻译：

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洞察纳米颗粒气凝胶中的光和质量传输：整体式 3D 光催化剂的优势

基于纳米颗粒的气凝胶——宏观尺寸的 3 维 (3D) 纳米颗粒组件——在光催化中的兴趣主要是它们在定制特性方面的多功能性。然而，人们对气凝胶作为光催化剂的真实可行性知之甚少，部分原因是它们的 3D 结构对于该应用来说是不寻常的。在这里，我们研究了整个气凝胶网络中的质量和光传输效率并评估了它们的光活性。我们使用基于锐钛矿的气凝胶作为模型样品，并设计了一个连续流反应器来进行此类分析。发现具有合适能量来引发反应的光子由于它们的扩散传输可以在整个整体中传播，从而使 3D 网络完全活跃。气凝胶中的传质也是有效的，但受反应器设计的影响。气凝胶显示出有希望的活性，例如，体积仅为0.5±0.04 cm ^{3 的}Pd-锐钛矿气凝胶产生92 μmol h ^-1的H ₂，在375 nm处具有13%的表观量子效率。