光催化已成为一种有前途且环境可持续的解决方案,可通过乙醇光反应产生高纯度氢气。人们普遍认为,添加助催化剂,尤其是贵金属,显著增强了半导体的催化活性。然而,贵金属如Pt的高成本可能会限制这一新兴技术的实际应用。在这里,我们评估了通过在预形成的半导体纳米颗粒之间创建适当的界面来减少贵金属负载的可能性。商业二氧化钛(P25)由于其商业可用性而被选为半导体,促进我们结果的直接验证和佐证。选择Pt作为助催化剂是因为用于乙醇光重整的最有效的光催化剂之一仍然基于P25与Pt的组合使用。我们报告说,当使用非常低的Pt负载量(≤0.05wt%)时,诱导聚集体的产生显着改善了产生的总氢气。我们开发了一种开创性的反应器,旨在在液相中纳米颗粒悬浮液的真实操作条件下进行光致发光研究。这种方法使我们能够从P25附聚物中获得平均光致发光发射,这是不可能通过使用标准固体样品支架获得的。多亏了这些设备,我们可以得出的结论是,活性的这种显着改善主要是由于形成了有利于聚集体颗粒之间电荷转移的界面。据此,团聚体的二氧化钛纳米颗粒充当天线以收集太阳光的光子并产生将被转移到位于相同团聚体中的铂纳米颗粒的光激发电子。相比之下,具有低Pt负载量的原始P25将具有大量没有铂的二氧化钛纳米颗粒,因此,inactive.该结果在用于实际未来光催化反应器的固定化光催化系统的情况下尤其相关,因为半导体的固定将产生与我们的方法产生的相互作用相似的相互作用。因此,最初的半导体固定和随后的助催化剂的光沉积成为显著降低助催化剂含量的有希望的方法。
Photocatalysis has emerged as a promising and environmentally sustainable solution to produce high-purity hydrogen through ethanol photoreforming. It is commonly accepted that adding co-catalysts, especially noble metals, significantly enhances the catalytic activity of semiconductors. However, the high cost of noble metals such as Pt may limit the real application of this emerging technology. Here we evaluate the possibility of reducing the noble metal loading by creating the appropriate interface between pre-formed semiconductor nanoparticles. Commercial titania (P25) was selected as the semiconductor due to its commercial availability, facilitating the straightforward validation and corroboration of our results. Pt was selected as co-catalyst because one of the most efficient photocatalysts for the ethanol photo-reforming is still based on the use of P25 in combination with Pt. We report that the creation of induced aggregates dramatically improves the total hydrogen produced when very low loadings (≤0.05 wt%) of Pt are used. We have developed a pioneering reactor designed for conducting photoluminescence studies under authentic operational conditions of nanoparticle suspensions in the liquid phase. This approach allows us to obtain the average photoluminescence emission from the P25 agglomerates what it would be impossible to obtain by using standard solid samples holders. Thanks to this equipment, we can conclude that this remarkable improvement of the activity is mainly due to creation of an interface that favors the charge transfer between the particles of the aggregates. According to this, the titania nanoparticles of the agglomerates act as an antenna to collect the photons of the sun-light and produce the photo-excited electrons that will be transferred to the platinum nanoparticles located in the same agglomeration. In contrast, raw P25 with low loadings of Pt would have a high number of titania nanoparticles without platinum, and therefore, inactive. This result would be especially relevant in the case of immobilized photocatalytic systems for real future photocatalytic reactors because the immobilization of the semiconductors would generate similar interactions to the one created by our method. Consequently, the initial semiconductor immobilization followed by the subsequent photo-deposition of the co-catalyst emerges as a promising approach for a substantial reduction of the co-catalyst content.