Au/TiO₂ 2D‐Photonic Crystals as UV–Visible Photocatalysts for H₂ Production

Abstract

Noble metal decoration of wideband gap semiconductors enables the excitation of surface plasmons in the visible range that upon relaxation generate hot carriers used for catalysis. However, this strategy leads to photocatalytic conversion efficiencies that are still low. Here, a light‐trapping scheme is used to amplify the light‐harvesting efficiency of the TiO2 semiconductor beyond the UV region by coupling a 2D‐photonic crystal to Au decorated titania. This approach is easily scalable using soft nanoimprinting lithography to prepare Au/TiO2 2D‐photonic photocatalysts. In a first process, gold nanoparticles (Au NPs) are in situ infiltrated in the superficial 50 nm of a mesoporous titania (mTiO2) scaffold patterned with the photonic structure, while in a second one 2D‐photonic crystals with a homogeneous volume distribution of the Au colloids are achieved. The dependence of the optical properties of the photonic crystals on the lattice parameter, geometry, and metal loading is presented through extinction measurements and analyzed through simulations. The improved photocatalytic performance of the substrates is tested for hydrogen production where a maximum of 8.5 mmol gcat−1 h−1 of H2 is recorded and attributed to photonic–plasmonic effects. These results may open new avenues in solar harvesting for hydrogen production using photonic crystals as photocatalysts.

Mechanistic Investigation of Alkali‐Treated Photocatalytic CO2 Reduction: The Role of OH− and Metal Cations for Almost 100 % Selectivity of CO

“…The results obtained via Ultraviolet‐vis diffuse reflectance spectroscopy (DRS) were shown in Figure 4a, b. Commercial P25 exhibited a characteristic UV absorption feature in the range of 200 to 400 nm, demonstrating that it could absorb photons and be excited to generate electrons/holes [33] . Typically, the charge pairs could participate in CO 2 reduction and produced CO or CH 4 .…”

“…Commercial P25 exhibited a characteristic UV absorption feature in the range of 200 to 400 nm, demonstrating that it could absorb photons and be excited to generate electrons/holes. [33] Typically, the charge pairs could participate in CO 2 reduction and produced CO or CH 4 . When P25/Pt was treated by KOH, the area and intensity of the absorption peaks remained unchanged, indicating that the alkali treatment did not affect the optical properties of the photocatalysts.…”

Pre- and post-assembly modifications of colloidal plasmonic arrays: the effect of size distribution, composition and annealing

“…24 Moreover, several applications have been targeted using templated self-assembled structures, including surface-enhanced Raman scattering, 25,26 tumor monitoring, 27 and catalysis. 28 An interesting direction that remained relatively unexplored by the community is the possibility to modify optical properties of the plasmonic arrays acting on the internal structure of the repeating unit. This perspective is especially interesting for colloidal assemblies, as these modifications can potentially be pre-designed into the colloidal building-blocks used for the assembly, exploiting directional surface chemistry, specific interaction with the substrates, as well as crystallinity or chemical reactivity.…”

“…24 Moreover, several applications have been targeted using templated self-assembled structures, including surface-enhanced Raman scattering, 25,26 tumor monitoring, 27 and catalysis. 28…”

PtS quantum dots/Nb2O5 nanosheets with accelerated charge transfer for boosting photocatalytic H2 production

“…[7][8][9][10][11] The introduction of cocatalysts can improve the charge separation and transfer capacity, reduce the activation energy related to the hydrogen generation reaction, and generate massive adsorption and reaction active sites, thus boosting the photocatalytic hydrogen generation performance. [12][13][14] With regard to the cocatalyst design, the selection of appropriate cocatalysts is crucial in improving the photocatalytic H 2 evolution performance. 15,16 Pt and other noble-metal materials are generally considered as efficient cocatalysts for photocatalytic hydrogen production; however their scarce source and expensive preparation costs limit their actual application for photocatalytic hydrogen evolution.…”