Activation of Water‐Splitting Photocatalysts by Loading with Ultrafine Rh–Cr Mixed‐Oxide Cocatalyst Nanoparticles

Abstract

The activity of many water‐splitting photocatalysts could be improved by the use of RhIII–CrIII mixed oxide (Rh2−xCrxO3) particles as cocatalysts. Although further improvement of water‐splitting activity could be achieved if the size of the Rh2−xCrxO3 particles was decreased further, it is difficult to load ultrafine (<2 nm) Rh2−xCrxO3 particles onto a photocatalyst by using conventional loading methods. In this study, a new loading method was successfully established and was used to load Rh2−xCrxO3 particles with a size of approximately 1.3 nm and a narrow size distribution onto a BaLa4Ti4O15 photocatalyst. The obtained photocatalyst exhibited an apparent quantum yield of 16 %, which is the highest achieved for BaLa4Ti4O15 to date. Thus, the developed loading technique of Rh2−xCrxO3 particles is extremely effective at improving the activity of the water‐splitting photocatalyst BaLa4Ti4O15. This method is expected to be extended to other advanced water‐splitting photocatalysts to achieve higher quantum yields.

Creation of active water-splitting photocatalysts by controlling cocatalysts using atomically precise metal nanoclusters

“…Moreover, it was confirmed that both the reverse reaction ( Figure 20C) and O 2 -photoreduction reaction ( Figure 20D) were well suppressed over this sample, as expected. 270 These results indicate that loading Rh 2−x Cr x O 3 NCs using our method is very effective for creating highly functional water-splitting photocatalysts. The method of loading Rh 2−x Cr x O 3 NCs established in this study can be applied to other photocatalysts in principle.…”

“…The obtained photocatalyst exhibited an apparent quantum yield of 16% (excitation wavelength = 270 nm; Figure 30), which is the highest achieved for BaLa 4 Ti 4 O 15 to date. 270 For this photocatalyst, almost no decrease in activity and no increase in particle size were observed even after 10 h of water-splitting reaction ( Figure 29D(b)). Moreover, it was confirmed that both the reverse reaction ( Figure 20C) and O 2 -photoreduction reaction ( Figure 20D) were well suppressed over this sample, as expected.…”

“…Various structural analyses revealed that approximately 6 Rh 2 (SG) 2 complexes aggregated during adsorption. 270 Then, Rh-SG/Cr 2 O 3 /BaLa 4 Ti 4 O 15 was calcined at 300 °C under reduced pressure to remove the ligands from the Rh-SG complexes and form a solid solution of Rh and Cr oxides ( Figure 29BC). Finally, a small amount of Cr with a slightly higher oxidation state was reduced to Cr III by UV light irradiation ( Figure 28E).…”

Controlled colloidal metal nanoparticles and nanoclusters: recent applications as cocatalysts for improving photocatalytic water-splitting activity

“…[204][205][206][207] If ultrane Rh 2Àx Cr x O 3 NCs could be loaded on the photocatalyst as an HER cocatalyst, it might be possible to activate the photocatalyst further. Very recently, Kurashige et al 208 attempted to load ne Rh 2Àx Cr x O 3 NCs as an HER cocatalyst on BaLa 4 Ti 4 O 15 by modifying the method shown in Fig. 16A.…”

CrOx-mediated Performance Enhancement of Ni/NiO-Mg:SrTiO3 in Photocatalytic Water Splitting

“…Rh, is also likely. 1,14,15 Ni/NiO co-catalysts are another type of often employed co-catalysts enabling photocatalytic overall water splitting. Similarly to CrO x in Rh/CrO x , a NiO-shell is believed to prevent oxygen reduction to occur on the metallic Ni core.…”