Immobilization of Co, Mn, Ni and Fe oxide co-catalysts on TiO₂ for photocatalytic water splitting reactions

Abstract

Here we report a systematic study of Co, Mn, Ni and Fe oxides as co-catalysts for HER and OER that were prepared by wet impregnation of the corresponding metal acetylacetonate salts onto a model TiO2 substrate.

Recent Achievements in Development of TiO2-Based Composite Photocatalytic Materials for Solar Driven Water Purification and Water Splitting

“…Photocatalytic water splitting implies a non-spontaneous process, where the light photons are used to break the water molecules assisted by a photocatalyst, which generates photoexcited charge carriers, i.e., e − /h + pairs, delivering them to the solid-liquid interface, where the redox half-reactions of water oxidation and reduction are catalyzed [110,111], analogously, as described above for photocatalytic water treatment. The difference in water splitting is that photogenerated charges (i.e., e − and h + ) need to react with H + as the electron acceptor adsorbed on the photocatalyst surface or within the surrounding electrical double layer of the charged particles in order to generate H 2 [112], instead of O 2 generating O 2…”

Heterostructured CoOx–TiO2 Mesoporous/Photonic Crystal Bilayer Films for Enhanced Visible-Light Harvesting and Photocatalysis

“…Figure 7 compares the obtained reaction rates and for all CoO x -TiO 2 films under visible and UV–Vis illumination. All films presented significant photocatalytic activity under visible light, confirming the positive effect of CoO x nanoclusters on titania’s VLA photocatalytic performance by surface states that enable visible-light activation and interfacial charge transfer that promotes charge separation and/or their cocatalyst action [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 23 ]. Distinct improvements of both reaction rates and were observed for the bilayer CoO x -P25/PC films surpassing the additive result of the constituent layers, indicating significant activity enhancement by the PC supported heterostructure.…”

“…Surface modification of TiO 2 by metal-oxide nanoscale clusters has emerged as a facile yet very efficient method for the development of visible-light-activated (VLA) photocatalysts for solar-driven applications including organic pollutant decomposition and water splitting [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Among wet impregnation routes of different metal salt precursors, chemisorption of the bulky metal acetylacetonate complexes on titania followed by post-thermal decomposition has been an effective approach for the dispersion and controlled loading of molecular-scale metal-oxide nanoclusters on TiO 2 [ 21 ].…”

“…Broadband visible-light activation of TiO 2 nanoparticles was related to the formation of metal–O–Ti interfacial bonds, generating surface states that raise titania’s valence band without introducing intragap defect states of low oxidation potential [ 22 ]. Among the different metal oxocomplex surface-modified titania catalysts, CoO x -TiO 2 presented the highest performance among nanoparticulate systems for the degradation of organic pollutants under visible and UV light [ 23 ] and water oxidation [ 17 , 18 , 19 , 20 ].…”

Brownmillerite‐Type Crystalline Ca2FeCoO5 Ultrasmall Particles with Single‐Nanometer Dimensions as an Active Cocatalyst for Oxygen Photoevolution Reaction

“…As found by the HRTEM, small amount of impurities of cobalt and iron oxides were also formed at R w = 15. However, some researchers reported that cobalt oxides [ 36,37 ] and iron oxides [ 36 ] acted as cocatalysts for OER on TiO 2 . Therefore, it is not probable that the lower photocatalytic activity of CFCO/TiO 2 at R w = 15 was caused by the impurities.…”