High efficiency water splitting photoanodes composed of nano-structured anatase-rutile TiO2 heterojunctions by pulsed-pressure MOCVD

Abstract

In this article, thin solid films are processed via pulsed-pressure metal organic chemical vapour deposition (PP-MOCVD) on FTO substrates over a range of processing times to produce a range of thicknesses and microstructures. The films are highly nanostructured anatase-rutile TiO2 composite films with unique single crystal dendrites. After annealing, carbon was removed, and materials showed improved water splitting activity; with IPCEs above 80 % in the UV, photocurrents of ~1.2 mA.cm-2 at 1.23 VRHE at 1 sun irradiance and an extension of photoactivity into the visible range. The annealed material exhibits minimal recombination losses and IPCEs amongst the highest reported in the literature; attributed to the formation of a high surface area nanostructured material and synergetic interactions between the anatase and rutile phases.

Process-Induced Nanostructures on Anatase Single Crystals via Pulsed-Pressure MOCVD

“…The pattern also shows that the anatase phase exhibits a strong [220] growth texture. This is consistent with previous studies of pp-MOCVD films [14,18,20,27].…”

“…No evidence for Ti-C was detected by Raman spectroscopy and no bulk titanium carbide phases were identified in XRD. These results are consistent with our previous work, where a uniform distribution of carbon was measured through the films thickness [27].…”

Effect of Growth Parameters on the Photocatalytic Performance of TiO2 Films Prepared by MOCVD

“…From XRD pattern it can be seen that the films are formed only by anatase crystalline phase. 15,27 No evidences of rutile or brookite phases were found. The films grown at 400 °C exhibit the most intense peak at 2θ = 47.8°, which corresponds to [200] of anatase-TiO 2 .…”

“…Prepared by MOCVD synthesis of homogeneous films, important attribute for the study of its photocatalytic properties. Gardecka et al 15 grew TiO 2 films by MOCVD at 525 °C. The obtained films were nanostructured compounds of anataserutile TiO 2 .…”

Effect of Nickel Doping on Phase Transformation of TiO2 Nanotube Arrays

“…However, the photocatalytic property of TiO 2 photocatalysts was limited by the low visible light response and rapid recombination of photogenerated carries . To overcome these problems, various strategies such as ion doping, quantum dot or dye sensitization, noble metal decoration, additional TiO 2 coating, and heterojunction structure were attempted widely and very good effects have been achieved . In these methods, anatase/rutile heterojunction structure is relative environmental friendly, low‐cost and easy to obtain, and has attracted a lot of interests of researchers.…”