Turning Water into Chemical Fuels under Sunlight

Supervisors: Dr. Yun Hau Ng, Dr. Jason Scott, Prof. Rose Amal

Abstract:

Splitting water into hydrogen and oxygen under sunlight is the Holy Grail in energy research. In this project, we aim to develop ternary oxide semiconductors which can absorb sunlight and use its excited energy to cleave water into its individual component. Hydrogen gas is the target product.

Novelty and Contribution:

Much research has been directed toward photoelectrochemical (PEC) water splitting using semiconductors owing to its potential to cleanly generate inexhaustible hydrogen (H2) fuel sources from water and solar energy. Although various photoelectrodes for water splitting have been reported, the number of visible-light-responsive oxide photoelectrodes is still limited, for example, WO3, Fe2O3 and BiVO4. Hence, it is of great value to develop visible-light-active photocatalysts that can efficiently exploit the visible light in solar energy conversion reactions. For this purpose, bismuth tungstate (Bi2WO6) and bismuth molybdenate (Bi2MoO6) are of great interest as they have been demonstrated useful for the evolution of O2 from water and the degradation of organic compounds under visible light irradiation. Generally, these oxides thin films are prepared by coating a pre-synthesized oxide particles on an electrode substrate using the spin-coating technique, dip-coating method, or electrostatic self-assembly deposition. There are only limited studies relating to the direct synthesis of Bi2WO6 and Bi2MoO6 films without having particulate as intermediates. The discovery of alternatives in the development of direct film synthesis of this ternary metal oxide is therefore desirable.

Expected Outcome:

This project seeks to develop a direct thin film synthesis method for Bi2WO6 and Bi2MoO6 using an in-house developed electrochemical method. Simple oxides of tungsten and molybdenum will be synthesized via anodization prior to the transformation into the bismuth ternary oxides. The optical and electronic properties of the films will be evaluated to determine its band energy position, which is of great significance in investigating their application in photoelectrochemical water splitting.  Contact Dr Yun Hau Ng for more information

NOTE: possibility to continue project for THESIS A

Reference:

 (1)      S. N. Lou; J. Scott; A. Iwase; R. Amal; Y. H. Ng. Photoelectrochemical Water Oxidation using Bi2MoO6/MoO3 Heterojunction Photoanode. J. Mater. Chem. A2016, 4 (18), 6964-6971.

(2)      H. L. Tan; X. Wen; R. Amal; Y. H. Ng. BiVO4 (010) and (110) Relative Exposure Extent: Governing Factor of Surface Charge Population and Photocatalytic Activity. J. Phys. Chem. Lett.2016, 7 (7), 1400-1405.