2, NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore, Singapore
5, School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore, Singapore
4, Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Singapore, Singapore, Singapore
3, ECE, National University of Singapore, Singapore, Singapore, Singapore
Hematite (α-Fe2O3), is a photoanode material candidate for Oxygen Evolution Reaction in a Photo-Electro-Chemical cell (PEC). It has an optical bandgap (~2.1eV) which straddles the water oxidation and reduction potentials, allowing it to drive water splitting by absorbing solar radiation. Its chemical resistance, non-toxicity and low cost, make it a promising material to manufacture hydrogen in an environmentally friendly way. Unfortunately, its poor electrical conductivity, carrier transport dynamics and absorptivity, yield low solar-to-hydrogen conversion.
In my talk, I will present how we have used a special hydrogen treatment to systematically enhance the bulk electronic transport in Hematite Nanorods. We observe that hydrogen doping increases the electronic conductivity of α-Fe2O3, without changing its optical bandgap or its structural properties. Consequently the PEC performance of treated photoanodes is much higher than their pristine counterparts.
The novel hydrogenated phase of α-Fe2O3 is characterised by X-Ray Diffraction, Raman and UV-Vis Spectroscopy, Electron Microscopy and Impedance Spectroscopy. The physics underlying the electronic changes are elucidated by Ultrafast Optical-Pump Probe techniques, X-Ray Absorption and Ab-Initio calculations. Our work paves way to utilizing novel hydrogen induced defect states to systematically enhance functionality of oxide photoanodes.