UBC Theses and Dissertations
Photoanode development for photoelectrochemical water splitting Leon, Miguel Angel
Abundant materials, cheap synthesis methods and high efficiencies are required for photoelectrodes materials to enable commercial water splitting through photoelectrochemical processes. In this work, the synthesis and improvement through an electrochemical modification of the n-type semiconductor BiVO4 for oxygen evolution is presented. The modification consisted on a dynamic polarization in a three-electrode cell. The pristine and modified BiVO4 were evaluated through electrochemical and photoelectrochemical methods. The modification was found to increase the photocurrent by 80% compared to pristine BiVO₄ at 1.23 V vs RHE and increase in the incident photon-electron conversion efficiency (IPCE) by up to 20% at 400 nm. A photocathode for hydrogen evolution was synthetized and tested along with the BiVO4 photoanode in a two electrode photoelectrochemical cell. Water splitting was obtained without external bias and an improvement of 33% in the solar to hydrogen (STH) efficiency was obtained with the modified material. Based on results gathered through electrochemical, photoelectrochemical and physical-chemical characterization, the modification causes the insertion of hydrogen into the lattice and distorts the crystal structure. Moreover, the amount of V4+ in the photoanode increases and there is OH adsorption in the surface. These results provide evidence for improved overall performance.
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