Towards the scale-up of TiO 2 -based photoanodes for water splitting Beatriz Silva-Gaspar (1) , Lorenzo Lombard i (2) , Gaspard Bouteau (3) , Maxime Dufond (3) , Dmitry Aldakov (2) , Laurent Baraton (3) , Murielle Chavarot-Kerlidou (1) and Vincent Artero (1) (1) Univ. Grenoble Alpes, CEA, CNRS, LCBM, Grenoble, France, (2) Univ. Grenoble Alpes, CEA, CNRS, SyMMES, Grenoble, France, (3) Engie Lab Crigen, 4 Rue Joséphine Baker, 93240 Stains, France The current social and energy context requires the development of sustainable energy sources that allow for pollution mitigation and diversify energy sources. Since the solar radiation that reaches the Earth far exceeds humanity's energy needs, the development of technology that allows for its efficient harnessing and use is currently seen as an alternative to the current energy pool. One possible application is the generation of hydrogen through the water splitting reaction, thereby enabling the utilization and storage of solar energy. Photoelectrochemical (PEC) water splitting is being widely investigated for such applications. Since its first use in 1972 [1, 2] , TiO 2 has been broadly used as a photoanode due to its low cost, non-toxic nature, and stability in liquid solutions. However, this oxide has some limitations, namely its high band gap value and high recombination charge rate [3] . To address these issues, in this work, we synthesized and characterized TiO 2 nanorod-based electrodes using a hydrothermal method [4] . Subsequently, they were reduced electrochemically. Upon reduction, the photocurrent was increased from 0,7 mA/cm² to 1,3 mA/cm² at a neutral pH. To increase interaction with incident solar radiation, electrode sensitization was performed by immobilisation of inorganic semiconductor nanocrystals – quantum dots (QDs). Heavy-metal-free CuInGaS2 QDs were deposited into the TiO 2 electrodes. The TiO 2 sensitized electrodes show a photocurrent of 1,2 mA/cm² at a neutral pH and stability up to 8 hours. Lastly, a Co- based catalyst was deposited to improve the oxygen evolution reaction (OER) performance [5] . An onset reduction and a photocurrent increase were observed. These promising results pave the way towards the scale-up of such photoanodes. References 1. Fujishima, A., Honda, K.. Electrochemical Photolysis of Water at a Semiconductor Electrode. Nature, 238, 37-38 (1972) 2. Fujishima, A., Kohayakawa, K., Honda, K. Hydrogen Production under Sunlight with an Electrochemical Photocell. J. Electrochem. Soc., 122, 1487-1789 (1975) 3. Feng, T., Yam, F. K. A review of TiO2 nanostructured materials for hydrogen generation through photocatalytic and photoelectrochemical water splitting. Phys. Rev. B Condens. 417466, (2025). 4. Nguyen, M., Kim, K. Analysis on growth mechanism of TiO2 nanorod structures on FTO glass in hydrothermal process. JIEC. 104, 445-457 (2021) 5. Artero, V. et al. A Janus cobalt-based catalytic material for electro-splitting of water. Nat. Mat. 11, 802-807 (2012).
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