Evaluating high temperature photoelectrocatalysis of TiO2 model photoanode
Sunlight concentration has been demonstrated as one promising strategy for practically photoelectrochemical (PEC) water splitting with exceeding 10% solar-to-hydrogen efficiency. However, the operating temperature of PEC devices, including the electrolyte and photoelectrodes , can be elevated to 65 ℃ naturally due to the concentrated sunlight and the thermal effect of near-infrared light. In this work, high temperature photoelectrocatalysis is evaluated using titanium dioxide (TiO 2 ) photoanode as a model system, which is believed to be one of the most stable semiconductors. During the studied temperature range of 25–65 ℃, a linear increment of photocurrent density with a positive coefficient of 5.02 μA cm −2 K −1 can be observed. The onset potential for water electrolysis shows a significant negative shift by 200 mV. An amorphous titanium hydroxide layer and a number of oxygen vacancies generate on the surface of TiO 2 nanorods , promoting the water oxidation kinetics. During long-term stability testing, the NaOH electrolyte degradation and TiO 2 photocorrosion at high temperatures could cause the decaying photocurrent. This work evaluates the high temperature photoelectrocatalysis of TiO 2 photoanode and reveals the mechanism of temperature effects on TiO 2 model photoanode.
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