Thermoelectric-Photoelectrochemical Water Splitting under Concentrated Solar Irradiation

Photoelectrochemicaldevices could play a crucial role toward fuelproduction in a circular economy. Yet, light absorption suffers lossesfrom thermalization and the inability to use low-energy photons. Here,we demonstrate that photoelectrochemical reactors can utilize thiswaste heat by integrating thermoelectric modules, which provide additionalvoltage under concentrated light irradiation. While most single semiconductorsrequire external bias, we already accomplish unassisted water splittingunder 2 sun irradiation by wiring a BiVO4 photoanode toa thermoelectric element, whereas the photocurrent of a perovskite-BiVO4 tandem system is enhanced 1.7-fold at 5 sun. This strategyis particularly suitable for photoanodes with more positive onsetpotentials like hematite, with thermoelectric-perovskite-Fe2O3 systems achieving a 29.7x overall photocurrentincrease at 5 sun over conventional perovskite-Fe2O3 devices without light concentration. This thermal managementapproach provides a universal strategy to facilitate widespread solarfuel production, as light concentration increases output, reducesthe reactor size and cost, and may enhance catalysis.

Automated summary

Photoelectrochemical reactors can utilize waste heat by integrating thermoelectric modules, achieving unassisted water splitting and enhanced photocurrent. This thermal management approach provides a universal strategy for widespread solar fuel production.