In situ photocatalytically enhanced thermogalvanic cells for electricity and hydrogen production

Abstract

High-performance thermogalvanic cells have the potential to convert thermal energy into electricity, but their effectiveness is limited by the low concentration difference of redox ions. We report an in situ photocatalytically enhanced redox reaction that generates hydrogen and oxygen to realize a continuous concentration gradient of redox ions in thermogalvanic devices. A linear relation between thermopower and hydrogen production rate was established as an essential design principle for devices. The system exhibited a thermopower of 8.2 millivolts per kelvin and a solar-to-hydrogen efficiency of up to 0.4%. A large-area generator (112 square centimeters) consisting of 36 units yielded an open-circuit voltage of 4.4 volts and a power of 20.1 milliwatts, as well 0.5 millimoles of hydrogen and 0.2 millimoles of oxygen after 6 hours of outdoor operation.

Thermodynamics of Ionic Thermoelectrics for Low-Grade Heat Harvesting

“…(e) Discharging current, voltage, and power density between the TGC and photocatalytically enhanced hybrid device. From ref , Copyright 2023, reprinted with permission from AAAS.…”

Modulation of charge-transfer behavior via adaptive interface treatment for efficient photoelectrochemical water splitting

“…Solar-driven photoelectrochemical (PEC) water splitting has been broadly regarded as a promising solution for sustainable and decarbonized technology in the quest of green and renewable energy. 1–7 Since TiO 2 photoanodes, researched by Fujishima and Honda, 8,9 were employed to perform water splitting to produce hydrogen, a majority of semiconductors, for example, TiO 2 , 10 α-Fe 2 O 3 , 11–14 Ta 3 N 5 , 15,16 and BiVO 4 , 17–22 have been regarded as ideal photoanodes for PEC water splitting in recent years. Among various candidates, BiVO 4 is the most promising candidate for PEC water oxidation because of a low bandgap (2.4 eV), low cost, and ideal band-edge positions.…”

Thermoelectrocatalysis: an emerging strategy for converting waste heat into chemical energy

“…Further theoretical and experimental studies are essential to validate this mode; ( iv) Thermogalvanic cell mode . Recently, a thermoelectric-gel-based ionic gelatin matrix was proposed to realize a continuous concentration gradient of redox ions at the hot and cold sides, achieving a solar-to-hydrogen water-splitting efficiency of up to 0.4%, accompanied by a simultaneous thermopower of 8.2 mV K −1 [ 7 ]. In the future, the application of double chemically crosslinked networks to ionic thermogalvanic cells may enhance both mechanical toughness and power density [ 8 ], thereby advancing the application of thermogalvanic cells in TECatal.…”

“… Working modes of TECatal systems: (a) hybrid structure mode (right, redrawn from [ 4 ]); (b) single-phase mode (right, redrawn from [ 3 ]); (c) p-n nanojunction mode and (d) thermogalvanic cell mode (redrawn from [ 7 ]). Potential applications of TECatal materials: (e) H 2 production and CO 2 reduction (redrawn from [ 1 ]); (f) tumor therapy; (g) vehicle tail gas treatment; (h) window glass coating for indoor air purification.…”