Thermoelectric materials, which can directly convert a heat flux into electricity via the Seebeck effect, display great potential for recovering low-grade waste heat. In recent years, a new concept termed thermoelectrocatalysis (TECatal) has offered thermoelectric materials a brand-new application scenario: a combination of thermoelectric materials with catalytic processes can directly convert heat flux into chemical energy for the synthesis of high-value chemicals, such as hydrogen peroxide (H₂O₂). It should be noted that the TECatal process is not driven directly by thermal energy. From a thermodynamic perspective, the overall conversion of O₂ and H₂O to H₂O₂ is not spontaneous and cannot proceed solely by heating. Instead, the temperature gradient (ΔT) across the thermoelectric material generates a thermoelectric potential via the Seebeck effect. This potential promotes charge separation and directional carrier migration, enabling spatially separated redox reactions. Therefore, thermal energy is first converted into electrical energy and subsequently into chemical energy, constituting an indirect heat-to-chemical energy conversion pathway.

The work reported in 2024 from Zhang’s group revealed that oxygen-deficient strontium titanate (SrTiO₃), which possesses a suitable band alignment and a large thermoelectric potential induced from a donor doping, exerts an efficient TECatal production of H₂O₂. Nevertheless, constrained by the insufficient electron doping merely from the oxygen vacancy, the thermoelectric potential can be tuned only within a narrow window. Under these conditions, only the oxygen reduction reaction (ORR) half-reaction proceeds efficiently, seriously limiting an overall enhancement in H₂O₂ production performance.

In the latest research from Zhang’s group reported by Frontiers of Materials Science, lanthanum (La) substitution at the Sr site of SrTiO₃ was employed to achieve broad-range modulation of electron doping. La substitution at the Sr site not only increases the charge carrier density in the Ti 3d orbital, thereby enhancing the electrical conductivity of SrTiO₃, but also mitigates electron scattering by reducing ionic impurity and lattice distortion within the TiO₆ octahedra. Furthermore, an optimized level of La substitution generates a sufficient built-in electric field under temperature gradient (ΔT), which promotes the separation of electron‒hole pairs. At the same time, it maintains a favorable band alignment that enables dual pathways for the H₂O₂ production, proceeding concurrently from ORR and water oxidation reaction (WOR). Based on this strategy, the La-substituted SrTiO₃ delivers a stable H₂O₂ production rate of 412 μmol⸱L⁻¹⸱g⁻¹⸱h⁻¹ at the ΔT of 130 °C. Specifically, these results validate that an engineered doping control can overcome the limitation of single-reaction pathway, unlocking the full potential of SrTiO₃ for efficient H₂O₂ production via the TECatal effect. This work also offers a potential strategy for sustainable chemical synthesis by utilizing ubiquitous low-grade thermal energy.


DOI:
10.1007/s11706-026-0768-x