Solar thermal-activated photocatalysis for hydrogen production and aqueous triethanolamine polymerization

Abstract

The photocatalytic process plays a vital role in the direct conversion and storage of renewable solar energy into green hydrogen (H₂) fuel, a long-term and sustainable technology pathway with the potential for limiting the growth of global carbon emissions. However, the kinetics of H₂ production and photogenerated hole reactions are sluggish, which limit the intrinsic photoelectrochemical attributes of semiconductor materials, thus lowering the conversion efficiency of solar energy. Herein, we report a heterogeneous solar thermal activated photocatalysis (STAP) strategy for H₂ production and triethanolamine (TEOA) polymerization initiated by highly active photogenerated electron–hole pairs. Under simulated solar light irradiation, solar thermal activation elevated the reaction temperature up to 40.7 °C with a 76.7 mmol g⁻¹ h⁻¹ photocatalytic H₂ evolution (PHE) rate, which was 6.31 times faster than that at 11.1 °C (12.16 mmol g⁻¹ h⁻¹), ascribed to the solar thermal energy promoting H₂ desorption from the surface of platinum (Pt)-deposited graphitic carbon nitride (g-C₃N₄/Pt). The detailed DFT calculations reveal that the solar thermal energy contributes significantly to activating the H₂ desorption kinetics by reducing the energy barrier (ΔG_D) of H₂ desorption from the Pt-carbon nitride (Pt-CN) active site and diminishing the bond-dissociation energy (kcal mol⁻¹) of the Pt–H bond. Furthermore, the STAP-optimized g-C₃N₄-T/Pt improved the PHE rate up to 92.1 mmol g⁻¹ h⁻¹, which was close to the level of commercial TiO₂ (P25) at 104.0 mmol g⁻¹ h⁻¹. Besides, we also found that STAP facilitates aqueous TEOA polymerization, thus favoring the high-efficiency utilization of excited-state holes toward mediating green synthesis.