Hydrogen production from organic fatty acids using carbon-doped TiO2 nanoparticles under visible light irradiation

Abstract

The photocatalytic production of H2 using carbon-doped TiO2 (CTiO2) nanoparticles has been investigated in single or mixed systems of organic fatty acids (OFAs) under visible light irradiation, including acetic acid, propionate acid, butyric acid and lactic acid. When OFAs were applied at the same electron density (10 e-eq L−1), the H2 evolution rates followed the order of propionic acid > butyric acid ≈ acetic acid > lactic acid, whereas at the same molar concentration (0.5 mol L−1), that order changed to lactic acid > acetic acid > butyric acid ≈ propionic acid. This result implied that the electron transfer efficiency differed from four OFAs, probably due to their different affinity with CTiO2. O2•− and CH3• partially contributed to OFAs degradation and H2 production. The quantum dynamics simulations of electron transfer revealed that the dominant mechanism of H2 production was direct electron transfer from adsorbed OFAs to CTiO2. This work aims to pursue the synergy of solar energy utilization and conversion of OFAs into H2.