Super hydrophilic-electrons acceptor regulated rutile TiO2 nanorods for promoting photocatalytic H2 evolution

Abstract

Photocatalytic H2 evolution from water splitting in liquid–solid two-phase requires an efficient photocatalyst with excellent ability of charge separation and reactant molecular diffusion.In this study, the super hydrophilic-electrons acceptor with abundant –C=O and –OH functional groups were evenly grafted onto rutile TiO2 nanorods surface to speed up the charge separation and water molecular diffusion, respectively. The photocatalytic results showed that the TiO2-CA grafted by citric acid (with three –C=O, three carboxy-(–OH) and one alcohol-(–OH)) presented a 1.48° contact angle and a distinct increased H2-production activity (48.5 mmol·h−1·g−1), whereas the TiO2-PA grafted by propane-1,2,3-tricarboxylicacid (Just lack of one alcohol-(–OH) compared with TiO2-CA) showed a 30.95° contact angle and a decreased H2-production activity (19.3 mmol·h−1·g−1) compared to the unmodified TiO2 (25.8 mmol·h−1·g−1), indicating that the super hydrophilic-electrons acceptor is vitally important to the photocatalytic activity of TiO2. Based on the present results, the carbonyl group (–C=O) possess a stronger reducing capability and act as “electrons acceptor”, while the only alcohol-hydroxyl group (–OH) in TiO2-CA can decrease the mass transfer resistance and serve as “super hydrophilic absorber”. Considering its mild preparation, inexpensive cost, and admirable efficiency, the super hydrophilic-electrons acceptor with dual functional groups regulated TiO2 can become a promising way for potential application in photocatalytic field.