Photocatalytic Hydrogen Evolution Using Ni–Pd/TiO 2 : Correlation of Light Absorption, Charge-Carrier Dynamics, and Quantum Efficiency

• Published in: Journal of physical chemistry. C Vol. 121; no. 26; pp. 14302 - 14311
• Main Authors: Luna, Ana L., Dragoe, Diana, Wang, Kunlei, Beaunier, Patricia, Kowalska, Ewa, Ohtani, Bunsho, Bahena Uribe, Daniel, Valenzuela, Miguel A., Remita, Hynd, Colbeau-Justin, Christophe
• Format: Journal Article
• Language: English
• Published: American Chemical Society 06-07-2017
• Subjects: Chemical Sciences; HYDROXYL RADICALS; NANOPARTICLES; RADIOLYSIS; CLUSTERS; AU-PD; RATE CONSTANTS; SURFACE MODIFICATION; WATER-TREATMENT; CATALYSTS; TIO2
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.7b01167

TiO2 surface modification with bimetallic nano particles (NPs) has demonstrated to be a strategy to enhance the hydrogen generation via photocatalysis and to minimize the use of expensive noble metals. A better understanding of the role of bimetallic NPs is of crucial importance to design efficient photocatalysts. Here, we show a systematic study of surface modification of commercial TiO2 (P25) with mono and bimetallic (Ni, Pd, and Ni-Pd) NPs synthesized by radiolysis. The photocatalysts were characterized by High Resolution Transmission Microscopy (HRTEM), Scanning Transmission Electron Microscope (STEM), X-ray Diffraction (XRD), Energy-Dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), and UV-vis Diffuse Reflectance Spectroscopy (DRS). The charge-carrier dynamics was studied by Time Resolved Microwave Conductivity (TRMC). The photocatalytic activity was evaluated for hydrogen generation under UV-vis irradiation using polychromatic and monochromatic lights (action spectra analysis of apparent quantum efficiency). TiO2 modified with Pd-Ni bimetallic NPs exhibits a high activity for H-2 generation, and a synergetic effect of the two metals was obtained. The study of light absorption, charge-carrier dynamics, and photocatalytic activity revealed that the main role of the metal NPs is to act as catalytic sites for recombination of atomic hydrogen.