Improved photocatalytic hydrogen production property over Ni/NiO/N-TiO2-x heterojunction nanocomposite prepared by NH3 plasma treatment

A series of visible light responsive Ni/NiO/N-TiO2-x heterojunction nanocomposites are prepared by nonthermal NH3 plasma treatment. X-ray diffraction, N-2 adsorption, UV-Vis spectroscopy, Electrochemical impedance spectroscopy, Photoluminescence, and X-ray photoelectron spectroscopy are used to characterize the prepared nanocomposites. Ni species deposition decreases the surface free energy of nanocomposites, reduce the thermodynamic driving force for particle growth, thus leading to the smaller particle sizes. NH3 plasma treatment do not influence the crystal structure but shift its absorption edges to the visible light region, reduce partial NiO to metallic Ni, and form high concentration of oxygen vacancies. H-2 production performances on prepared TiO2 nanocomposites are evaluated under visible light irradiation using CH3OH as scavenger. The results indicate that Ni-0/Ni2+ ratio plays a significantly important role on the photocatalytic H-2 production ability. Adequate oxygen vacancies concentration can improve the visible light utilization, leading to an enhanced photocatalytic performance. The prepared R -Ni(0.03)N(10)Ti exhibited the highest H-2 production ability (1210 mu mol h(-1)) and apparent quantum yield (7.5%), which is 250 times higher than that of neat TiO2. The possible mechanism is proposed. (C) 2013 Elsevier B.V. All rights reserved.