Hydrogen Generation Over Cobalt Containing Microporous Aluminohosphates Photo-Catalyst

Abstract

Novel photo-catalytic materials based on cobalt type aluminophosphate molecular sieves have been elaborated in AEL and AFI structure by hydrothermal method. The photo-catalytic activity of CoAlPO4-5 and CoAlPO4-11 were evaluated for hydrogen production via water reduction under visible irradiation.The synthesizedmaterials werecharacterized thoroughly with respect toelemental analysis, X-Ray diffraction (XRD), scanning electron microscopy(SEM), fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DR), N2 adsorption (BET) and NH3 desorption measurement. Electrical conductivity, electrochemical and photo-electrochemical measurementssuch as cyclic voltammetry, currents-potential, Mott-schottky and Nykist were also studied.SinceAlPO4 materials possess a unique chemical composition as well as structural and micro-morphological characteristics. The photo-catalystshave shown a more negative flat band potential (Vfb = 0.31 eV) and a remarkable surface area -- 183 and 258 m2 g-1 which lead to a better accelerationof the charge (e-/h ) transfer by increasing the number of surface reaction sites.In this approach, hydrogen was produced at atmospheric pressure and a temperature of 50 °C. Under visible light, the photo-catalysts exhibited a good photo-catalytic activity for hydrogen production with a yield of 64 and 1260 µmol g-1min-1 for CoAlPO4-5 and CoAlPO4-11, respectively.

Keywords: CoAlPO4-5, CoAlPO4-11,nano-cobalt oxide,photo-electrochemical, photo-catalysis, hydrogen evolution