High photocatalytic performance for hydrogen production under visible light on the hetero-junction Pani-ZnO nanoparticles

The present work is devoted to the preparation of the hetero-junction of Polyaniline-Zinc oxide nanoparticles (Pani-ZnONps) and its photo-electrochemistry to assess its photo catalytic properties for the water reduction into hydrogen. The semiconducting characterization of the Pani-ZnONps synthetized by in situ chemical oxidative polymerization was studied for the hydrogen evolution reaction (HER) upon visible light illumination. The forbidden bands E-g (= 1.64 eV, Pani) and (3.20 eV, ZnONPS) were extracted from the UV-Visible diffuse reflectance data. The Electrochemical Impedance Spectroscopy (EIS) showed the predominance of the intrinsic material with a bulk impedance of 71 kU cm(2). The semi conductivity was demonstrated by the capacitance measurements with flat band potentials (E-fb = 0.7 and 0.3 V-SCE) and carriers concentrations (N-A = 1.77 x 10(19) and N-D = 4.80 x 10(20) cm(-3)) respectively for Pani and ZnONPS. The energetic diagram of the hetero-junction Pani-ZnONps predicts electrons injection from Pani to ZnONPS in KOH electrolyte. An improvement of 78% for the evolved hydrogen was obtained, compared to Pani alone; a liberation rate of 61.16 mmol g(-1) min(-1) and a quantum yield of 1.15% were obtained. More interestingly, the photoactivity was fully restored after three consecutive cycles with a zero-deactivation effect, indicating clearly the reusability of the catalyst over several cycles. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.