Title
Fabrication of a Co(OH)2/ZnCr LDH “p–n” Heterojunction Photocatalyst with Enhanced Separation of Charge Carriers for Efficient Visible-Light-Driven H2 and O2 Evolution
Author
Dipti Prava Sahoo, Susanginee Nayak, K. Hemalata Reddy, Satyabadi Martha, Kulamani Parida
Year
2018
Journal
Inorganic Chemistry
Abstract
Photocatalytic generation of H2 and O2 by water splitting remains a great challenge for clean and sustainable energy. Taking into the consideration promising heterojunction photocatalysts, analogous energy issues have been mitigated to a meaningful extent. Herein, we have architectured a highly efficient bifunctional heterojunction material, i.e., p-type Co(OH)2 platelets with an n-type ZnCr layered double hydroxide (LDH) by an ultrasonication method. Primarily, the Mott–Schottky measurements confirmed the n- and p-type semiconductive properties of LDH and CH material, respectively, with the construction of a p–n heterojunction. The high resolution transmission electron microscopy results suggest that surface modification of ZnCr LDH by Co(OH)2 hexagonal platelets could form a fabulous p–n interfacial region that significantly decreases the energy barrier for O2 and H2 production by effectively separating and transporting photoinduced charge carriers, leading to enhanced photoreactivity. A deep investigation into the mechanism shows that a 30 wt % Co(OH)2-modified ZnCr LDH sample liberates maximum H2 and O2 production in 2 h, i.e., 1115 and 560 μmol, with apparent conversion efficiencies of H2 and O2evolution of 13.12% and 6.25%, respectively. Remarkable photocatalytic activity with energetic charge pair transfer capability was illustrated by electrochemical impedance spectroscopy, linear sweep voltammetry, and photoluminescence spectra. The present study clearly suggests that low-cost Co(OH)2 platelets are the most crucial semiconductors to provide a new p–n heterojunction photocatalyst for photocatalytic H2 and O2 production on the platform of ZnCr LDH.
Instrument
FP-8300
Keywords
Photoluminescence, Chemical stability, Inorganic chemistry, Semiconductor, Materials