International Journal of Hydrogen Energy, Vol.45, No.13, 7562-7573, 2020
Cobalt phosphate hydroxide loaded g-C3N4 photocatalysts and its hydrogen production activity
To overcome the low photocatalytic efficiency of bulk g-C3N4, herein, we have designed a novel cobalt phosphate hydroxide loaded graphitic carbon nitride photocatalysts by co-precipitation route. The FESEM and HRTEM analysis revealed that in the presence of the phosphorus compound, the g-C3N4 sheets tend to fold and form a rod-like morphology. The loading of cobalt phosphate hydroxide in g-C3N4 resulted in the redshift of the absorption edge. XRD, FTIR and XPS analysis revealed that cobalt phosphate hydroxide is bonded to g-C3N4 via electrostatic interaction. The cobalt phosphate hydroxide/g-C3N4 photocatalysts was used for photocatalytic hydrogen evolution and produced nearly 1016 mu mol/g of hydrogen in 4 h of reaction time under direct solar light irradiation. This significantly higher activity was accredited to the effective charge carrier separation by cobalt phosphate hydroxide in the photocatalysts, as shown by the photoluminescence and time-resolved photoluminescence (TRPL) measurements. TRPL measurements have shown that Co2PO4OH incorporation in g-C3N4 leads to a 42% higher lifetime of photogenerated charge carriers. In addition, the Co2PO4OH loaded g-C3N4 photocatalysts retains its photostability even after four cycles of reaction without any significant drop in hydrogen production activity. This work provides a facile approach to synthesize highly stable and efficient visible light active cobalt phosphate hydroxide loaded graphitic carbon nitride photo catalysts for solar energy conversion applications. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.