The construction of a dual direct Z-scheme NiAl LDH/g-C3N4/Ag3PO4nanocomposite for enhanced photocatalytic oxygen and hydrogen evolution

Abstract

Dual direct Z-scheme photocatalysts for overall water decomposition have demonstrated strong redox abilities and the efficient separation of photogenerated electron-hole pairs. Overall water splitting utilizing NiAl-LDH-based binary and ternary nanocomposites has been extensively investigated. The synthesized binary and ternary nanocomposites were characterizedviaXRD, FTIR, SEM, HRTEM, XPS, UV-DRS, and photoelectrochemical measurements. The surface wettability properties of the prepared nanocomposites were measuredviacontact angle measurements. The application of the NiAl-LDH/g-C3N4/Ag3PO4ternary nanocomposite was investigated for photocatalytic overall water splitting under light irradiation. In this work, we found that in the presence of Ag3PO4, the evolution of H2and O2is high over LCN30, and 2.8- fold (O2) and 1.4-fold (H2) activity increases can be obtained compared with the use of LCN30 alone. It is proposed that Ag3PO4is involved in the O2evolution reaction during water oxidation and g-C3N4is involved in overall water splitting. Our work not only reports overall water splitting using NiAl-LDH-based nanocomposites but it also provides experimental evidence for understanding the possible reaction process and the mechanism of photocatalytic water splitting. Photoelectrochemical measurements confirmed the better H2and O2evolution abilities of NiAl-LDH/g-C3N4/Ag3PO4in comparison with NiAl LDH, g-C3N4, Ag3PO4, and LCN30. The observed improvement in the gas evolution properties of NiAl LDH in the presence of Ag3PO4is due to the formation of a dual direct Z-scheme, which allows for the easier and faster separation of charge carriers. More importantly, the LCNAP5 heterostructure shows high levels of H2and O2evolution, which are significantly enhanced compared with LCN30 and pure NiAl LDH.