The construction of a dual direct Z-scheme NiAl LDH/g-C(3)N(4)/Ag(3)PO(4) nanocomposite for enhanced photocatalytic oxygen and hydrogen evolution

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 characterized via XRD, FTIR, SEM, HRTEM, XPS, UV-DRS, and photoelectrochemical measurements. The surface wettability properties of the prepared nanocomposites were measured via contact angle measurements. The application of the NiAl-LDH/g-C(3)N(4)/Ag(3)PO(4) ternary nanocomposite was investigated for photocatalytic overall water splitting under light irradiation. In this work, we found that in the presence of Ag(3)PO(4), the evolution of H(2) and O(2) is high over LCN30, and 2.8- fold (O(2)) and 1.4-fold (H(2)) activity increases can be obtained compared with the use of LCN30 alone. It is proposed that Ag(3)PO(4) is involved in the O(2) evolution reaction during water oxidation and g-C(3)N(4) is 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 H(2) and O(2) evolution abilities of NiAl-LDH/g-C(3)N(4)/Ag(3)PO(4) in comparison with NiAl LDH, g-C(3)N(4), Ag(3)PO(4), and LCN30. The observed improvement in the gas evolution properties of NiAl LDH in the presence of Ag(3)PO(4) is 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 H(2) and O(2) evolution, which are significantly enhanced compared with LCN30 and pure NiAl LDH.