In‐situ Construction of Ultra‐Thin Graphitic Carbon Nitride Supported Lanthanum Oxide Nanosheet Heterostructures with Enhanced Photocatalytic Hydrogen Evolution Activity

Abstract The preparation of ultra‐thin graphitic carbon nitride has always been a difficult challenge. Herein, the heterostructure of ultra‐thin graphite carbon nitride (UG−CN) supported lanthanum oxide nanosheets was constructed in situ by the strategy of one‐step calcination and annealing (2D/2D). The thicknesses of UG−CN and LaO were about 2.3 nm and 2.9 nm, respectively. The two types of nanosheets are cross‐stacked with each other, and the strong affinity between atoms leads to the formation of an ultra‐thin 2D/2D hybrid nanomaterial, which has close interface contacts. The strong electron interaction and effective charge separation cause electrons to flow from UG−CN to LaO, then to flow to the Pt promoter to catalyze the H 2 generation reaction. In addition, experimental studies have found that the formation of the ultra‐thin 2D/2D structure is mainly caused by the intercalation of lanthanum nitrate in the lamellar structure and the synergistic effect of the combustion‐supporting NO 3 − accelerating the thermal condensation of melamine during heating. Importantly, the photocatalytic hydrogen evolution rate of LaO/UG−CN reaches 104.1 μmol h −1 , which about 12.2 times greater than that of pristine G−CN (8.5 μmol h −1 ). This work is of significance for the preparation of ultra‐thin graphite carbon nitride in a simple way and the understanding of the corresponding formation mechanism for the composite material.