Synthesis and photocatalytic property for H2 production of H1.78Sr0.78Bi0.22Nb2O7 nanosheets

The SrBi 2 Nb 2 O 9 platelets with a thickness of about 600   nm were synthesized by molten salt synthesis method. The treatment of the SrBi 2 Nb 2 O 9 platelets with hydrochloric acid resulted in the formation of the protonated H 1.78 Sr 0.78 Bi 0.22 Nb 2 O 7 platelets. Through a top–down approach in ethylamine solution, the H 1.78 Sr 0.78 Bi 0.22 Nb 2 O 7 platelets were exfoliated into H 1.78 Sr 0.78 Bi 0.22 Nb 2 O 7 nanosheets with a thickness of about 2.6   nm. The evolution of the structure, composition, morphology, optical, and photocatalytic properties of SrBi 2 Nb 2 O 9 platelets was studied as it is converted into H 1.78 Sr 0.78 Bi 0.22 Nb 2 O 7 platelets and subsequently exfoliated into H 1.78 Sr 0.78 Bi 0.22 Nb 2 O 7 nanosheets. The absorption edge shifts to a lower wavelength accompanied by the protonation and exfoliation. The photocatalytic H 2 evolution of the three samples were evaluated under the irradiation of a 300   W Xenon lamp from CH 3 OH/H 2 O solution, indicating that H 1.78 Sr 0.78 Bi 0.22 Nb 2 O 7 nanosheets Exhibit 5.5 and 26.2 times higher activity than that of the H 1.78 Sr 0.78 Bi 0.22 Nb 2 O 7 and SrBi 2 Nb 2 O 9 platelets, respectively. The enhanced activity for the H 1.78 Sr 0.78 Bi 0.22 Nb 2 O 7 nanosheets is mainly attributed to the higher separation efficiency of the photogenerated carriers and the larger specific surface area caused by the significant reduction in thickness.