Static Internal Electric Field in Heterojunctions Composed of O–C3N4 Nanosheets Decorated with NH2-MIL-101(Cr) Nanoparticles for Photocatalytic Hydrogen Evolution

Photocatalytic water decomposition is a cost-effective way to convert sustainable solar energy into chemical energy. While semiconductor photocatalysis has generated considerable interest in photocatalytic hydrogen evolution, it is hampered by fast electron–hole complexation and suboptimal efficiency. Herein, an NH2-MIL-101(Cr)/doped-C3N4 heterojunction possessing a static internal electric field (IEF) is successfully prepared, characterized, and assessed for photocatalytic hydrogen production. The optimized photocatalytic H2 evolution rate of the resultant NH2-MIL-101(Cr)/O–C3N4 is 460 μmol g–1 h–1 under visible light, with an AQY of 2.5% at 450 nm. Spectral evidence indicates that the static IEF facilitates rapid electron transfer from NH2-MIL-101(Cr) to O–C3N4, achieving efficient photogenerated charge separation and a consequent significant enhancement in catalytic activity. This work not only presents a case of construction of an IEF through assembling NH2-MIL-101(Cr) with O–C3N4 but also deepens the insight of the rudimentary mechanisms of the static IEF in heterojunctions for photocatalytic hydrogen evolution.