Design of twin junction with solid solution interface for efficient photocatalytic H₂ production

Heterojunction design is an effective approach to provide built-in electric field for enhancing the charge separation and transfer in semiconductor photocatalysts, however the interface of the junction structures often plays a role of charge trap. Herein, a new class of twin junction photocatalysts with Mn_xCd_1-xS solid solution interface is in-situ synthesized by the principle of the solid solubility limit. The appropriate band alignment and graded solid solution interface between Cd-rich and Mn-rich sulfides provide a gradient built-in electric field and a facilitated channel for the efficient charge separation and transfer. As a result, the obtained twin junction photocatalyst exhibits an excellent photocatalytic activity for hydrogen production in the absence of any cocatalyst. The hydrogen evolution rate of the photocatalyst is as high as 82.4 μmol h⁻¹ with an apparent quantum yield of over 10% under visible-light irradiation, which is about 48 times higher than that of the pristine CdS. The design of twin junction photocatalyst may shed light on the rational construction of novel photocatalyst for efficient solar energy conversion.