Energy-band-controlled ZnxCd1-xIn2S4 solid solution coupled with g-C3N4 nanosheets as 2D/2D heterostructure toward efficient photocatalytic H2 evolution

As a sustainable technology, semiconductor photocatalysis has attracted considerable interest in the past decades owing to its potential to relieve energy and environmental issues. By virtue of their unique structural and electronic properties, emerging ultrathin 2D materials show enormous potential to achieve efficient photocatalytic performance. Herein, we report the fabrication of 2D/2D ZnxCd1-xIn2S4/g-C3N4 heterostructure via a facile hydrothermal method for visible-light-driven photocatalytic H-2 evolution. By tailoring the energy band structure of the ZnxCd1-xIn2S4 solid solutions, the position of conduction band can be largely elevated and thus achieve a strong photoreduction capability. A further construction of 2D/2D ZnxCd1-xIn2S4/g-C3N4 heterojunction can reduce charge transfer distance from inner part to surface and create abundant interfacial charge transfer pathways, resulting in significantly boosted migration and separation efficiency of photogenerated charge carriers. Consequently, this energy band engineering effect combined with the advantages of the unique 2D/2D architecture endows the ZnxCd1-xIn2S4/g-C3N4 heterojunction with a remarkable H2 evolution rate of 170.3 mu mol h(-1) under visible-light irradiation (lambda > 420 nm) in the absence of co-catalyst, which is nearly 4.5 and 567.7 times that of Zn1/2Cd1/2In2S4/CN (37.8 mu mol h(-1)) and pure g-C3N4 (0.3 mu mol h(-1)), respectively. Furthermore, the apparent quantum yield (AQY) and the solar-to-hydrogen (STH) energy conversion efficiency over Zn1/2Cd1/2In2S4/CN are 8.5% and 2.6%, respectively. This study sheds light on the potential of integrating the two strategies of energy band modulation and 2D/2D heterojunction into designing semiconductor photo-catalysts for highly efficient solar-to-energy conversion applications.