Green and regulable synthesis of CdNCN on CdS semiconductor: Atomic-level heterostructures for enhanced photocatalytic hydrogen evolution
Taiyu Huang, Zimo Huang, Xixian Yang, Siyuan Yang, Qiongzhi Gao, Xin Cai, Yingju Liu, Yueping Fang, Shanqing Zhang, Shengsen Zhang
Abstract
In the realm of photoenergy conversion, the scarcity of efficient light-driven semiconductors poses a significant obstacle to the advancement of photocatalysis, highlighting the critical need for researchers to explore novel semiconductor materials. Herein, we present the inaugural synthesis of a novel semiconductor, CdNCN, under mild conditions, while shedding light on its formation mechanism. By effectively harnessing the [NCN] 2 ⁻ moiety in the thiourea process, we successfully achieve the one-pot synthesis of CdNCN-CdS heterostructure photocatalysts. Notably, the optimal CdNCN-CdS sample demonstrates a hydrogen evolution rate of 14.7 mmol g −1 h −1 under visible light irradiation, establishing itself as the most efficient catalyst among all reported CdS-based composites without any cocatalysts. This outstanding hydrogen evolution performance of CdNCN-CdS primarily arises from two key factors: i) the establishment of an atomic-level N-Cd-S heterostructure at the interface between CdNCN and CdS, which facilitating highly efficient electron transfer; ii) the directed transfer of electrons to the (110) crystal plane of CdNCN, promoting optimal hydrogen adsorption and active participation in the hydrogen evolution reaction. This study provides a new method for synthesizing CdNCN materials and offers insights into the design and preparation of innovative atomic-level composite semiconductor photocatalysts. In this work, a novel utilization mechanism of thiourea molecules is presented. A CdNCN-CdS composite photocatalyst with an atomic-level heterostructure (NCN-Cd-S) is successfully synthesized by exploiting the concentration gradient of thiourea dissociation products in space-time. Benefiting from the strong electron affinity of the CdNCN and the excellent electron transfer pathways provided by the atomic-level heterostructure at the interface, the composite heterostructure demonstrates superior photocatalytic hydrogen evolution performance.