Reasonable design and optimization of photocatalyst structure is an important strategy to realize sustainable hydrogen production. The rational design and interfacial tuning of Z-scheme heterojunctions remain challenging. Herein, a series of hollow cage-like Zn0.01Co0.99Se2/ZnIn2S4 Z-scheme heterojunction photocatalysts templated by cobalt-based bimetallic organic frameworks is successfully obtained via a hydrothermal approach. As expected, the optimized catalysts exhibit excellent hydrogen production performance without noble metal co-catalysts, which is mainly attributable to the synergistic effect of abundant active sites, strong light trapping and effective charge separation. Spectroscopic characterization and density functional theory (DFT) calculations indicate that the doping of Zn ions leading to more photogenerated carriers and faster charge transfer rates inside the heterojunction is another key factor in improving the catalytic performance. This work provides a feasible strategy for the optimization and design of Z-scheme heterojunctions through structural and interfacial engineering.

Photosynthesis with the chloroplast works efficiently because of the envelope structure that serves to carry enzymes and to simultaneously maintain the spatial separation of photosynthesis and cellular respiration. Inspired by the spatially separated architecture, a chloroplast-like structured photocatalyst (PdS@CdS@MoS2), in which the PdS and MoS2 function as enzymes in the chloroplast and CdS shell functions as the chloroplast envelope, was developed to improve the photocatalytic H-2 evolution. In this unique nanoscale bionic structure, the poriferous CdS shell enhances light absorption, generates photoinduced carriers, and separates oxidation and reduction reactions. Meanwhile, PdS and MoS2 dual cocatalysts enhance the charge separation efficiency through forming a built-in electric field with CdS. We demonstrate that the separation efficiency of carriers, carrier lifetime, and the yield of H-2 are both higher than that of CdS nanoparticles, evidencing the feasibility of the chloroplast-like structure in enhancing the photocatalyst activity. This work emphasizes the synergism of the three key processes of the photocatalytic reaction by simulating the chloroplast structure and provides a general synthesis strategy, the synthesis of novel structured for photocatalysts for diverse applications in the energy field.

2D Sb2MoO6 was designed as a Z-scheme heterojunction in the construction of the 2D hybridized g-C3N4/Sb2MoO6/Bi2O3 dual Z-scheme structure.

CdS demonstrate superior potential for H-2 production, but exist deficiencies of low carrier separation efficiency and photostability limit their large-scale application. Hence, a novel Ag2S/CdS/Cd2SO4(OH)(2) composite has been designed. In-depth measurements reveal that Cd2SO4(OH)(2) will be in-situ reduced to Cd metal as an excellent electron trap and hydrogen production site during the photocatalytic process. As a result, photogenerated electrons and holes will directionally transfer to Cd metal and Ag2S respectively, leading to the separation of oxidation and reduction reaction sites. As expected, Ag2S/CdS/Cd2SO4(OH)(2) and final Ag2S/CdS/Cd systems exhibit considerably promoted photocatalyst properties than many other CdS-based photocatalysts no matter on the illumination of UV, Vis or NIP light. The research not only provide a new insight to develop a low-cost, carrier spatial separation and full-spectrum-responsive photocatalytic hydrogen evolution system, but also displays a novel strategy for in-situ deposition of metal clusters on the photocatalyst surface during the photocatalytic process.