Development of Nb2O5/ITIC-4F/CuO hybrid heterojunction nanocomposite for efficient solar-driven photocatalytic hydrogen production

For the sustainable conversion of solar energy to hydrogen energy, solar-driven photocatalytic hydrogen synthesis via water splitting has shown paramount attention as a feasible alternative to traditional fossil fuels. Here, we report the synthesis of a novel heterostructure nanocomposite made of Nb₂O₅/ITIC-4F/CuO to be employed as an efficient solar-driven photocatalyst for enhancing hydrogen generation capacity. The in-situ monoethanolamine-assisted colloidal synthesis leads to the modulation of the morphology and structure of the Nb₂O₅/ITIC-4F/CuO nanocomposite. This synthetic recipe leads to the creation of chemical bonds between the ITIC-4F and the surfaces of the Nb₂O₅ and the CuO nanostructures, thereby reducing the interfacial resistance between the grain boundaries of the formed heterojunction, and the light absorption of the entire system has shifted toward the visible spectrum region. The XPS measurements showed that the LUMO level of the ITIC-4F falls below the LUMO level of CuO and above the LUMO level of Nb₂O₅. These unique features facilitate the charge transfer from CuO to Nb₂O₅ and hinder the electrostatic repulsion between the n-type and p-type electrons. The photoelectrochemical, electrochemical impedance spectroscopy, and optoelectronic measurements revealed that the ITIC-4F provides active sites for effectively gathering photoinduced electrons and reduces the charge-transfer resistance at the electrode/ electrolyte interface. The optimal hydrogen production rate of the Nb₂O₅/ITIC-4F/CuO heterostructure is 187 mmol.h⁻¹.g⁻¹. Interestingly, this hydrogen rate is larger than the CuO/Nb₂O₅ nanocomposite (14 mmol.h⁻¹.g⁻¹) by 10 times under visible-light illumination. Therefore, this study provides a novel heterojunction architecture with precise structural engineering to convert solar energy to chemical energy efficiently.