Rational synthesis of highly efficient dual–Z–scheme InVO4/FeVO4/Ex–CQDs–g–C3N4 heterojunction for photo(electro)chemical water splitting and pollutant removal applications

Background

The ever–growing concern for environmental pollution and the need for clean energy sources have driven research toward sustainable technologies. Semiconductor photocatalysis has emerged as a promising approach for both environmental remediation and clean energy generation due to its efficiency and environment–friendly nature. This work focuses on developing a novel photocatalyst capable of addressing two crucial environmental challenges: Cr(VI) removal and water splitting for clean hydrogen production.

Methods

This study presents the development of a dual–Z–scheme heterojunction photo(electro)catalyst based on a combination of metal vanadates (FeVO₄ and InVO₄) and ultrasound–exfoliated carbon–rich graphitic carbon nitride (Ex–C–g–CN), denoted as IVO/FVO/Ex–C–g–CN. The synthesized nanocomposite was thoroughly characterized using various spectroscopic and microscopic techniques (such as XRD, XPS, UV–DRS, FESEM, EDX, and PL) to understand its material properties and structure. These techniques are crucial for elucidating the relationship between the composition of the material and its photocatalytic performance.

Significant findings

The key innovation of this work lies in the design of the dual–Z–scheme heterojunction within the IVO/FVO/Ex–C–g–CN photo(electro)catalyst. This design fosters efficient separation of photogenerated charges, a critical factor for enhancing photocatalytic activity. The effectiveness of this approach is evident in the achieved removal efficiency of 97.17 % for 100 ppm Cr(VI) within just 60 min of visible light irradiation. This demonstrates the superior ability of the developed photocatalyst to address chromium contamination. Furthermore, the photocatalyst exhibits a remarkable photocurrent of 3.16 mA and a low onset potential of 112 mV for the photoelectrochemical oxygen evolution (OER) reaction. These findings highlight the potential of this material for solar–driven water splitting, a clean and sustainable method for hydrogen production. Additionally, the IVO/FVO/Ex–C–g–CN composite demonstrates excellent recyclability, maintaining high Cr(VI) removal efficiency over multiple cycles, indicating its reusability and cost-effectiveness. Overall, the exceptional photo(electro)catalytic performance of the IVO/FVO/Ex–C–g–CN dual–Z–scheme heterojunction positions it as a promising candidate for tackling environmental pollution and generating clean energy.