An S-scheme artificial photosynthetic system with H-TiO₂/g-C₃N₄ heterojunction coupled with MXene boosts solar H₂ evolution

Solar hydrogen production via water splitting is pivotal for solar energy harnessing, addressing key challenges in energy and environmental sustainability. However, two critical issues persist with single-component photocatalysts: suboptimal carrier transport and inadequate light absorption. While heterojunction-based artificial photosynthetic systems like Z-scheme photocatalysts have been explored, their charge recombination and light harvesting efficiency are still unsatisfactory. S-scheme heterojunctions have gained attention in photocatalysis, owing to their pronounced built-in electric field and superior redox capabilities. In this study, we introduce a MXene-based S-scheme H-TiO₂/g-C₃N₄/Ti₃C₂ heterojunction (TCMX), synthesized through electrostatic self-assembly. The as-prepared TCMX exhibited an excellent photocatalytic hydrogen evolution rate of 53.67 mmol g⁻¹ h⁻¹ surpassing the performance of commercial Rutile TiO₂, H-TiO₂, g-C₃N₄, and HTCN. The effectiveness of TCMX is largely due to the built-in electric field in the S-scheme heterojunction and the cocatalytic activity of MXene promoting rapid separation of photogenerated charges and resulting in well-separated electron and hole enriched sites. This study offers a new approach to enhance photocatalytic hydrogen evolution efficiency and paves the way for the future design of S-scheme heterojunctions. © 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.