Fe₂O₃/TiO₂/WO₃/Ti₃C₂T_x heterojunction composite material for efficient photoelectrochemical water splitting

Efficient photocatalytic performance plays a pivotal role in tackling our present energy challenges. A well-designed arrangement of nanoscale semiconductors and metallic components within multi-heterojunction photocatalysts can establish rapid transport pathways, enhancing the separation and migration of charge carriers. This approach offers a viable strategy towards achieving optimal photocatalytic efficiency. Herein, the glancing angle deposition technique (GLAD) technology of electron beam evaporation and spin-coating method were used to construct Fe₂O₃/TiO₂/WO₃/Ti₃C₂T_x quaternary composite materials with serial heterojunctions. Photocatalytic activity was assessed through photoelectrochemical tests, revealing that the Fe₂O₃/TiO₂/WO₃/Ti₃C₂T_x composite material outperformed its counterparts under visible-light irradiation. Notably, it achieved the highest photocurrent response, with a maximum photocurrent density of 1.09 mA/cm². This represented a substantial improvement, surpassing Fe₂O₃, Fe₂O₃/TiO₂, and Fe₂O₃/TiO₂/WO₃ photocatalysts by factors of 36, 2.8 and 1.25, respectively. This remarkable enhancement can be attributed to the formation of three heterojunctions in series, creating multiple pathways for efficient charge transfer and separation during the photocatalytic process. Furthermore, we proposed a photocatalytic mechanism for quaternary heterojunctions based on band structure analysis.