New Insights into Defect-Mediated Heterostructures for Photoelectrochemical Water Splitting

Understanding the interfacial electronic structures of heterojunctions, a challenging undertaking, is extremely important to the design of photoelectrodes for efficient water splitting. The heterostructured interfaces in terms of crystal defects at the atomic-level exemplified by TiO2/BiVO4 are studied. Results from both experimental observations and theoretical calculations clearly confirm the spontaneous formation of defective interfaces in the heterostructures. TiO2/BiVO4 junction with engineered interfacial defects can efficiently increase the carrier density and extend the lifetime of electrons. The inherent phenomenon of defective electronic structures in different heterostructures creates a significant impact on their photoelectrochemical performance. The synergetic effect between defect-mediated mechanism and organic quantum dots sensitization yields significantly increased photoconversion efficiency, which is even superior to that of common metal sulfide sensitized ones. This result demonstrates an approach worthy for the design and fabrication of defect-mediated heterostructures for water splitting, without utilizing harmful metal sulfides. Moreover, new insights into the influence of intrinsic defects on the interfacial charge transfer process between two different semiconductors for energy-related applications have also been provided.