Strategy to enhance photocatalytic performance of heterojunctional composite by dimensionality modulating: Insights into the scheme in interfacial charge migration and mass transfer

As a structural parameter, dimensionality is a key factor but was usually ignored in the design of novel heterojunction architectures in achieving their photocatalytic performances. Hence in this work, we obtained onedimensional titanate nanotubes (TNTs), two-dimensional titanate nanoflakes (TNF) and three-dimensional titanate nanospheres (TNS) with facile treatments of TiO2 by NaOH, and combined them with twodimensional sulfur-doped g-C3N4 nanoflakes (SCN), respectively, through magnetic and ultrasonic mixing in isopropanol. Their performances in photodegradation of tetracycline hydrochloride (TC-HCl) under simulated solar light irradiation exhibit significant superiorities of the composites over their individuals, while the photodegradation rates obtained on composites indicate a vital importance of their interfacial intimacy in heterojunctions. The photoactivity of TNF/SCN with a suitable face-face contact represents a rate constant as high as 0.1642 min-1, which is 1.58 and 2.65 times of what on TNS/SCN (0.1036 min-1) and TNTs/SCN (0.0619 min-1), respectively. Careful characterization and theoretical calculation indicated dense junction between different titanates and SCN via van der Waals integration. In these dense heterojunctions, an internal electronic field of about 0.75 V can automatically be formed between titanates and SCN during the assimilation of their Femi level by electronic coupling, to realize migration and separation of photogenerated carriers through an S-scheme. Moreover, the interfacial intimacy benefited from suitable dimensionality of titanates can promote the efficiency of S-scheme to acquire a prolonged lifetime of center dot OH and center dot O2-, and intraparticle transfer of TC-HCl towards their degradation. This work provides new insights into the rational design of heterostructures based on dimensional modulation on the interfacial affinity for accelerating the transfer of interfacial charge and the intraparticle transfer of contaminants.

Automated summary

By modulating the dimensionality of materials, this research creates dense dehydration effects in heterojunctions, promoting the migration and separation of photogenerated carriers and effectively improving the efficiency of photocatalytic degradation.