A dual S-scheme TiO2@In2Se3@Ag3PO4 heterojunction for efficient photocatalytic CO2 reduction

Construction of TiO2/CuPc Heterojunctions for the Efficient Photocatalytic Reduction of CO2 with Water

Utilizing solar energy for photocatalytic CO2 reduction is an attractive research field because of its convenience, safety, and practicality. The selection of an appropriate photocatalyst is the key to achieve efficient CO2 reduction. Herein, we report the synthesis of TiO2/CuPc heterojunctions by compositing CuPc with TiO2 microspheres via a hydroxyl-induced self-assembly process. The experimental investigations demonstrated that the optimal TiO2/0.5CuPc photocatalyst exhibited a significantly enhanced CO2 photoreduction rate up to 32.4 μmol·g-1·h-1 under 300 W xenon lamp irradiation, which was 3.7 times that of the TiO2 microspheres alone. The results of photoelectrochemical experiments indicated that the construction of the heterojunctions by introducing CuPc effectively promoted the separation and transport of photogenerated carriers, thus enhancing the catalytic effect of the photocatalyst.

Rich oxygen vacancies in confined heterostructured TiO2@In2S3 hybrid for boosting solar-driven CO2 reduction

Solar energy driving CO2 reduction is a potential strategy that not only mitigates the greenhouse effect caused by high CO2 level in atmosphere, but also yields carbon chemicals/fuels at the same time. Herein, a facile way to design the heterogeneous TiO2@In2S3 hollow structures possessing robust light harvesting in both ultraviolet and visible regions is proposed and exhibits a higher generation rate of 25.35 and 1.24 μmol·g-1·h-1 for photocatalytic CO2 reduction to CO and CH4, respectively. The excellent photocatalytic catalytic performance comes from i) the confined heterostructured TiO2@In2S3 possesses a suitable band structure and a broadband-light absorbing capacity for CO2 photoreduction, ii) the rich interfaces between nanosized TiO2 and In2S3 on the shell can significantly reduce the diffusion length of carriers and enhance the utilization efficiency of photogenerated electron-hole pairs, and iii) enriched surface oxygen vacancies can provide more active sites for CO2 adsorption.

Modification engineering of TiO2-based nanoheterojunction photocatalysts

Titanium dioxide (TiO2)-based photocatalysts have gained increasing attention for their versatile applications in organic degradation, hydrogen production, air purification, and CO2 reduction. Various TiO2-based heterojunction structures, including type I, type II, Schottky junction, Z-scheme, and S-scheme, have been extensively studied. The current research frontier is centered on the engineering modifications of TiO2-based nanoheterojunction photocatalysts, such as defect engineering, morphological engineering, crystal phase/facet engineering, and multijunction engineering. These modifications enhance carrier transport, separation, and light absorption, thereby improving the photocatalytic performance. Remarkably, this aspect has been less addressed in existing reviews. This review aims to fill this gap by focusing on the engineering modifications of TiO2-based nanoheterojunction photocatalysts. We delve into specific topics like oxygen vacancies, n-p homojunctions, and double defects. The review also systematically discusses the applications of multidimensional heterojunctions and examines carrier transport pathways in heterophase/facet junctions and their interactions with heterojunctions. A comprehensive summary of multijunction systems, including multi-Schottky junctions, semiconductor-based heterojunction-attached Schottky junctions, and multisemiconductor-based heterojunctions, is presented. Lastly, we outline future perspectives in this promising research field. This paper will assist researchers in constructing more efficient TiO2-based nanoheterojunction photocatalysts.

S-scheme Cu3P/TiO2 heterojunction for outstanding photocatalytic water splitting

TiO2 photocatalysts are of great interest in the fields of environmental purification, new energy and so on, because of their non-toxicity, high stability, high redox ability and low cost. However, the photogenerated carriers are severely recombined, which limits the application of TiO2 photocatalysts. Herein, S-scheme Cu3P/TiO2 heterojunction composites were successfully synthesized by a simple and efficient microwave hydrothermal method, and the results show that the hydrogen production rate of Cu3P/TiO2 is 5.83 mmol∙g-1∙h-1 under simulated sunlight irradiation, which is 7.3 and 83.3 times higher than that of pure TiO2 and Cu3P, respectively. This excellent performance is derived from the internal electric field (IEF) and energy band bending generated by the S-scheme heterojunction formed between Cu3P and TiO2. The density functional theory (DFT) calculation indicates that the Cu3P possess smaller work function and more negative conduction band (CB) position than that of TiO2, which is very conducive to greatly improve the H+ reduction ability and hydrogen production performance. This work provides a new idea for the reveal of electron transfer paths and active sites in S-scheme heterojunctions and deepens the mechanism understanding.