Charge generation and separation are regarded as the major constraints limiting the photocatalytic activity of polymeric photocatalysts. Herein, two new linear polyarylether‐based polymers (PAE–CPs) with distinct linking patterns between their donor and acceptor motifs were tailor‐made to investigate the influence of different linking patterns on the charge generation and separation process. Theoretical and experimental results revealed that compared to the traditional single‐stranded linker, the double‐stranded linking pattern strengthens donor–acceptor interactions in PAE–CPs and generates a coplanar structure, facilitating charge generation and separation, and enabling red‐shifted light absorption. With these prominent advantages, the PAE–CP interlinked with a double‐stranded linker exhibits markedly enhanced photocatalytic activity compared to that of its single‐strand‐linked analogue. Such findings can facilitate the rational design and modification of organic semiconductors for charge‐induced reactions.
Covalent triazine‐based frameworks (CTFs) are typically produced by the salt‐melt polycondensation of aromatic nitriles in the presence of ZnCl2. In this reaction, molten ZnCl2 salt acts as both a solvent and Lewis acid catalyst. However, when cyclotrimerization takes place at temperatures above 300 °C, undesired carbonization occurs. In this study, an ionothermal synthesis method for CTF‐based photocatalysts was developed using a ternary NaCl‐KCl‐ZnCl2 eutectic salt (ES) mixture with a melting point of approximately 200 °C. This temperature is lower than the melting point of pure ZnCl2 (318 °C), thus providing milder salt‐melt conditions. These conditions facilitated the polycondensation process, while avoiding carbonization of the polymeric backbone. The resulting CTF‐ES200 exhibited enhanced optical and electronic properties, and displayed remarkable photocatalytic performance in the hydrogen evolution reaction.
To enhance the low hole mobility (∼40 cm V s) of InSe monolayer, a novel two-dimensional (2D) van der Waals heterostructure made of InSe and black phosphorus (BP) monolayers with high hole mobility (∼10 cm V s) has been constructed and its structural and electronic properties are investigated using first-principles calculations. We find that the InSe/BP heterostructure exhibits a direct band gap of 1.39 eV and type-II band alignment with electrons (holes) located in the InSe (BP) layer. The band offsets of InSe and BP are 0.78 eV for the conduction band minimum and 0.86 eV for the valence band maximum, respectively. Surprisingly, the hole mobility in the InSe/BP heterostructure exceeds 10 cm V s, which is one order of magnitude larger than the hole mobility of BP and three orders larger than that of the InSe monolayer. The electron mobility is also increased to 3 × 10 cm V s. The physical reason has been analyzed deeply, and a universal method is proposed to improve the carrier mobility of 2D materials by forming heterostructures with them and other 2D materials with complementary properties. The InSe/BP heterostructure can thus be widely used in nanoscale InSe-based field-effect transistors, photodetectors and photovoltaic devices due to its type-II band alignment and high carrier mobility.
The unexpected visible-light absorption, low recombination of electron−hole pairs, and high carrier mobility are found in a novel two-dimensional (2D) InSe/Zr 2 CO 2 van der Waals heterostructure for overall water splitting photocatalysis. The photocatalytic mechanism has been systematically investigated using first-principles calculations for the first time. We prove that the 2D InSe/Zr 2 CO 2 heterostructure is a robust and promising visible-light photocatalyst with several distinct advantages, as follows. It has a direct band gap of 1.81 eV, which is a more favorable band gap for visible-light photocatalysis. Its type-II band alignment directly leads to a significant electron−hole separation with electrons (holes) localized in the InSe (Zr 2 CO 2 ) monolayer. The indirect band gap of the InSe (Zr 2 CO 2 ) monolayer further suppresses the electron−hole recombination in it. Naturally, the recombination of the photogenerated electrons and holes is greatly suppressed in the InSe/Zr 2 CO 2 heterostructure, which improves the solar energy utilization effectively. Moreover, a large optical absorption coefficient (10 5 cm −1 ) has been confirmed in the 2D InSe/Zr 2 CO 2 heterostructure with the electron (hole) mobility reaching up to 10 4 (10 3 ) cm 2 V −1 s −1 , which is highly beneficial and desirable for enhancing its photocatalytic efficiency.
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