JMCA: A two-dimensional semiconductor zinc-based coordination polymer with excellent photocatalytic hydrogen production performance [Article Information] First author: Xiang Shuo, Arshad Khan Corresponding author: Wang Xin*, Weng Qunhong* Unit: Hunan University, Taiyuan Universit

JMCA: A two-dimensional semiconductor zinc-based coordination polymer with excellent photocatalytic hydrogen production performance

[Article information]

first author: Xiang Shuo, Arshad Khan

Corresponding author: Wang Xin*, Weng Qunhong*

Unit: Hunan University , Taiyuan University of Technology , Xiamen University

[Research background]

Hydrogen As a zero-pollution energy with high energy density, it has attracted more and more attention, and solar-powered photocatalytic hydrogen production is one of the ideal ways to produce green hydrogen. Many semiconductor photocatalysts have been widely studied for water dissecting hydrogen, but most semiconductor photocatalysts have low mobility and utilization of photogenerated carriers, resulting in lower overall photocatalytic activity. Metal-organic coordination materials have the advantages of adjustable band gaps and controllable catalytic sites due to their diverse metal ions and organic ligands, which are of great research value. However, its block material efficiency is still limited, and designing a low-dimensional structure provides a feasible way to improve its photocatalytic activity.

This work reported that the construction of a new Zn(II) and a two-dimensional coordination polymer of nitrile-containing double-arm trippyridine at the liquid-liquid interface, the optical band gap was reduced to 1.70 eV, and showed high hydrogen production activities of 3.10 mmol h-1 g-1 (N2 saturation) and 11.84 mmol g-1 h-1 (CO2 saturation) in the liquid-liquid interface, providing a new idea for the design of excellent photocatalyst based on 2D CONASH structure and band gap engineering.

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[Article Introduction]

Recently, Professor Weng Qunhong from Hunan University cooperated with Professor Wang Xin of Taiyuan University of Technology to publish an article titled "Photocatalytic hydrogen evolution from water based on Zn-terpyridine 2D coordination nanosheets" in the internationally renowned journal Journal of Materials Chemistry A.

Figure 1. Schematic diagram of photocatalytic hydrogen production of Zn-Typ coordination polymer (Zn-Typ CONASH), with an optical band gap of 1.70 eV, and the photocatalytic hydrogen production efficiency under CO2 saturation conditions was 11.84 mmol g-1 h-1.

[Big points of this article]

Key points 1: Construct a 2D structure through hydrogen bonding between Zn-Tpy chains

In this work, the author used a bottom-up method to form a one-dimensional Zn-Tpy chain through the liquid-liquid interface reaction, and formed a one-dimensional Zn-Tpy chain through the coordination between nitrile-group-containing double-arm trippyridine ligand and Zn(II) through the coordination between nitrile groups, and further self-assembled through hydrogen bonding between CN and H between chains, forming a new type of Zn-Tpy two-dimensional coordination nanosheet (CONASH). The authors characterized the structure of Zn-Tpy CONASH through FTIR, XPS, XRD spectroscopy and other methods in detail. Small angle XRD characterization combined with theoretical simulation also further demonstrates that the proposed two-dimensional Zn-Tpy CONASH structural model is reasonable.

Figure 2. Synthesis of Zn-Typ CONASH using liquid-liquid interface reaction and its morphological characterization.

Key points 2: Semiconductor bandgap feature

In this work, the Tpy band gap was measured to be 2.58 eV, and after coordination with Zn, the resulting Zn-Tpy CONASH band gap dropped to 1.70 eV, meaning that the material can absorb light at wavelengths within 730nm. This covers almost the entire visible band, so sunlight can be used to a large extent. It is also shown that the construction of metal coordination polymers as a simple and effective method for bandgap regulation may play a unique role in the design and construction of semiconductor nanomaterials.

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Key points three: High-efficiency photocatalytic hydrogen production performance

Through photocatalytic hydrogen production experiments, it can be found that in the N2 environment, the photocatalytic hydrogen production efficiency of Zn-Tpy is 3.10 mmol g-1 h-1, which is about 29 times that of the original Tpy (0.107 mmol g-1 h-1). It is shown that through metal coordination, the band gap can be adjusted and the photocatalytic hydrogen production performance of the material can be optimized.Theoretical calculations show that a strong intramolecular electrostatic field is formed after the formation of the Zn2 (μ-O2SO2)2 structure, which is crucial to improving the dispersion efficiency of photogenerated electron-hole pairs and improving the photocatalytic efficiency of Zn-Tpy-CONASH. When using a CO2 saturated solution, its hydrogen production efficiency is increased to 11.84 mmol g-1 h-1. Experiments show that some intermediates produced during photocatalytic reduction of CO2 may play an important role in promoting the photocatalytic hydrogen production activity of the sample, including but not limited to HCOOH.

Figure 3. (a) simulated electrostatic potential (ESP) and (b) differential charge density (DED) of Zn-Tpy and Tpy.

[Article link]

Photocatalytic hydrogen evolution from water based on Zn-terpyridine 2D coordination nanosheets

https://doi.org/10.1039/D2TA05114A

【 Corresponding Author Introduction】

Profile of Professor Weng Qunhong : Currently a professor and doctoral supervisor at Hunan University, he has long been committed to the design and innovative application of boron nitride functional ceramic materials and new lightweight semiconductor materials. Many work has been published in Adv. Mater., J. Am. Chem. Soc., Adv. Energy Mater., Adv. Funct. Mater., ACS Nano and other authoritative journals of . The article has been cited more than 5,000 times. The work has been supported by projects such as the National High-level Talent Project, the National Natural Science Foundation of , and the German Humboldt Scholars Foundation.

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Introduction to Dr. Wang Xin : Currently working at Taiyuan University of Technology, mainly engaged in the controllable synthesis and performance of

​(1) Research on the controllable synthesis and performance of nanoparticles;

​(2) Interaction between nanomaterials and biological macromolecules

​(3) Research on the surface modification and biocompatibility of medical metal materials.

​Multiple work has been published in Langmuir., Phys. Chem. Chem. Phys., J. Mater. Sci-Mater. M., Inorg. Chem., etc. journals. It has received support from Taiyuan University of Technology Talent Introduction Fund, Taiyuan University of Technology Youth Fund, Shanxi Provincial Youth Fund and other projects.

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[Recruitment of the research group]

Research group has long-term recruitment of teacher postdoctoral with backgrounds in materials/chemistry/biology, etc.! Welcome to contact the master's degree students and doctoral students applying for the assessment system!