Insights into conduction band flexibility induced by spin polarization in titanium-based metal-organic frameworks for photocatalytic water splitting and pollutants degradation

Junjie Xu; Lun Lu; Chao Zhu; Qile Fang; Renlan Liu; Da Wang; Zhiqiao He; Shuang Song; Yi Shen

doi:10.1016/j.jcis.2022.10.015

Insights into conduction band flexibility induced by spin polarization in titanium-based metal-organic frameworks for photocatalytic water splitting and pollutants degradation

J Colloid Interface Sci. 2023 Jan 15;630(Pt A):430-442. doi: 10.1016/j.jcis.2022.10.015. Epub 2022 Oct 8.

Authors

Junjie Xu¹, Lun Lu², Chao Zhu¹, Qile Fang³, Renlan Liu⁴, Da Wang¹, Zhiqiao He¹, Shuang Song¹, Yi Shen⁵

Affiliations

¹ Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310032, China.
² State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510655, China.
³ Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai 519087, China.
⁴ College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China.
⁵ Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310032, China. Electronic address: shenyi@zjut.edu.cn.

PMID: 36265344
DOI: 10.1016/j.jcis.2022.10.015

Abstract

Solar energy is becoming the most promising option to mitigate the energy crisis in the future and can be applied in renewable and economical technologies such as water splitting and pollutants degradation. The promotion of the electronic energetic level is considered an efficient method to enhance the photocatalytic performance of semiconductor materials for solar energy conversion. The highly energetic electrons exhibit a remarkable reduction ability by virtue of the electronic spin polarization, which is associated with the conduction band (CB) position. Thus, the regulation of the CB position due to the redistribution of electrons by means of defect engineering presents potential. Here, a series of titanium-based metal-organic frameworks (Ti-based MOFs) named MIL-125-m% containing different extents of defects are reported to enable photocatalytic activity under simulated sunlight and visible light illumination for remarkably enhanced photocatalytic hydrogen evolution and pollutant degradation. The experimental results illustrated that MIL-125-5 % exhibited a superior photocatalytic hydrogen evolution rate (16507.27 μmol·g^-1·h^-1), much higher than that of MIL-125-0 % (1.444 μmol·g^-1·h^-1). The excellent photocatalytic performance was attributed to upshift of d-band center, which strengthened the adsorption of H*, facilitating the H₂ evolution reaction. In addition, the degradation rate of MIL-125-5 % was up to twice the original rate, for the highly energetic electrons induced by the CB flexibility alleviated the photoinduced electron recombination in defective MIL-125. The strategy of defect engineering provides a new path to control the flexibility of the CB position by electronic spin polarization on adjustable metal-organic frameworks (MOFs), and the photocatalytic effect is changed accordingly.

Keywords: Conduction band flexibility; Electronic redistribution; Metal-organic frameworks; Photocatalytic pollutants degradation; Spin polarization.