Highly Water-Stable and Efficient Hydrogen-Producing Heterostructure Synthesized from Mn_0.5Cd_0.5S and a Zeolitic Imidazolate Framework ZIF-8 via Ligand and Cation Exchange

Abstract

Developing highly water-stable zeolitic imidazolate frameworks (ZIFs) for visible-light-driven photocatalytic hydrolysis is important and challenging. Herein, the Type II heterojunction catalyst Mn0.5Cd0.5S@ZIF-8 and its derivatives (including MCS@ZIF-8-Mn, MCS@ZIF-8-Br, and MCS@ZIF-8-MB) were successfully constructed using a facile strategy. Through dual postsynthetic ligand and cation exchange (PSE) treatments of Mn(Ac)2·4H2O and 4-bromo-1H-imidazole for ZIF-8, the hydrogen production efficiency of the MCS@ZIF-8-MB heterojunction catalyst can reach 5.450 mmol·g–1·h–1 and remain at 97.11% after 9 h of the stability test. Construction of heterojunctions can effectively improve the hydrogen production performance of Mn0.5Cd0.5S while maintaining excellent water stability. X-ray photoelectron spectroscopy results show that upon successful construction of the MCS@ZIF-8-MB heterojunction an interface forms between the surface of MCS and ZIF-8-MB, effectively weakening the photocorrosion of MCS. Density functional theory calculations also indicate that the induction of Mn can increase the electronic states of p and d orbitals near the Fermi level of ZIF-8, suggesting that Mn(II) attracts more electrons than Zn(II). This provides more powerful theoretical evidence for the electron cloud shift from the electron donor S2– to Mn2+.

Quantum Dot/ZIF-67/ZIF-8 Heterostructure for Efficient Photocatalytic Hydrogen Production

“…However, this change is small, indicating an indirect effect. Two obvious peaks on the high-resolution spectrum (Figure d) of Zn 2p in the sample QDs@ZIF-67/ZIF-8 are located at 1045.28 and 1022.18 eV, attributed to Zn 2p 1/2 and Zn 2p 3/2 , respectively, which shows positive deviation than those reported in the literature. − After careful inspection of the spectrum of Co 2p (Figure e), it was found that two other companion peaks appeared in addition to the two characteristic peaks, Co 2p 1/2 and Co 2p 3/2 . Two distinct peaks in the sample QDs@ZIF-67/ZIF-8 are located at 797.08 and 781.08 eV, while the corresponding two peaks in sample QDs@ZIF-67 are located at 796.78 and 781.18 eV.…”

Molten Alkali-Assisted Formation of Silicate Gels and Its Application for Preparing Zeolites

“…Zeolite is widely used in pollutant control, petrochemistry, water purification, gas purification, and other fields because of its excellent catalytic ability, cation exchange ability, and adsorption ability [ 1 , 2 , 3 , 4 ]. The main chemical components of fly ash are silica and alumina, which are similar to zeolite [ 5 , 6 ].…”