Cerium versus zirconium UiO66 metal–organic frameworks coupled with CdS for H₂ evolution under visible light

Abstract

Metal-organic frameworks (MOFs) as a highly porous photocatalyst have received an increasing attention. Among them, much work has focused on UiO66, due to its high stability in water. In this...

Substituted Ti(IV) in Ce-UiO-66-NH2 Metal–Organic Frameworks Increases H2 and O2 Evolution under Visible Light

“…Physical Parameters for (Ti/Ce) x -MOF and yCdS/(Ti/Ce) 1.5 -MOF a x 2θ (degree) decreased A sp and V mp on CdS loading, respectively. 15 Note that Shi and co-workers have also reported a hysteresis loop of N 2 adsorption for CdS/UiO-66-(SH 2 ). They concluded that CdS particles are present, either on the external surface of MOF or in the cavities of MOF.…”

“…Meanwhile, the A sp , V mp , and V tp decreased with x , respectively (Table S2), the trends being in accordance with those measured for CdS-free (Ti/Ce) x -MOF (Table ). On the other hand, it is also possible that CdS particles fill up the micropores of Ti/Ce-MOF so that the solid has a decreased A sp and V mp on CdS loading, respectively . Note that Shi and co-workers have also reported a hysteresis loop of N 2 adsorption for CdS/UiO-66-(SH 2 ).…”

“…For a dual metal MOF, the narrowed band gap is due to the unoccupied Ti 3d and Ce 4d orbitals being located below the unoccupied Zr 4d orbitals, respectively. 14 Furthermore, for the photocatalytic evolution of H 2 under similar conditions, the UiO-66-based MOFs exhibit different activities of Ce-UiO-66-NH 2 > Zr-UiO-66-NH 2 > Ce-UiO-66 > Zr-UiO-66, 15 and Co/Zr-UiO-66-NH 2 > Ni/Zr-UiO-66-NH 2 > Fe/Zr-UiO-66-NH 2 > Zr-UiO-66-NH 2 . 16 In all cases, however, the production of H 2 is efficient only in the presence of sacrificial reagents (methanol, triethanolamine, triethylamine, and Na 2 S/Na 2 SO 3 ) and/or in the presence of co-catalysts (CdS, MoS 2 , H 3 PW 12 O 40 , and noble metals).…”

“…For a dual metal MOF, the narrowed band gap is due to the unoccupied Ti 3d and Ce 4d orbitals being located below the unoccupied Zr 4d orbitals, respectively . Furthermore, for the photocatalytic evolution of H 2 under similar conditions, the UiO-66-based MOFs exhibit different activities of Ce-UiO-66-NH 2 > Zr-UiO-66-NH 2 > Ce-UiO-66 > Zr-UiO-66, and Co/Zr-UiO-66-NH 2 > Ni/Zr-UiO-66-NH 2 > Fe/Zr-UiO-66-NH 2 > Zr-UiO-66-NH 2 …”

Adjusting the match-degree between electron library and surface-active sites and forming surface polarization in MOF-based photo-cocatalysts for accelerating electron transfer

“…This can be explained by the substitution of a small portion of Co by Ni leading to the disruption and redistribution of the electron cloud equilibrium in the catalytic system, resulting in a polarization phenomenon that facilitates the migration of charge carriers in the system. 51 When the loading amount of the cocatalyst reaches 7%, the synergistic effect between the two catalytic components is optimal, because the suitable loading amount of the cocatalyst is beneficial to improve the photo-response of the system. As illustrated in Fig.…”