A Methylthio‐Functionalized‐MOF Photocatalyst with High Performance for Visible‐Light‐Driven H₂ Evolution

Abstract

Recently, the emergence of photoactive metal-organic frameworks (MOFs) has given great prospects for their applications as photocatalytic materials in visible-light-driven hydrogen evolution. Herein, a highly photoactive visible-light-driven material for H evolution was prepared by introducing methylthio terephthalate into a MOF lattice via solvent-assisted ligand-exchange method. Accordingly, a first methylthio-functionalized porous MOF decorated with Pt co-catalyst for efficient photocatalytic H evolution was achieved, which exhibited a high quantum yield (8.90 %) at 420 nm by use sacrificial triethanolamine. This hybrid material exhibited perfect H production rate as high as 3814.0 μmol g h , which even is one order of magnitude higher than that of the state-of-the-art Pt/MOF photocatalyst derived from aminoterephthalate.

Highly Stable Phosphonate‐Based MOFs with Engineered Bandgaps for Efficient Photocatalytic Hydrogen Production

“…[ 5,6 ] The metallic blocks mainly correspond to di/trivalent cations of 3d transition metals (e.g., Fe, Zn, Ni) and 3p metals, [ 5–9 ] among which Ti is an attractive candidate because of its relatively low cost, redox activity, and photocatalytic properties. [ 10–16 ] Incorporating Ti‐oxo clusters delivers the semiconductor behavior of the MOFs with decent solar energy conversion efficiency, due to the facilitated electron transfer from the photoexcited organic linkers to the Ti‐oxo clusters (i.e., linker‐to‐cluster charge transfer, termed as LCCT). [ 13–18 ] Particularly, bandgaps in the MOFs can be adjusted via modifying the organic linkers (e.g., introducing new functional groups), which can open up new possibilities to control the electronic structures/states of photocatalysts at the molecular level.…”

“…[ 10–16 ] Incorporating Ti‐oxo clusters delivers the semiconductor behavior of the MOFs with decent solar energy conversion efficiency, due to the facilitated electron transfer from the photoexcited organic linkers to the Ti‐oxo clusters (i.e., linker‐to‐cluster charge transfer, termed as LCCT). [ 13–18 ] Particularly, bandgaps in the MOFs can be adjusted via modifying the organic linkers (e.g., introducing new functional groups), which can open up new possibilities to control the electronic structures/states of photocatalysts at the molecular level. [ 13–20 ] For instance, replacing a terephthalate linker in MIL‐125 (a MOF constructed by terephthalate linker and Ti‐oxo clusters) with the 2‐aminoterephthalate linker could lead to a significantly decreased bandgap of MIL‐125‐NH 2 .…”

“…[ 13–18 ] Particularly, bandgaps in the MOFs can be adjusted via modifying the organic linkers (e.g., introducing new functional groups), which can open up new possibilities to control the electronic structures/states of photocatalysts at the molecular level. [ 13–20 ] For instance, replacing a terephthalate linker in MIL‐125 (a MOF constructed by terephthalate linker and Ti‐oxo clusters) with the 2‐aminoterephthalate linker could lead to a significantly decreased bandgap of MIL‐125‐NH 2 . [ 13 ] Furthermore, judicious control over the facets of MIL‐125‐NH 2 nanocrystals could further improve photocatalytic H 2 production activity as a result of increased percentage of exposed metal clusters.…”

“…[ 17,19 ] This effect is similar to previous carboxylate‐based MOFs with electron‐donating functional groups. [ 15,17,19,37 ] The much less sensitivity of the CB energy level is due to the fact that the CB character mainly relates to the Ti 3d electrons or the orbitals delocalized over the whole organophosphonic linker. [ 17,37,45,46 ] Additionally, TiPNW exhibits a smaller slope than that of TiO 2 in the Mott–Schottky spectra, revealing a higher electron density and a faster charge transfer.…”

“…The electrochemical impedance spectroscopy (EIS) measurement manifests a much decreased arc diameter on TiPNW (Figure S17, Supporting Information), which can be related to the increased interfacial electron mobility. [ 15,48 ] After normalizing hydrogen production rate by specific surface area (Figure S18, Supporting Information), TiPNW shows a normalized rate of 0.394 µmol h −1 m −2 g −1 , still outperforming TiPNP (0.075 µmol h −1 m −2 g −1 ), though TiPNP has a larger surface area. This reveals that the photocatalytic activity is not simply related to the surface area but also intimately associated with the nanostructure.…”