NH2-MIL-125(Ti) with transient metal centers via novel electron transfer routes for enhancing photocatalytic NO removal and H2 evolution

Abstract

The bifunctional photocatalyst Yb–NH₂-MIL-125(Ti) synthesized using a simple and convenient method enhanced photocatalytic NO removal and hydrogen production simultaneously, in which the formation of Yb species transient centers anchored on NH₂-MIL-125(Ti) accelerated the transfer and separation rate of charge carriers. The NO removal rate of the optimal sample Yb-NM-6 was 66.3% (the original NH₂-MIL-125(Ti) was only 28.1%), and the hydrogen production was 1883.7993 μmol g⁻¹ (the original NH₂-MIL-125(Ti) had almost no effect). A series of comparative experiments, in particular cyclic voltammogram tests, showed that the transient Yb^II/III centers were obtained through a non-traditional ligand to linker metal charge transfer (LLMCT) pathway, which was very different from the traditional ligand metal charge transfer (LMCT) pathway, so as to form a novel charge transfer channel to improve photocatalytic performance. This work details a feasible avenue by which to obtain a novel LLMCT pathway through introducing various metal ions anchored on metal–organic frameworks as efficient transient centers to further improve photocatalytic performance.