Photocatalytic Water Splitting Properties Of Lanthanide-Transition Metal Clusters

Due to the combination of different electronic structures of lanthanide and transition metal ions,lanthanide-transition metal clusters have unique optical,electrical,magnetic and catalytic properties.Here we mainly introduce the catalytic properties of lanthanide transition metal clusters,forming the lanthanide-transition cluster/semiconductor complexes by in-situ or post modified synthetic method.Because of the synergistic effect of the lanthanide-transition metal clusters,the lanthanide-transition metal cluster/semiconductor complexes exibited high efficiency of charge separation and transfer and high photocatalytic performance.This paper was around the title "Photocatalytic water splitting Properties of Lanthanide-Transition metal clusters",a series of high efficient catalysts of catalytic water splitting were prepared through combining 3d-4f cluster with inorganic semiconductor,and a variety of characterizations were made to prove the stability of the catalysts and explain catalytic reaction mechanism.The detailed findings are following:1.Synthesis and decoration of Ln2Ti4 lanthanide titanium-oxo clusters and the research of photocatalytic hydrogen performance.TiO2 is widely used in photocatalytic reactions,but its application is limited by the wide band gap.Therefore,it is of great significance to simulate the molecular catalysts similar to TiO2.Lanthanide ions have the effect of reducing the band gap of the titanium-oxo cluster and play an important role in synthesis and study of catalytic properties.We first used terpentanoic acid as ligand to synthesize a series of isomorphic Ln2Ti4(Ln=Eu,Gd,Tb,Ce)clusters.Among them,due to the appropriate reduction potential of Eu3+,Eu2Ti4 exihibed the highest photocatalytic hydrogen production performance under full light irradiation compared with other lanthanide clusters.In addition,in the process of in-situ synthesis of Eu2Ti4,CdS semiconductor was added as raw material to synthesize Eu2-xCdxTi4 cluster,which Eu3+was replaced by Cd2+.Thanks to the bond of Cd and S,Eu2-xCdxTi4 has higher hydrogen production performance than Eu2Ti4.In addition,the presence of reduced Eu2+was detected by in situ EPR characterization,revealing the photocatalytic reaction mechanism.2.Integration of Lanthanide-Transition Metal Clusters onto CdS Surfaces for Photocatalytic Hydrogen Evolution.The lanthanide-transition metal cluster Ln52Ni56(Ln=Eu,Gd,Nd,Pr)was introduced into CdS inorganic semiconductor materials,achieves efficient photon capture,charge separation and charge transfer efficiency,resulting in promoted photocatalytic performance.In the synthesis process,the excessive Cd2+replaced Ni2+in the cluster,forming the Ln52Ni56-xCdx/CdS composite.Photo-generated electrons can not only transfer to the LUMO orbital of the cluster,but also to the Eu3+to form the catalytic active site of Eu2+.The multi-path charge transfer enables Eu52Ni56-xCdx/CdS exhibit higher photocatalytic hydrogen production performance than other lanthanide homologues,reaching 25,353 mol h-1 g-1.The synergistic effect among the metals provides a reference for the synthesis of efficient photocatalytic semiconductor composites.3.Integration of Bio-Inspired Lanthanide-Transition Metal Cluster and PCN for Efficient Photocatalytic Overall Water Splitting..Based on the structure of photosynthsis system ?(PSII)of CaMn?Mn?2O5,we synthesized the similar structure of lanthanide-transition metal cluster LnCo?2Co?(Ln=Nd,Eu,Ce).The cluster was anchored on the photosensitive P-doped C3N4(PCN)to obtain a highly efficient photocatalytic overall water splitting.The stability of the catalyst was realized by the bond of Co ions in LnCo?2Co? cluster and P in PCN,shortening the distance of charge separation,transmission and transfer,thus promoting the photocatalytic performance.It shows a hydrogen production of 297.7 ?mol h-1 g-1 and an oxygen production of 148.9 ?mol h-1 g-1.By means of EXAFS and XPS,the possibility of bond effect between PCN and LnCo?2Co? and the stability of the catalyst were demonstrated.The mechanism of photocatalytic process was also studied by using transient absorption(TA)spectroscopy and DFT method.The formation of Ln-O-O-Co in the catalytic process shows the synergistic effect of the clusters,and plays an important role in photocatalytic water splitting.4.Lanthanide-Transition-Metal Clusters Ln36Co12:Effective Molecular Electrocatalysts for water oxidation.We prerared a series of Ln36M12(Ln=Eu,Gd,Dy;M=Co,Ni)clusters.They had sandwich structure with three hollow layers,the upper and lower layers are connected by 12 Ln3M cubane units,and the middle part is connected by Ln5 cubic units.The electrocatalytic oxygen performance of homogeneous catalyst under 0.5 M NaAc/HAc was studied.When pH=5.8,Eu36Co12 showed the optimal catalytic activity(TOF=1.5 s-1).A reasonable guess was made on the catalytic mechanism.The stability of clusters before and after catalysis in buffer solution was verified by DLS and EXAFS.