Design,Preparation And Photocatalytic Hydrogen Production Performance Of Non-Noble Metal Hydrogen-Producing Co-catalyst/UiO-66 Metal-Organic Frameworks Composites

At the moment when environmental problems and energy crises need to be solved urgently,the exploration of clean energy has great practical significance.Among them,photocatalytic hydrogen production that utilizes solar energy and photocatalytic materials for water splitting to prepare hydrogen is an ideal strategy.While exploring the deeper mechanism of photocatalytic reactions,the construction of efficient,inexpensive,and green photocatalytic materials has always been the core of this research field.Since the semiconductor material TiO2 has been proven to have the ability to decompose water for hydrogen production in 1972,the application of semiconductors to construct photocatalytic hydrogen production materials has received extensive attention.Among them,metal-organic framework materials(MOFs),constructed by coordination of metal ions or clusters with organic ligands have gradually developed into novel photocatalytic materials.The novel materials with such porous properties have the advantages of large specific surface area and controllable structures,and some MOFs with semiconductor properties have been widely applied in the fields of electrocatalysis and photocatalysis.However,in the photocatalytic hydrogen production,the performance of single semiconductor is poor.Generally,it is necessary to support noble metal as co-catalyst to enhance its catalytic performance.Considering its expensive price,attempts of replacing traditional noble metals with non-noble ones are conducive to promoting the application of photocatalytic hydrogen production research.In this paper,Zr-MOFs UiO-66 and its amino-functionalized UiO-66-NH2 were selected as the main materials.Hydrogen-producing co-catalysts that based on three non-noble metal elements(Mo,Cu,Ni)realized the effective loading with MOFs,with constructing three non-noble metal photocatalysts,[Mo3Si3]2-/UiO-66-NH2,Cu/UiO-66-NH2 and NiS2/UiO-66,by electrostatic adsorption,photo-deposition and hydrothermal synthesis strategies respectively.Photocatalytic experimental results indicate that the hydrogen production performance of three post-catalysts are greatly improved compared with bare MOFs.Subsequently,XRD,SEM,TEM,FT-IR,UV-vis,PL and electrochemical methods were used to characterize the morphology,structure and photoelectric properties of different samples.The mechanism of photocatalytic hydrogen production performance was described based on the characterization results.The main research contents are as follows:1.Compared to the conventional MoS2,thiomolybdate[Mo3S13]2-can expose more S active sites at the edge of molecule,as well as the negative charge characteristic.After acid treatment of UiO-66-NH2,more efficient charges transfer between MOFs and[Mo3S13]2-was achieved by electrostatic adsorption,then high catalytic activity of[Mo3S13]2-can be fully exerted.The results of photocatalytic experiments reveal that,under same loading amount(1.0 wt%),a 11-fold promotion in hydrogen production rate was observed with protonated sample compared to un-protonated one.Moreover,[M03S13]2-also exhibits better catalytic performance than the noble metal Pt.2.The Cu/UiO-66-NH2 non-noble metal catalyst was prepared by simple photo-deposition method.Due to the introduction of non-noble Cu,the separation of photo-generated electron-hole pair was promoted,while providing hydrogen evolution sites for UiO-66-NH2,which showed no hydrogen production activity.The Cu/UiO-66-NH2 series samples with different loading amount exhibited certain hydrogen production performance in the photocatalytic experiments.The optimum loading amount is 6.0 wt%,of which the hydrogen production rate is 40 μmol·9-1·h-1.3.The NiS2 nanoparticles were successfully loaded onto the surface of MOFs UiO-66 by hydrothermal method,sensitizing NiS2/UiO-66 complex with organic dye Erythrosine B.Under the excitation of visible light,photo-generated electrons can be efficiently transferred to the highly dispersed NiS2 nanoparticles on the UiO-66 surface and then catalyze the hydrogen production reaction.Simultaneously,the photocatalytic hydrogen production performance of pure UiO-66 under the same conditions is significantly improved with the photo-generated electrons,which are effectively separated with the holes.Under the optimal loading amount of 5.0 wt%,the hydrogen production rate of NiS2/UiO-66 is 4.8 times better than that of bare UiO-66.