Preparation Of Pd/Two-dimensional Nanosheet Composites For Photo-and Electrocatalysis Hydrogen Evolution

Nowadays,energy crisis and environmental contamination are serious issues and thus seeking for renewable and clean energy is an urgent task.Hydrogen?H₂?is predicted to be a promising secondary energy,with the advantages of high energy density and a useful by-product of water from combustion.As is known,nature abundantly stores hydrogen in the form of water.Therefore,hydrogen production by efficient water splitting has enormous capacity to fulfill the present and future demand of energy around the world in an eco-friendly manner.Two-dimensional?2D?nanomaterials and noble metal quantum dots are being widely investigated in the fields of water photolysis/electrolysis,owing to their uniqe structures and special properties.Among them,Pt noble metal shows the best catalytic performances,despite its scarcity and high costs that have hampered its utilization in larger scales.In this study,the new hybrids with the transitional metal Pd and 2D nanomaterials had been prepared,and their catalytic performances in photo/electro-induced water splitting were investigated.The main results of this thesis are as follows:?1?The Pd-rGO was prepared by in situ reduction of graphene-oxide and Pd were performed.Then the Pd-rGO was sonicated with the lithium intercalated and exfoliated MoS₂ nanosheets,to form a new MoS₂-Pd-rGO hybrid.Scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and X-ray diffraction?XRD?showed the uniform size and distribution of Pd nano dots on the surfaces of the rGO and MoS₂ sheets.Importantly,the hybrid showed improved photocatalytic activities,and the best performances could be achieved when the loading of MoS₂ was5wt%.In this case,a HER rate of 139.85?mol/h could be observed.?2?In situ reduction was also performed to prepare the new Pd-WS₂ hybrid.SEM,TEM and XRD tests showed the WS₂ remained clear layer structure,and abundant spherical shape Pd nanoparticles were deposited on the surface of the WS₂ sheets.Water electrolysis analysis demonstrated that the Pd-WS₂ hybrid showed significantly improved catalytic ability.The starting overpotential was 20 mV and the Tafel slop was 121.79 mV/dec.