Synthesis And Electrocatalytic Performance Of Iridium-based Nanomaterials

The excellent electrocatalytic properties of iridium-based nanomaterials have attracted the attention.In this dissertation,a series of Ir-based alloy nanomaterials have been prepared and their electro-catalytic activities for hydrogen oxidation reaction(HOR)or oxygen evolution reaction(OER)were discussed.The specific research contents are summarized as follows:1.Here we controllably synthesized IrCu nanoparticles with varying particle sizes and carbon supported iridium nanoparticles(Ir/C)and studied their OER activities under acidic conditions.The sizes of the nanoparticles can be adjusted by changing the ratio of the Ir/Cu precursor,the reaction temperature,and the amount of the reducing agent.Surfactants also have a large effect on the morphology of the nanoparticles.It was found that the IrCu-12/C exhibited superior OER activity compared to IrCu-15/C,IrCu-9/C,IrCu-6/C and Ir/C.Only a overpotential of 292 mV is required to obtain a current density of 10 mA cm-2 in 0.1 M HCIO4.Therefore,this study shows that the alloy effect and particle size are both key factors affecting the electro-catalytic activity.2.Herein,a novel and efficient IrCuNi concave nanocubes(IrCuNi CNCs)catalyst for OER was synthesized by a simple liquid phase method.The carbon supported IrCuNi concave nanocubes(IrCuNi CNCs/C)catalyst showed high electrocatalytic activity and excellent durability for OER in acidic media.It is worth noting that the overpotential of IrCuNi CNCs/C is only 273mV for a current density of 10 mA cm-2 in 0.01M HClO4 and Tafel slope is just 41 mV dec-1,which is better than Ir/C catalyst.In the stability test,IrCuNi CNCs/C still had a low overpotential,and electrocatalytic activity lost only 9.12%.It demonstrates that the outstanding catalytic performance is beneficial from well-defined multimetallic concave nanostructures and alloy effect.3.We successfully prepared hollow IrCuCo nanospheres and studied their HOR activities under alkaline conditions.The hollow structure is beneficial to increase the number of active sites and promote mass transfer.The hollow structure is formed due to the kirkendall effect and lattice mismatch between Co and Ir during the growth process.The introduction of Co can also change the surface electronic state,which adjusted the HBE of IrCuCo/C.IrCuCo/C exhibits superb activity in 0.1 M KOH and the exchange current density is 0.69 mA cm-2 and 2.3 times higher than that of Ir/C.The experimental results show that the hollow structure and alloy effect of IrCuCo/C are important for the HOR activities.