Preparation Of Transition Metal Catalysts And Their Properties Of Electrolytic Water

With entering the 21st century,the development of new energy sources to replace fossil fuels has become increasingly urgent.Hydrogen energy,with its ultra-high energy density,abundant sources and pollution-free properties,becomes the most promising renewable energy alternative to traditional fossil fuels.The use of high efficiency catalyst to promote water decomposition in electrolysis process has become a feasible approach in the future.Currently,the best catalysts for hydrogen evolution reaction?HER?are the Pt-based catalysts,and the best catalysts for oxygen evolution reaction?OER?is the Ru-based or Ir-based catalysts.These catalysts are difficult to meet market demand due to high price and rare storage in the crust,which also limits the large-scale utilization of hydrogen energy.Cobalt-based catalysts are widely recognized for their advantages such as many types of dopable atoms,good long-term stability,bifunctional catalysis,and low price.In this paper,it is proposed that Ru and P be doped into the cobalt tetroxide?Co₃O₄?nanoarray for modification to achieve the purpose of improving catalyst performance.The specific research contents are as follows:First,based on the nickel foam?NF?as the substrate,the four catalysts required for electrolyzed water were synthesized by hydrothermal method and low temperature annealing:cobalt tetroxide/nickel foam?Co₃O₄/NF?,cobalt ruthenium oxide/nickel foam?CoRuO/NF?,cobalt phosphorus oxide/nickel foam?CoPO/NF?and cobalt ruthenium phosphorus oxide/nickel foam?CoRuPO/NF?.Scanning electron microscope,X-ray diffractometer,X-ray photoelectron spectroscopy and other test methods were used to characterize the influence of Ru and P doping on the morphology and structure of Co₃O₄/NF.The results showed that the morphology is basically unchanged after Ru and P doping on Co₃O₄/NF,and a small amount of Ru doping can cause a certain displacement of the binding energy of Co and O elements in the samples,resulting in a change in the electron density,thereby causing a change in catalytic performance.Secondly,we studied the catalytic activity of CoRuPO/NF catalyst in alkaline ultrapure aqueous solution,alkaline simulated seawater solution and alkaline real seawater solution.In 1 M KOH electrolyte,the overpotential of CoRuPO/NF for HER is only 54 mV at 10 mA cm^-2,and the overpotential for OER is only 340 mV at 50 mA cm^-2,which indicates the CoRuPO/NF has outstanding HER and OER activity.At the same time,there was no significant attenuation of the current in the 10 h current-time test.The displacement of linear sweep voltammetry?LSV?curves was small after 1000CV cycles,indicating that the catalyst has excellent stability.In alkaline simulated seawater solution and alkaline real seawater solution,the overpotential of CoRuPO/NF for HER are 59 mV and 65 mV at 10 mA cm^-2,respectively.Also,the overpotential for OER are 426 mV and 442 mV at 50 mA cm^-2,respectively.This results demonstrate that CoRuPO/NF have good capacity for HER and OER in alkaline seawater solution.In addition,the current did not change significantly under long-term testing at constant voltage.The lower overpotential and better stability indicate that CoRuPO/NF catalyst can be used as a potential catalyst for directly decomposing seawater.This work shows that Ru and P dopants can improve the intrinsic activity of the active site on the catalysts and improve the performance of the catalysts,providing an effective strategy for the future preparation of high atom utilization transition metal supported foam nickel catalyst performance.