Study On Cobalt And Nickel-Based Cocatalysts To Enhance Photo (Electro) Catalytic Activity For Hydrogen And Oxygen Evolution

With the increasing global energy consumption,the shortage of fossil energy and the pollution caused by its combustion have attracted more and more attention.Hydrogen energy is considered to be a promising clean energy and may become an alternative fuel to non-renewable fossil fuels in the future.Currently,the commonly used methods of producing hydrogen in industrial production require huge energy consumption..If hydrogen is produced by photocatalytic decomposition of water,it can directly convert solar energy into chemical energy,which is one of the most ideal ways to produce clean and renewable hydrogen energy.To enhance the photocatalytic activity of semiconductor catalysts,it is a simple and feasible strategy to use cocatalysts to modify them This thesis focuses on the design and synthesis of cobalt-and nickelbased non-noble metal cocatalysts,as well as their coupling with different semiconductor catalysts,and explores their performance in the field of photocatalytic/p ho toe lec trocatalytic hydrogen evolution and oxygen evolution.The following are the specific research contents:1.Nickel cobalt phosphide(NiCoP)nanoparticles were synthesized as a cocatalyst for photocatalytic formic acid dehydrogenation.NiCoP was in situ grown on cadmium sulfide(CdS)nanorods by hydrothermal reaction and high temperature calcination phosphating.The experimental results confirm that the modification of NiCoP cocatalyst on the surface of CdS nanorods can enhance their photocatalytic activity for hydrogen evolution which is about 63 times higher than that of blank CdS nanorods under the same conditions.And in this reaction,the catalytic performance of NiCoP is better than those of noble metals such as platinum,gold,and palladium.Under the monochromatic illumination at 420 nm,the apparent quantum efficiency of the system for hydrogen production can reach 45.5%.Further experiments and characterizations show that NiCoP could promote the charge separation and electron transfer of CdS,thereby enhancing the activity of photocatalytic hydrogen evolution.2.A bismuth vanadate(BiVO4)composite photoanode co-modified with molecular cobaloxime cocatalyst and FeOOH nanolayers was designed and constructed and used for photoelectrocata lytic oxygen evolution reaction of water decomposition.This photoanode is prepared by depositing FeOOH layers on the surface of BiVO4 by using a chemical bath method at room temperature,and then drop-coating the molecular cobaloxime solution on the surface of it Under simulated sunlight irradiation,the photocurrent density at the water oxidation potential is 5.1 mA cm’2,and the surface hole injection efficiency can reach 80%.In addition,the stability of the modified photoanode has also been significantly improved.