Green Synthesis And Electrocatalytic Performance Of Transition Mental Nitrides

With the gradual development of modern industry,today’s society is facing more and more serious energy problems and environmental pollution.In order to solve the existing problems,large-scale deployment of renewable energy generation is the first step.At present,the feasible way out is to store the remaining renewable energy for real-time supply,and hydrogen has been seen as an ideal alternative to traditional fossil energy because it is environmentally friendly and renewable.In order to better produce hydrogen from water electrolysis,the synthesis of electrocatalyst is particularly important.So far,precious metal-based catalysts are often used to accelerate the kinetics of electrochemical reactions.However,due to the high price and scarcity of precious metals,their commercial application in water electrolytic cells is easily limited.Therefore,in order to achieve green hydrogen production in the future,low-cost and efficient non-precious metal catalysts should be vigorously developed.In this paper,transition metal nitrides have been successfully prepared by nitriding with urea and applied to hydrogen evolution reaction（HER）,oxygen evolution reaction（OER）and urea oxidation reaction（UOR）,respectively,with the following main explorations:（1）In this chapter,we have prepared the synthesis of Ru-Ni₃N@NC by one-step hydrothermal method using tannic acid（TA）and urea as carbon and nitrogen sources by low-temperature nitrification.The experimental results show that the synthesized Ru-Ni₃N@NC has excellent hydrogen evolution performance in alkaline,neutral and alkaline seawater,and good electrocatalytic activity of oxygen evolution and urea hydrolysis.It is worth mentioning that the synthesized catalyst only needs a very small battery voltage to drive the dual-electrode electrolytic cell to produce hydrogen,and has long-term stability.（2）The work in the previous chapter has confirmed the effective strategy of transition metal nitride in the direction of electrocatalysis,and proved that the synthesized Ru-Ni₃N@NC electrocatalyst showed excellent electrocatalytic performance under alkaline,neutral and seawater conditions.In order to verify the universality of low temperature nitriding method to synthesize green catalyst,in this chapter,the Ni Mo Ox precursor was nitrided at different temperatures to synthesise two-dimensional graphene-like structure Ni-Mo N.The results show that the transition metal nitride of two-dimensional graphene structure has highly exposed active site and specific surface area,which makes Ni-Mo N show good hydrogen evolution reaction in 1 M KOH solution and urea hydrolysis performance in 1 M KOH with 0.33 M urea.Among them,it can drive high current density with small voltage under industrial conditions,and has good durability.（3）In this chapter,we continue to explore on the basis of metal nitrides and prepare a Ni-VN nanomaterial,which improves the electrochemical active site through the metal carrier interaction.And the synthesized materials have high catalytic activity and low production cost,and have broad application prospects in electrocatalytic hydrogen production and energy conversion.This work shows that transition metal nitride materials can achieve or even exceed the efficiency and durability of precious metal catalysts,which is expected to open a new path for the sustainable development of water electrolysis.