Synthesis Of Cobalt Elements Based Nanomaterials And Application Of Electrocatalytic Nitrogen Reduction Reaction

Ammonia is an important industrial raw material,which is widely used in various fields.Hubber–Bosch process,as the mainstream ammonia synthesis process at present,consumes a lot of energy and also causes a lot of greenhouse gas emissions.Electrocatalytic nitrogen reduction reaction（NRR）,as an environmentally friendly method for N₂ fixation,has attracted extensive attention from international researchers.Activation of N₂ molecules is a major challenge for current research because of its inert nature.In addition,the Faraday efficiency（FE）of electrocatalytic NRR is limited due to the competition of hydrogen evolution reaction（HER）in water system.Therefore,the development of electrocatalysts with high catalytic activity and NRR selectivity has become the focus of electrocatalytic NRR research.Among these catalysts,precious metal catalysts are particularly outstanding,but due to their low reserves and high prices,it is difficult to be applied in large–scale industrial production.Therefore,in recent years,non–noble metal catalysts research occupies the main position.Iron group elements possess the characteristics of low cost,large reserves,and excellent performance in the field of electrocatalysis,which has a high research value.In this paper,the design of NRR electrocatalyst based on Cobalt elements and its electrocatalytic NRR performance are studied.In this direction,we have done the following three works.1.CoO nanoparticles were simply prepared by the urea process followed by an annealing step in Ar atmosphere as a highly efficient electrocatalytic NRR catalyst.It showed a FE of 5.1% and a NH₃ yield of 15.2 μg· h^–1· mg^–1cat.at – 0.1 V vs RHE,in 0.1 M Na₂SO₄ electrolyte.2.Through the doping of cobalt element,the NRR performance of TiO₂ electrocatalysis was greatly improved.In 0.1 M Na₂SO₄ electrolyte,the Co–TiO₂ perform as an efficient NRR electrolcatalyst with a NH₃ yield of 18.1 μg· h^–1· mg^–1cat.and a FE of 8.6% at – 0.6 V.Compared with undoped TiO₂,it was significantly improved.3.A conductive organic–metal framework CO₃HHTP₂ was designed.As a porous material,it has abundant active sites and good electrical conductivity,which give it excellent electrocatalytic NRR performance.The Co₃HHTP₂ exhibited high NRR activity with a NH3 yield of 22.14 μg· h^–1· mg^–1cat.and a FE of 3.34% at – 0.4 V vs RHE,in 0.5 M LiClO₄ electrolyte.