Strain boosts CO oxidation on Ni single-atom-catalyst supported by defective graphene

In order to realize the sulfur and water resistance and facilitate the CO oxidation reactions,the effects of strain on the adsorption of CO,O_(2),SO_(2)and H_(2)O molecules on Ni single-atom-catalyst supported by single-carbon-vacancy graphene(Ni-SG) have been studied based on first principles calculations.It shows that the compressive strain increases the adsorption energies of all above mentioned molecules on Ni-SG,where SO_(2)is adsorbed more strongly on Ni-SG than CO.However,in the presence of tensile strain,the adsorption energies decreases significantly when the molecules(O_(2)and SO_(2)) obtain electrons from NiSG,while the adsorption energies just slightly decrease when the molecules(CO and H_(2)O) lose electrons to Ni-SG,which finally achieves the preferential adsorption of CO and O_(2)molecules on Ni-SG by tensile strain.In addition,with tensile strain increasing to 10%,the rate-limited energy barrier along Eley-Rideal(ER) path monotonically increases from 0.77 eV to 0.98 eV,while the rate-limited energy barrier along Langmuir-Hinshelwood(LH) path monotonically decreases from 0.54 eV to 0.44 eV,indicating that the tensile strain can facilitate the LH mechanism while imped the ER mechanism on Ni-SG.The Hirshfeld charge and orbital levels of O_(2)and CO molecules are modulated by the tensile strain,which plays an important role for the decreasing of energy barriers for CO oxidation.Overall,the tensile strain can enhance the sulfur and water resistance of Ni-SG,as well as boost the CO oxidation reactions.

Overview of emerging catalytic materials for electrochemical green ammonia synthesis and process

The concept of“green-ammonia-zero-carbon emission”is an emerging research topic in the global community and many countries driving toward decarbonizing a diversity of applications dependent on fossil fuels.In light of this,electrochemical nitrogen reduction reaction(ENRR)received great attention at ambient conditions.The low efficiency(%)and ammonia(NH_(3))production rates are two major challenges in making a sustainable future.Besides,hydrogen evolution reaction is another crucial factor for realizing this NH_(3)synthesis to meet the large-scale commercial demand.Herein,the(i)importance of NH_(3)as an energy carrier for the next future,(ii)discussion with ENRR theory and the fundamental mechanism,(iii)device configuration and types of electrolytic systems for NH_(3)synthesis including key metrics,(iv)then moving into rising electrocatalysts for ENRR such as single-atom catalysts(SACs),MXenes,and metal–organic frameworks that were scientifically summarized,and(v)finally,the current technical contests and future perceptions are discussed.Hence,this review aims to give insightful direction and a fresh motivation toward ENRR and the development of advanced electrocatalysts in terms of cost,efficiency,and technologically large scale for the synthesis of green NH_(3).