Density functional theory calculations were carried out to study the thermal cracking for chrysene molecule to estimate the bond energies for breaking C 10b-C 11, C 11-H 11 and C4a-C 12a bonds as well as the activatio...Density functional theory calculations were carried out to study the thermal cracking for chrysene molecule to estimate the bond energies for breaking C 10b-C 11, C 11-H 11 and C4a-C 12a bonds as well as the activation energies. It was found that for C 10b-C 11 C11-HI 1 and C4a-C12a reactions, it is often possible to identify one pathway for bond breakage through the singlet or triplet states. Thus, the C 11-H11 and C11-C10b bonds ruptured in triplet state whilst the C12a-C4a in singlet state. Also, it was fond that the activation energy value for C4a-C12a bond breakage is lower than required for C10b-C11 and C11-H11 bonds that enquired the C4a-C12a bond ＂bridge bond＂ is a weaker and ruptured firstly in thermal cracking process. It seems that the characteristic planarity for polyaromatic hydrocarbons is an important factor to acquire the molecule structure the required stability along the reaction paths as well as the full octet rule and Clar＇s n-sextet structure, especially when chrysene molecular lose the property of planarity. The atomic charges supported the observation that the breaking bonds C10b-C11, CI1-H11 and C4a-C12a in triplet or singlet states. The configurations in transition state and the conformation for the end products reaction were explained and discussed.展开更多
The hydrogen evolution reaction(HER)as a fundamental process in electrocatalysis plays a significant role in clean energy technologies.For an energy-efficient HER,it demands an effective,durable,and low-cost catalyst ...The hydrogen evolution reaction(HER)as a fundamental process in electrocatalysis plays a significant role in clean energy technologies.For an energy-efficient HER,it demands an effective,durable,and low-cost catalyst to trigger proton reduction with minimal overpotential and fast kinetics.Here,we successfully fabricate a highly efficient HER catalyst of N-C/Co/Mo_(2)C holey nanorods with Co/b-Mo_(2)C nanoparticles uniformly embedded in nitrogen-doped carbon(N-C/Co/Mo_(2)C)by pyrolyzing the molybdate-coordinated zeolitic imidazolate framework(ZIF-67/MoO_(4)^(2-))holey nanorods,which result from the reaction between CoMoO_(4)and Me IM in a methanol/water/triethylamine mixed solution.The uniform distribution of MoO_(4)^(2-)in the ZIF-67/MoO_(4)^(2-)enables Co/β-Mo_(2)C nanoparticles to be welldistributed within nitrogen-doped carbon holey nanorods.This synthetic strategy endows the N-C/Co/Mo_(2)C catalyst with uniformly decorated bimetal,thus attaining excellent HER electrocatalytic activities with a small overpotential of 142.0 m V at 10 m A cm^(-2)and superior stability in 1.0 mol L^(-1)KOH aqueous solution.展开更多
文摘Density functional theory calculations were carried out to study the thermal cracking for chrysene molecule to estimate the bond energies for breaking C 10b-C 11, C 11-H 11 and C4a-C 12a bonds as well as the activation energies. It was found that for C 10b-C 11 C11-HI 1 and C4a-C12a reactions, it is often possible to identify one pathway for bond breakage through the singlet or triplet states. Thus, the C 11-H11 and C11-C10b bonds ruptured in triplet state whilst the C12a-C4a in singlet state. Also, it was fond that the activation energy value for C4a-C12a bond breakage is lower than required for C10b-C11 and C11-H11 bonds that enquired the C4a-C12a bond ＂bridge bond＂ is a weaker and ruptured firstly in thermal cracking process. It seems that the characteristic planarity for polyaromatic hydrocarbons is an important factor to acquire the molecule structure the required stability along the reaction paths as well as the full octet rule and Clar＇s n-sextet structure, especially when chrysene molecular lose the property of planarity. The atomic charges supported the observation that the breaking bonds C10b-C11, CI1-H11 and C4a-C12a in triplet or singlet states. The configurations in transition state and the conformation for the end products reaction were explained and discussed.
基金National Institute of Advanced Industrial Science and Technology(AIST)the Japan Society for the Promotion of Science(JSPS)for financial support。
文摘The hydrogen evolution reaction(HER)as a fundamental process in electrocatalysis plays a significant role in clean energy technologies.For an energy-efficient HER,it demands an effective,durable,and low-cost catalyst to trigger proton reduction with minimal overpotential and fast kinetics.Here,we successfully fabricate a highly efficient HER catalyst of N-C/Co/Mo_(2)C holey nanorods with Co/b-Mo_(2)C nanoparticles uniformly embedded in nitrogen-doped carbon(N-C/Co/Mo_(2)C)by pyrolyzing the molybdate-coordinated zeolitic imidazolate framework(ZIF-67/MoO_(4)^(2-))holey nanorods,which result from the reaction between CoMoO_(4)and Me IM in a methanol/water/triethylamine mixed solution.The uniform distribution of MoO_(4)^(2-)in the ZIF-67/MoO_(4)^(2-)enables Co/β-Mo_(2)C nanoparticles to be welldistributed within nitrogen-doped carbon holey nanorods.This synthetic strategy endows the N-C/Co/Mo_(2)C catalyst with uniformly decorated bimetal,thus attaining excellent HER electrocatalytic activities with a small overpotential of 142.0 m V at 10 m A cm^(-2)and superior stability in 1.0 mol L^(-1)KOH aqueous solution.
