TY - JOUR

T1 - A theoretical evaluation of possible transition metal electro-catalysts for N2 reduction

A1 - Skulason,Egill

A1 - Bligaard,Thomas

A1 - Gudmundsdottir,Sigrıdur

A1 - Studt,Felix

A1 - Rossmeisl,Jan

A1 - Abild-Pedersen,Frank

A1 - Vegge,Tejs

A1 - Jonsson,Hannes

A1 - Nørskov,Jens Kehlet

AU - Skulason,Egill

AU - Bligaard,Thomas

AU - Gudmundsdottir,Sigrıdur

AU - Studt,Felix

AU - Rossmeisl,Jan

AU - Abild-Pedersen,Frank

AU - Vegge,Tejs

AU - Jonsson,Hannes

AU - Nørskov,Jens Kehlet

PB - Royal Society of Chemistry

PY - 2012

Y1 - 2012

N2 - Theoretical studies of the possibility of forming ammonia electrochemically at ambient temperature and pressure are presented. Density functional theory calculations were used in combination with the computational standard hydrogen electrode to calculate the free energy profile for the reduction of N2 admolecules and N adatoms on several close-packed and stepped transition metal surfaces in contact with an acidic electrolyte. Trends in the catalytic activity were calculated for a range of transition metal surfaces and applied potentials under the assumption that the activation energy barrier scales with the free energy difference in each elementary step. The most active surfaces, on top of the volcano diagrams, are Mo, Fe, Rh, and Ru, but hydrogen gas formation will be a competing reaction reducing the faradaic efficiency for ammonia production. Since the early transition metal surfaces such as Sc, Y, Ti, and Zr bind N-adatoms more strongly than H-adatoms, a significant production of ammonia compared with hydrogen gas can be expected on those metal electrodes when a bias of 1 V to 1.5 V vs. SHE is applied. Defect-free surfaces of the early transition metals are catalytically more active than their stepped counterparts.

AB - Theoretical studies of the possibility of forming ammonia electrochemically at ambient temperature and pressure are presented. Density functional theory calculations were used in combination with the computational standard hydrogen electrode to calculate the free energy profile for the reduction of N2 admolecules and N adatoms on several close-packed and stepped transition metal surfaces in contact with an acidic electrolyte. Trends in the catalytic activity were calculated for a range of transition metal surfaces and applied potentials under the assumption that the activation energy barrier scales with the free energy difference in each elementary step. The most active surfaces, on top of the volcano diagrams, are Mo, Fe, Rh, and Ru, but hydrogen gas formation will be a competing reaction reducing the faradaic efficiency for ammonia production. Since the early transition metal surfaces such as Sc, Y, Ti, and Zr bind N-adatoms more strongly than H-adatoms, a significant production of ammonia compared with hydrogen gas can be expected on those metal electrodes when a bias of 1 V to 1.5 V vs. SHE is applied. Defect-free surfaces of the early transition metals are catalytically more active than their stepped counterparts.

U2 - 10.1039/c1cp22271f

DO - 10.1039/c1cp22271f

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 3

VL - 14

SP - 1235

EP - 1245

ER -