Density Functional Theory Analysis of Catalytic Nitrogen Reduction on Metal-Free Boron-Doped Graphene Layers

International Journal of Physics | Vol. 7, No. 4, April 2016 | pp. 25–32

DOI: 10.46882/2016/IJP/000072

Research Article

Title: Density Functional Theory Analysis of Catalytic Nitrogen Reduction on Metal-Free Boron-Doped Graphene Layers

Names of Authors: A. L. Silva¹, Y. W. Zhang²

Authors’ Affiliations: ¹Institute of Physics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil; ²Department of Physics, Tsinghua University, Beijing, China

Abstract: Electrochemical reduction of nitrogen (N²) into ammonia under ambient conditions offers a green alternative to the energy-intensive industrial Haber-Bosch process. This investigation uses density functional theory calculations to analyze the catalytic performance and reaction mechanisms of nitrogen reduction on metal-free boron-doped graphene surfaces. We modeled three distinct configurations: single boron substitution, double boron substitution, and boron-doped vacancy sites. Free energy profiles for intermediate steps leading to ammonia (NH3) were computed using the computational hydrogen electrode model across both enzymatic and consecutive pathways. The calculations demonstrate that boron-doped vacancy sites lower the activation barrier for the rate-limiting nitrogenation step (*N² + H⁺ + e⁻ -> *NNH) to 0.52 eV. This value is significantly lower than the 1.45 eV barrier calculated for pristine graphene sheets. The overpotential required to trigger selective ammonia production on boron vacancy sites was estimated at -0.42 V versus the standard hydrogen electrode. Charge density difference mappings show that boron doping induces localized electron deficiency on adjacent carbon atoms. This electronic reconfiguration stabilizes the adsorbed intermediates. These quantum mechanical insights provide theoretical guidelines for developing metal-free, carbon-based catalysts for efficient ambient ammonia synthesis.

Keywords: Nitrogen reduction; density functional theory; boron-doped graphene; electrocatalysis; reaction mechanism; overpotential

Manuscript Timeline: Received: January 04, 2016; Revised: February 17, 2016; Accepted: March 09, 2016; Published: April 07, 2016

Citation: Silva, A. L., & Zhang, Y. W. (2016). Density Functional Theory Analysis of Catalytic Nitrogen Reduction on Metal-Free Boron-Doped Graphene Layers. International Journal of Physics, 7(4), 25–32.

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