Insights into reaction pathway induced by d orbital occupancy on cobalt supported boron nitride for N2O catalytic decomposition

Abstract

Nitrous oxide (N2O), as a typical greenhouse gas, is urgent to be eliminated to address the global climate issue. Developing low-temperature N2O decomposition catalysts is crucial for mitigating greenhouse gas emissions. Herein, we propose a Cobalt-supported boron nitride (Co-BN) catalyst with a low reaction energy barrier (1.37 eV) using density functional theory calculations. The coordination environment is critical to the reaction mechanism and energy barrier, where the CoN3 configuration (Co coordinated with three N atoms) triggers the Eley-Rideal (E-R) mechanism, but the CoB3 configuration (Co coordinated with three B atoms) engenders the Langmuir-Hinshelwood (L-H) mechanism. Fundamentally, the reaction mechanism is dominated by d orbital occupancy. Following the adsorption of *O intermediate, a fully filled d orbital is realized on *O-CoN3, which prevents N2O from bonding with Co, thus following the E-R mechanism through directly interacting with *O specie. Conversely, the partially unoccupied d orbital is identified on *O-CoB3, provinding the bonding site on Co for N2O molecule, thereby leading to the L-H mechanism. Our work provides a novel N2O decomposition catalyst theoretically, and the insights into the relationship between d orbital occupancy and the reaction mechanism, would pave a new avenue for the design of N2O decomposition catalysts.