First-Principles Insights into Electrochemical Methanol Oxidation on Boron-Doped Nickel Clusters Supported by Graphene under Alkaline Conditions
Zhao-Zhen Lee, Shiuan‐Yau Wu
Abstract
Methanol oxidation is essential for efficient methanol utilization in hydrogen production and direct methanol fuel cells. This study employs density functional theory (DFT) calculations to explore methanol oxidation reactions on graphene-supported Ni 10 and boron-doped Ni 10 B clusters. The Ni 10 -gra model in an acidic environment demonstrates effective methanol capture with an adsorption energy of −0.48 eV and deprotonates from CO* species with an onset potential of 0.14 V, progressing the CH 2 O* to CHO* step. The primary energy barrier is the conversion of CO* to COOH* with an activation onset potential of 0.38 V, while a strong CO 2 adsorption energy of −0.85 eV complicates the product release. Boron doping in Ni 10 B-gra slightly increases the onset potential to 0.51 V for the same potential-determining step but significantly reduces the adsorption energy of CO 2 to 0.35 eV. Under alkaline conditions, the methanol oxidation reaction is examined on preadsorbed OH* models, including 1–4OH*Ni 10 -gra and 1–4OH*Ni 10 B-gra models. The presence of OH* groups increases the chemical potential of COOH* on 1–4OH*Ni 10 -gra, but this effect is moderated on 0–3OH*Ni 10 B-gra. Additionally, boron doping in 1–4OH*Ni 10 B-gra increases the chemical potential of CO*, resulting in an onset potential for methanol oxidation reaction (MOR) ranging from 0.42 to 0.65 V, which is better than the 0.55–1.07 V range observed for 1–4OHNi 10 -gra. Overall, boron doping significantly enhances the catalytic performance of Ni clusters for MOR under alkaline conditions by adjusting the chemical potentials of CO* and COOH*, leading to lower onset potentials and improved electrocatalytic performance.