First-Principles Insights into Electrochemical Methanol Oxidation on Boron-Doped Nickel Clusters Supported by Graphene under Alkaline Conditions

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 Ni10 and boron-doped Ni10B clusters. The Ni10-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 CH2O* 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 CO2 adsorption energy of -0.85 eV complicates the product release. Boron doping in Ni10B-gra slightly increases the onset potential to 0.51 V for the same potential-determining step but significantly reduces the adsorption energy of CO2 to 0.35 eV. Under alkaline conditions, the methanol oxidation reaction is examined on preadsorbed OH* models, including 1-4OH*Ni10-gra and 1-4OH*Ni10B-gra models. The presence of OH* groups increases the chemical potential of COOH* on 1-4OH*Ni10-gra, but this effect is moderated on 0-3OH*Ni10B-gra. Additionally, boron doping in 1-4OH*Ni10B-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 1-4OHNi10-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.