Establishing dopant design principles for methanol oxidation on graphene-supported nickel clusters: A comparative DFT study of B, P, S, and Se

Methanol oxidation reaction (MOR) plays an important role in direct methanol fuel cells, methanol-assisted hydrogen production, and the carbon cycle involving CO 2 conversion. Developing efficient and low-cost anode catalysts remains challenging because conventional Pt- and Pd-based catalysts suffer from high cost, limited abundance, and poisoning by carbonaceous intermediates. In this work, spin-polarized density functional theory calculations were performed to investigate MOR on graphene-supported heteroatom-doped nickel clusters, Ni 10 X 3 -gra, where X = B, P, S, and Se. These simplified atomistic models were designed to compare local dopant effects under the same Ni atom number, dopant number, and graphene support environment. Structural screening and outer-Ni deletion analysis further indicate that heteroatom incorporation enhances the relative resistance of the Ni cluster toward outer Ni removal, with B doping showing the strongest stabilization effect. On clean Ni 10 X 3 -gra surfaces, the MOR activity follows the order Ni 10 B 3 -gra > Ni 10 Se 3 -gra > Ni 10 S 3 -gra > Ni 10 P 3 -gra based on the calculated onset potentials. Ni 10 B 3 -gra exhibits the lowest onset potential of 0.39 V because it provides a favorable balance between methanol activation and CO* oxidation. Under hydroxyl‑covered conditions, the activity trend changes to 4OH*-Ni 10 S 3 -gra > 4OH*-Ni 10 P 3 -gra > 4OH*-Ni 10 B 3 -gra > 4OH*-Ni 10 Se 3 -gra. The 4OH*-Ni 10 S 3 -gra model shows the lowest onset potential of 0.58 V and the smallest increase after OH* coverage, indicating superior tolerance toward hydroxylated surface environments. Transition-state calculations for CO* + OH* → COOH* further support the kinetic feasibility of the key CO* oxidation step and show that 4OH*-Ni 10 S 3 -gra maintains a balanced thermodynamic–kinetic behavior. Electronic structure analyses reveal that heteroatom doping and OH* coverage moderately regulate Ni 3d states without electronically deactivating the Ni cluster. Overall, this work establishes environment-dependent dopant design principles for graphene-supported Ni-based MOR electrocatalysts.