Wenlong Guo

Promoting Effect of Co in NimCon (m + n = 4) Bimetallic Electrocatalysts for Methanol Oxidation Reaction

Ni-based bimetallic alloys have superior physiochemical characteristics compared to monometallic Ni. In this study, a new type of low cost bimetallic NimCon (n + m = 4) electrocatalysts with high active surface were synthesized on Ti substrate through a hydrogen evolution assisted electrodeposition method. The as-prepared NimCon were characterized by XRD, EDS, and SEM. It was revealed that the composition, surface morphology, as well as the crystal phase structure of the bimetallic NimCon electrocatalysts were significantly changed with the increased content of cobalt. Electrochemical measurements showed that the bimetallic NimCon catalysts, compared with the monometallic Ni, have superior catalytic activity and stability toward the methanol electrooxidation reaction. Additionally, Ni2Co2 sample presented the highest oxidation current density and the best durability. The mechanism study based on electrochemical experiments and density functional theory based calculations showed that the doping of Co in NimCon can signally improve the surface coverage of the redox species, weaken the CO adsorption, as well as adjust the CH3OH adsorption. Such understanding is of important directive significance to design efficient nonprecious catalysts.

DFT studies on the interaction of PtxRuyMz (M = Fe, Ni, Cu, Mo, Sn, x + y + z = 4, x ≥ 1, y ≥ 1) alloy clusters with O2

The reaction mechanism of O2 dissociation on PtxRuyMz (M = Fe, Ni, Cu, Mo, Sn, x + y + z = 4, x ≥ 1, y ≥ 1) alloy catalysts have been investigated with density functional theory calculations in this work. For bare alloy clusters, bimetallic clusters are more stable than the ternary alloy clusters. The geometries of the PtxRuyMz–O2 system, O–O bond stretching frequency and electronic-structure details have been investigated. The energies of O2 adsorption on PtRu clusters are slightly higher than those on PtxRuyMz clusters, and the more charge transfer to O2 from the metal cluster, the higher O2 the adsorption energy obtains. The reaction barriers show that the catalytic performance of trimetallic clusters are better than those of bimetallic clusters, and Pt2RuM clusters exhibit superior catalytic activity for O2 dissociation. The different performance of these alloy clusters for O2 dissociation is scrutinised with aid of molecular orbital and natural bond orbital population analysis.