Synergistic impact of Ni–Cu hybrid oxides deposited on ordered mesoporous carbon scaffolds as non-noble catalyst for methanol oxidation

Abstract

Non-conventional soft-template method was deployed in synthesizing high surface area, ordered mesoporous carbon (OMC). Ordered mesoporous framework was confirmed from the collective data derived from XRD, N2 sorption and HR-TEM analyses. 15 wt% of variant compositions of Ni:Cu viz., 3:1, 1:1, 1:3 and pristine nickel and copper were deposited onto the OMC by using NaBH4 as a reductant and cetyltrimethylammonium bromide as capping agent. The effect of the reductant in the formation of a particular metal phase was well comprehended from the high angle XRD patterns; the reduction in surface area of the support after metal deposition was taken into account from the N2 sorption analysis. SEM–EDX and HR-TEM–EDX techniques were useful in quantifying the wt% of the deposited metals. The redox properties, charge transfer resistance and stability of all the catalysts toward methanol oxidation were characterized via cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry, respectively. Among all the tested samples, high specific surface area (436 m2 g−1), highest current density (182.07 mA cm−2), least onset potential (0.34 V) and charge transfer resistance (Rct) value of 0.355 Ω with 87.68% retention in current density over 7200 s were achieved when Ni and Cu were mixed in equal weight% to give NiCu hybrid oxides@OMC electrocatalyst.