Cobalt nickel boride as electrocatalyst for the oxidation of alcohols in alkaline media

Abstract

A mixed Co and Ni boride precursor was synthesized via chemical reduction and subsequently annealed at 400 or 500 °C with or without prior addition of the monomer benzoxazine. The resulting mixed CoNiB materials were investigated as electrocatalysts for three alcohol oxidation reactions (AOR) in alkaline electrolyte: the oxidation of glycerol (GOR), ethylene glycol (EGOR) and ethanol (EOR). Comparison of the rotating disk electrode (RDE) cyclic voltammograms for the different catalysts revealed that CoNiB annealed at 500 °C without the addition of benzoxazine exhibited the lowest overpotentials in AORs at 10 mA cm–2, promoting GOR at 224 ± 6 mV lower potential compared to OER. When pyrolysis was conducted at 400 0 °C, the benzoxazine-containing catalyst showed a significant increase in the electrocatalytic activity for the AORs compared to the CoNiB catalyst only. The product selectivity on the different catalysts was investigated in a batch-type reactor with flow recirculation revealing formate as the main oxidation product during GOR and EGOR with faradaic efficiencies (FE) in a range of 60 – 80 %, while acetate was obtained during EOR (FE ~ 85 – 90 %). The electrode potential, electrolyte composition and the type of ionomer were explored with respect to their influence on the GOR selectivity. The use of different ionomers resulted in significant differences in the activity trends between RDE and the batch-type reactor with flow recirculation measurements, indicating a strong influence of the two different substrates used, namely glassy carbon and carbon paper on the catalyst formation and thus on the recorded electrochemical activity.

From Small‐Area Observations to Insight: Surface‐Feature‐Extrapolation of Anodes for Alkaline Oxygen Evolution Reaction

“…[4] Many researchers are currently investigating suitable catalyst materials, [5] and their intrinsic properties such as activity and stability during the oxygen evolution reaction (OER). [6] However, these intrinsic properties do not stand independently, but are superimposed on extrinsic properties such as morphology, adhesion, cohesion, and transport capabilities. [7] The interrelation between these properties poses an ongoing challenge, and AWE anodes have not yet reached their potential operational thresholds.…”

“…The application of AWE allows the inclusion of non‐precious metals as electrocatalysts, thus creating a broader scope for the discovery of new catalysts [4] . Many researchers are currently investigating suitable catalyst materials, [5] and their intrinsic properties such as activity and stability during the oxygen evolution reaction (OER) [6] . However, these intrinsic properties do not stand independently, but are superimposed on extrinsic properties such as morphology, adhesion, cohesion, and transport capabilities [7] .…”

Stable Operation of Paired CO2 Reduction/Glycerol Oxidation at High Current Density

“…The pool of applicable AOR catalysts can be divided into two groups, with both having their own advantages and disadvantages. The first is the nonnoble metal catalysts based on, for example, Co, Ni, − etc. The common feature of these materials is that the onset potential of the AOR is above the oxidation potential of the catalyst surface (≈+1.10 V RHE ); hence, AOR is most likely driven by radicals, just as in the case of the OER.…”

Square-wave pulse electrodeposition of gold nanoparticles for ethanol electrooxidation

“…1 Several non-precious metals, including Sn, Bi, and Ni, have been investigated for their performance in ethanol electrooxidation. However, to address their limited catalytic properties and stability, these metals need to be combined with other metals, such as PtSn, 2 PtSnRh, 3 PtBi, 4 RhBi, 5 PdPtNi, 6 CoNiB, 7 CoNi, 8 to improve their low catalytic properties and stability. Previous studies identified Platinum 9–11 and Palladium 12 as the efficient electrocatalysts for low-temperature DEFC applications.…”