Effect of Heat Treatment and Bath Compositions on the Performance of Co-Ni-Mo-P Electrocatalysts for Ethanol Electro-Oxidation

Abstract

As-deposited (ASD) Co-Ni-Mo-P electrocatalyst on carbon support was investigated for the ethanol electro-oxidation. Electrocatalysts were prepared by electroless deposition method on carbon substrate support (CCS) made active for electroless deposition with Pd-ink. The reaction performances for all electrodes were investigated using cyclic voltammetry (CV). An effect of electroless bath compositions was studied. The result showed that the current density tended to increase with increasing Co, Ni, and Mo contents, suggesting that they contributed to the catalytic activity. The optimum molar ratio of NiSO4, CoSO4, and Na2MoO4 was 1:1.8:0.6 for the catalyst without heat treatment. In addition, after the electrocatalysts were treated thermally for 2h under H2/Ar gas at different temperatures, an optimal temperature of 400°C was identified for which the current density was higher than any other annealing temperature including that of the ASD electrocatalyst. The result is attributed to the effect of crystallinity and particle sizes. Above and below this optimal temperature, the current density decreased, indicating that the crystalline structures at these conditions are not appropriate for optimal performance. Moreover, the active surface area decreased after the heat treatment because the catalyst lost its amorphous structure. Additionally, the stability of the ASD and thermally treated electrocatalysts will be discussed. Figure 1