NiO nanocrystal anchored on pitaya peel-derived carbon laminated mesoporous composites for the electrocatalytic oxidation of ethanol

Abstract

Direct ethanol fuel cell (DEFC) is a kind of energy conversion device with potential application prospect. The development of non-precious metal-based catalysts with high activity and stability is of great necessary for ethanol oxidation reaction (EOR). Here, the laminated composites with hollow structure were synthesized by a simple strategy, which consists of NiO nanocrystals anchored on pitaya peel-derived carbon (PPC). The electrochemical tests show that the optimal electrocatalyst (NiO@PPC-600) exhibits excellent catalytic activity for EOR with the current density (j) of 231.8 mA cm-2 (1.6 V vs. RHE) under alkaline conditions. Furthermore, the j retention rate (83.0%) of NiO@PPC-600 exceeds that (16.4%) of Pt/C in the long-term 12 h EOR test. The superior properties of the NiO@PPC-600 are mainly ascribed to its mesoporous structure that facilitates electrolyte and electron transfer and the PPC substrate that avoids the shedding of NiO nanocrystals, it has moderate lattice defects and graphitization, minimal contact resistance and Tafel slope. The work provides a simple route to prepare a high-efficient electrocatalyst for EOR, and the reuse of biomass pitaya peel (PP) is realized.