Electroless Ni–B supported on carbon for direct alcohol fuel cell applications

Ni–B coatings were deposited by electroless technique onto the surface of commercial carbon electrodes for direct alcohol fuel cell applications. An acidic bath having nickel chloride as a source of nickel and dimethyleamine borane (DMAB) as a reducing agent was used to prepare the electroless Ni–B coatings. The boron content of the Ni–B/C deposits was determined by inductively coupled plasma-mass spectrometer (ICP-MS) and its value was 5 wt%. The influence of deposition time of the Ni–B coatings on the electrooxidation of methanol and ethanol was studied. The structural and textural properties of Ni–B/C coatings were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The fabricated Ni–B/C electrodes exhibited enhanced electrocatalytic activity towards electrooxidation of methanol and ethanol in 1.0 M NaOH. The Ni–B/C catalyst that was prepared after 60 min displayed a higher electrocatalytic activity compared to the other Ni–B/C prepared electrodes or the electroless Ni–P/C electrode. The stability of Ni–B/C electrodes towards the electrooxidation process improves as the time of Ni–B deposition increases; additionally, it is superior to that of Ni–P/C electrode prepared at the same deposition time. The surface coverage of the redox species, the number of monolayer of Ni–B and the transfer coefficient α has been determined.

Research highlights
► Ni-B coatings were prepared by electroless tecnhique from an acidic plating bath.
► The deposited Ni-B/C coatings of 5 wt.% B were mixed microcrystlline- amporhous in structure.
► They exhibited higher catalytic activity towards the electrochemical oxidation of methanol and ethanol in 1.0 M NaOH solution.
► The promoting effect of the alloying B on the oxidation activity of alcohols includes both the stru ctural effect and electronic effect.