Anchoring CoFe2O4 nanospheres on two-dimensional microporous carbon from walnut shell as efficient multifunctional electrocatalyst

Abstract

High performance electrocatalysts based on CoFe2O4 nanoparticles and biomass derived active carbon were fabricated via sustainable, inexpensive route utilizing waste walnut shell as a naturally occurring carbon precursor containing abundant amount of nitrogen and oxygen. The CoFe2O4 supported on active carbon, as a trifunctional electrocatalyst for the oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction, exhibiting extraordinary electrocatalytic activities in 0.1 ​M KOH solution. The catalyst shows good oxygen reduction reaction activity with positive onset potential of 780 ​mV (vs. RHE), a diffusion current density of −5.40 ​mA ​cm−2. As oxygen evolution reaction catalyst, it exhibits high current density (50 ​mA ​cm−2 at 2.15 ​V) and a small potential of 1.683 ​V ​at 10 ​mA ​cm−2. This catalyst also shows better hydrogen evolution reaction behavior with a small potential (−0.6505 ​V) at −10 ​mA ​cm−2. Moreover, the catalyst shows better stability and methanol tolerance compared to that on the commercial Pt/C, suggesting that the composite can be a new outstanding multifunctional catalyst in catalysis fields.