Journal of Applied Electrochemistry, Vol.47, No.8, 905-915, 2017
Multiwalled carbon nanotubes twined alpha-nickel hydroxide microspheres as high-efficient urea electrooxidation catalysts
Multiwalled carbon nanotube (MWCNT) twined alpha-Ni(OH)(2) microspheres, denoted as alpha-Ni(OH)(2)@-MWCNT, are synthesized by a facile solvothermal method and are developed as a remarkably active catalyst for urea electrooxidation in alkaline media. Through optimizing the mass ratio between alpha-Ni(OH)(2) and MWCNT, it is found that alpha-Ni(OH)(2)@MWCNT catalyst with a weight ratio of 2.5:1 affords the highest current density of 2503 mA cm(-2) mg(-1) at the potential of 0.58 V versus Hg/HgO and the largest exchange current density of 1.49 x 10(-4) mA cm(-2) among all the studied catalysts, which are much higher than that of pure alpha-Ni(OH)(2) microspheres and are about one order of magnitude higher than that of reported Ni(OH)(2) nanosheets. Additionally, the alpha-Ni(OH)(2)@-MWCNT catalysts also present superior durability than pure alpha-Ni(OH)(2). The exceptional catalytic performance of alpha-Ni(OH)(2)@MWCNT catalysts is attributed to the good electronic transport of MWCNT and favorable mass transport facilitated by alpha-Ni(OH)(2) hollow porous microspheres. These results suggest the feasibility of an easy and low-cost solvothermal method to develop high-efficient catalyst for urea electrooxidation.